There are a lot of people that knows a lot, but very few that can explain things in the way that anyone can understand, like you do. Thanks a lot for taking the time.
Exactly right. I just randomly came across this video and the teaching was so good I just watched it all the way through to the end. What a great teacher.
@@theradiomechanic9625 I'd like to point something out that a non-electronics person would find magical - at time 21:50, the sheetrock screw is turning red hot. And there is nothing visible to explain this. What this indicates is a capability of all collections of atoms (all objects of matter). This capability is for accelerations of the charged particles inside a matter object - in this case a screw - to reach a very high rate, to the point of glowing red hot. There are two important aspects to this: 1) if you conducted this exact same experiment in space - outside Earth's atmosphere - THE SCREW WOULD STILL GLOW RED HOT. The bright red color does represent heat, but the coldness of space will not stop the atoms in the screw from reacting to the high frequency induction from the copper coil. The electromagnetic (EM) waves - in the visible part of the EM spectrum, ie, in the 'visible light' spectrum - the electrons in the atoms of the screw are accelerating in back-and-forth oscillations in the 'red' color part of the visible light spectrum. 2) We (a small group of people with physics and elec. engr. backgrounds) rely on the Lorentz force, involving a coil conceptually similar to this one, and a strong, static magnetic field, at right angles to the coil, to create COHERENT accelerations of the charged particles in thin metal layers. At the very high frequencies we use (microwave frequency from a klystron tube feeds our coils), the 'skin effect' prevents the accelerated motions of the charged particles from being deep in the material. We use a thin-film deposition sputter to create very thin layers of metals because of the skin effect. So at time 21:50, the red-hot glow from the sheet rock screw represents RANDOM accelerations, back-and-forth motions, of the tiny individual particles that make up the screw. Another way is to use a coil and a static magnetic field positioned at a 90 degree angle to the coil and impose COHERENT accelerations of the particles in a metal. In our case, all the particles are working together to "pull the cart in the same direction" instead of being random. The surprising thing to most (non-technical) people is - the red glow of the screw, with no visible cause. The surprising thing to most technical people is - the difference between an imposing of random motions (coil only), versus coherent motions (very high frequency coil, static magnetic field orthogonal to the coil, leading to Lorentz force-imposed coherent particle motions). Your demo is very thought provoking and is a wonderful way for people to get exposed to the invisible force fields they never think about. Thank you! .
@@theradiomechanic9625 23:00 u can use clamp multimeter - just make sure it doesn't touch anything cuz will melt the plastic probably :D 26:30 it's not 'more efficient' - it heated up faster because coil is smaller, but power is determined by frequency times current - which u have twice more combined... If you lower your coil diameter you will heat it ~twice as fast it doesn't matter how many Watts the device has if it's poorly design
Two of the main reasons we've converged on polypropylene as the dielectric of choice for power electronics are low dissipation factor and low dielectric absorption. You've provided an excellent example of why these matter.
"Hit" and "ring" love that description, you just gave me the missing key to so much understanding of electronics, so many dots were just connected for me... if only you were my physics teacher! Learned more in 30 min, than piles of confusion thrown at me over the years. THANK YOU.
Okay, overall and excellent video, and yes a ZVS is quite simply a high power oscillator circuit, and the demonstration with the old ignition coil is a very good example of resonant ringing, and I have spent a while reading through some of the more than 600 comments, and it would take forever to address all of them, so I'm just going to hit on a couple, one fellow asked if you could place the coil away from the ZVS and feed it with heavy wire, and the answer to that is yes, but it can only be done if you run a twisted pair of wires, and the resonating capacitors have to stay with the coil, the reson for this is as he mentioned the circulating current between the coil and capacitors is quite high actually in some cases several hundred amps, which is why it's hard to find capacitors that will tolerate the abuse, while the current passing through the twisted pair will only be about half of the supply current, the other reason is, if you add any conductor length between the coil and the resonating capacitors, it becomes apart of the restaurant circuit, there by adding to the coils inductance, and lowering the oscillating frequency, and thereby radiating some of the high frequency magnetic field away from the work where it's needed. The reason for the twisted pair is that it lowers the inductance of the two conductors as the current is flowing in opposite directions, which causes the magnetic field to cancel out, and the twisting cancles out the electrostatic radiation, not that the electrostatic radiation is a problem at those low voltages but just good practice, I mean a piece of zipp cord will work if is all you have, or if you have a piece of 2 conductor SO or SJO that is essentially a twisted pair with a jacket. And no orbis that is not the case, if it were UHF radio couldn't exist, this thing is running at 95.5Khz compared to the AC mains it's high frequency, but in the world of RF it's barely high enough to qualify as RF, no the problem is that it falls victim to it's own magnetic field, even the copper tubing gets hot for the same reason, it's own diameter is large enough to cause it to be inductively heated, and the magnetic field is much more intense near the coil, with small diameter objects, like that drywall screw it gets alot hotter alot faster if you move over to the edge of the coil where the field is more intense, therefore if you want the coil to not heat it's self then yes like one fellow said take a bunch of small gauge magnet wire, and it has to be magnet wire, because the strands cannot touch one another electrically, physically yes, it's like laminating an iron core for a transformer, each lamination is dipped in insulating varnish so that they don't make contact with one another otherwise they would act like a shorted turn secondary and would get extremely hot and burn the whole thing up, if you look at the coil in one of these inductive cook tops you will see that it uses a pancake coil that is many strands of paralleled finely stranded copper magnet wire. Now as for the ignition coil it doesn't need to have that capacitor across it to make it ring, remember that secondary winding of many hundreds of turns, that was under the yellow stickey note, there's a fairly large amount of naturally occurring capacitance between the turns, enough to make it ring, the problem is that the field needs to collapse rapidly, well, with out the capacitor there, it cannot do that, the reason it cannot is because as the connection is broken, either through a set of braker points, or by pulling the wire away from the coil terminal is that the field starts to collapse rapidly causing the polarity of the coil to reverse and the voltage to soure to many times the applied voltage which creates a plasma between the contact points and it's this plasma that used to burn up the breaker points in the old school ignition system, but the plasma is conductive, so as the contact points move away from each other and the plasma grows in length it becomes higher in resistance and dissipates more power finely when it breaks there's not enough energy left to produce a ringing, what the capacitor does here is slow down the collapse of the magnetic field enough to allow the contact points to break the circuit without creating the plasma which allows the field to collapse much faster than it would have. However if you use a high voltage power mosfet to act as the braker points it's much faster the field collapse is much faster resulting in a lot higher ringing and a much higher voltage and a much hotter spark, and for anyone reading this, mosfets with a drain to source voltage of at least 400 volts is a must, as the collapsing field voltage can soure into the mid 300's on the primary winding producing 35 to 40 KV on the secondary.
You will need a 48 to 50 volt supply that can supply around 20 amps of current. Turn on the power supply first, then use a second switch to turn on the DC to the induction heater.
Yes, you can/could drive the gate with a timer and not have to worry about the circuit starting. This is basically how commercial units work using an oscillator to drive a high power amplifier. These units are basically toys and have been cut to the bone to keep them cheap and simple. Tradeoffs that require smacking the thing to get it to ring. And yes, wire wound resistors can cause issues in R.F. Circuits or even down into the ultrasonic range. That has caused grief for a lot of newly minted engineers.
The Radio Mechanic, I in a past lifetime did electronics as a trade, I have forgotten more than I learned and am so out of touch with current (pardon the pun) tech as to say I would have to go back to tech to try and catch up. One thing mentioned in this thread does remind me of some resistors I used to have from an older Radar circuit. They were glass encased (for high voltage I think) Bi-Filar wound wire resistors to reduce the inductive influence on the circuit they were used in. I also remember that carbon resistors with the way they gain different values can also have this inductive effect to perhaps a lesser extent in a very high frequency cct. Please correct me if I am wrong in saying that as I think I should do a refresher of sorts and would prefer to have good information than go on believing something that is wrong. Cheers from John, Australia.
Very helpful info. I have a Chinese IDH and have not tried it at higher than 24vdc. Now I will be trying it at 36vdc as they recommend. Your explanation convinced me that it will handle the power and I can get some use out of my heater.
I work on old motorcycle that have points in the ignition system and have never never been told anything close to what you talk about in your side tangent! now it all makes sense!
A little trick we used to use on the old tube amps when you're fighting the 120 HZ frequency out of the power transformer.. you could use a small choke and cross it with a capacitor.. The voltage will rise so you need a high voltage capacitor. It's a one-hit wonder..... You can Target that frequency. It worked very well it killing the 120 hz hum. But because you're targeting just one frequency in building a tank circuit.. Other odd harmonics find their way through.
I'm an EE and learned something from the video. The tip about the need for a fast rising input voltage I wouldn't have considered but it makes total sense. Thanks for explaining that in detail.
Thanks for the video. I've looked at this circuit before and thought that if the transistors come on at the same time, it would just be a dead short from the supply to ground through the transistors. You are the first person I have seen that has mentioned that.
I have not put them in an induction heater yet, but I wound my own capacitor. Started with with an aluminum tube about .25in bore. Wrapped layers of wax paper and aluminum foil from a grocery store, to a diameter that just fits inside a 3/4" copper pipe. I left one layer of foil in contact with the inside tube and one in contact with the copper tube. Slipped the roll in to the coper tube and potted the end with epoxy. The filled with mineral oil being careful not to get any on the potting area for the top end, and potted it. I can then run coolant thru the inside, and the large area also helps keep it cool.
I think that with the high currents involved in these heaters you are better off going point-to-point rather than PCB. And you are better off using a bunch of smaller value caps rather than a few high value caps for resonating your coil. The circulating currents here are probably hundreds of amps. So you want to split this current up, and also a smaller ESR loss resistance means higher tank currents. This gives you more heating power for a given input power.
The advice you give at 8:00 is exactly why the guy of channel "AVE" blew up his induction rig and blamed the chinese. I just received a supposedly 1000W 50A from china (35$ !), can't wait to try it out !! I'm hoping I can get rid of my acetylene torch after that !
I don't understand why they didn't add the needed components to prevent a slow rise from locking it up in the first place, but it does look like they attempted to point it out.
Some Comments:1. Since the switching frequency of the Chinese module is half of yours the switching losses will be half. However, the lower frequencies will only work with steel or ferrous metals. High frequencies > 180Khz will allow the induction heater to work with brass, solder, alum. and perhaps copper.2. Copper wire vs Copper tubing. Your 10 gauge wire will not be able to handle higher current do to the skin effect. All of the current will flow through just the outer skin of the wire. Copper tubing will perform better since it has a larger surface area.3. The biggest problem that cause blown transistors is induction spikes with the transistor turn off. Even if you're putting in low voltage, the tank can create much higher voltage spikes that exceed the transistor voltage limit. This is usually lead to sudden and dramatic transistor failures. At higher input voltage, snubbers must be used to clamp the induction spikes so they don't exceed the transistor's voltage limit.
Hi Guy, thanks for the insight. When time permits I may try winding another coil from tubing and bring the frequency up. I totally understand the circulating currents and voltages involved. However you still need to hit the things with full starting voltage ( or high enough to make the tank circuit ring ) or both transistors will come on together and basically explode. Once it is in oscillation you can bring the voltage down to reduce power with no problems. Haven't blown a single transistor other than the very first attempt where I connected the supply then turned it on.
Before seeing this video I couldn't figure out why my zvs induction heater was blOwing off continuously on transformer power supply now I've figured it out thanks!
Perfect explanation. No heat sink/transfer compound between the switching transistors/Mosfets and heat shields, which seems to be the norm with these and similar products. Made to a price of course. I've had to add it myself. 16min - So glad I'm not the only one who forgets which way to turn the lever for Close Ups or Wide Angle.
nice video... It looks like you know exactly how these things work, I just got one a 900w Im planing on making a low laying fog machine, heat up water and spray it on to dri ice, Im planing on reduce the diameter of the coil to about 1inch and increase the number of turns so I could increas the heating area. keep up the videos... 👍
Really a very thorough explanation. I was looking at these because they are very cheap way of induction melting. Now I have to find a better power supply
At 180 khz, skin effect depth of copper is 153 μm or just 0.153 mm of the skin of your 10 gauge wire coil is actually conducting. I'm peaty sure that is the majority of the cause of the heat in your copper coil. Rough calculations: 10 gauge wire has diameter of about 2.58 mm or a cross section of 5.26 mm sq. If we subtract skindepth 2×.153 mm from the diameter, then you have about 2.28 mm diameter of copper wire providing support but not conducting. That works out to about 4.09 mm sq or 78% of the 10 gauge wire not conducting. You may get far better performance from a litz wire coil with the about the same copper cross section as the 10 gauge wire. While 24 gauge wire still has some skin effect at 180 kz , a much larger percentage of the copper wire is conducting. 25 strands of 24 gauge magnetic wire twisted on each other should almost equal The copper cross section of one strand 10 gauge wire, but will conduct far better. 25 stranded litz wire could be simply made by twisting 5 stands together into one long wire. Cut it in fiths and then twist those 5 twisted wires into one litz wire for your coil.
You'll find solder won't heat readily with these units. They don't switch fast enough. Work around by using a graphite or steel crucible. AvE blew his up by starting up the unit with the load in place. Doing so damps down the inrush before ringing can establish. See the next-to-last item in the seller's list of notes.
You can wind a larger coil if desired without much problem. The main issue is pumping enough power into the unit to make it melt the aluminum. This unit is basically a toy. But if you have a power supply around 50 volts and 30 amps is should just be enough to make it work.
For those using graphite crucibles, be aware: Graphite becomes more and more electrically conductive as temperature increases, which will divert inductive heater energy away from your crucible contents. Using a too-large graphite crucible may be fine at low temperature, but when it gets hot it will "act bigger" and there is where you may blow your heater circuit. My advice is to use conductive crucibles only when necessary, such as with powdered metals or other poor conductors of electric current. Consider using properly-sized non-conductive crucibles with a piece of solid metal or graphite inside as a "local heat source". Choose a material which will not chemically react with the material being heated, unless that is your goal. Here is a page of some experimental audiophile discussing the temperature/resistance effect of graphite in terms of everyday temperature and resistance units. Note graph at bottom of page: www.troelsgravesen.dk/graphite.htm
No wonder mine doesn't work well. Thanks for dedicate your time help others see a very important point. May I ask if I use a switching stick welding (MMA ) typically 54VDC as a power supply, would it damage the chip. Suppose my fans can handle the voltage.
That was an excellent video! I have one of the Chinese induction heaters and you probably just saved me a lot of grief. Thanks for taking the time to post this. Greetings from Arizona.
Thanks for watching, and thanks for the nice note. Actually having fun making these when I get time. And yes, many ways to make a supply. A little imagination is all it takes.
PSA... if you decide to water cool the unit be sure to place the pump after the radiator and before the coil, you want the coolest water to run thru the pump... also, a cap and SCR is a kewl way to "jump start" the system, use a push button to get the gate to trigger the SCR.
Really nice video. I always wonder if these Chinese induction heaters/zero voltage switches are any good. Your diy coil is probably heating up even more through the skin effect: All the current is flowing on outer part of the conductor with that high frequencies :)
Make sure to spread the coils out. If they are touching it lowers the inductance and results in overheating the circuit. Otherwise these little units are really handy to have. Most of what I heat treat is small enough to fit through the coil. You can use a foot switch and only have the unit on when you are actually heating something. Neater, easier and nowhere near as hazardous as a propane torch. It's a good idea to rig an old computer fan and you can rig up an SCR control so you only make as much heat as you really need.
Hi Lawrence, they certainly are handy, and cheap to boot. Aware of the coil issue, but that is good information to pass along to the viewers. Never thought to mention it as it is second nature to me. Thanks for the tip/reminder.
Thumbs UP! Very good tutorial, thanks. I am looking at buying an 1800 Watt one of these and having read the ebay add was confused about the supply voltage rise time. I would have cooked the thing first go had I not seen this video. I like yourself have and want to use a Variac to control the output/heat so again this was the perfect video for my education. Thanks again, cheers from John, Australia. PS Just Subscribed.
His home-brew version is similar to early inverters, which used simple SCRs as the power switching elements. The oscilloscope views showing the DC-separated AC half-cycles give a clue to how SCRs were made to turn off... zero current flow does it.
I have a chinese induction heater, but I do not have a power source. What I do have, is 3 car batteries which I can put them in series and get 36v, will it be ok?
Nice demonstration, What is your suggestion, if I use this circuit to build a cooktop which can run over 24v through solar panels.... My idea is to get solar power directly and utilize it for cooking purpose...
Here in the U.S. we have a home improvement stores ( Home Depot and Lowes ) both sell them. Just do a search for counter top inductive cook stove. There are many.
I enjoyed the video as it delved in depth very clearly without unduly going to town on the actual circuit function.......nice to know that if you "invest".....it's a fun thing, innit?........ in one of these devices from China you'll get your money's worth as it will work as instructed. Based on this video I'll try and source the higher power one...... I might as well now it's known that it can do some magic smoke raising......more power iz guut, ja? I just can't be bothered to try and make one when you can get one that will work out of the box.
What you are saying, BUT an automotive coil fires as the magnetic field collapses when the points are open. The capacitor is across the breaker points, not the coil unless you are trying to say it's a series tank circuit, but that isn't what you are saying. The 12 Volts is attached to one side of the coil primary the other side goes to through the breaker points to ground. The primary of the coil is "charged" when the points are closed, building a magnetic field around the core and saturating it. When the points open that field collapses inducing a high voltage into the secondary of the coil, also, a lot of coils are one coil with the primary nothing more than a tap places close to one end of the coil. Your parallel tank circuit needs to be very close to resonance at your oscillators frequency. For it to ring at a given frequency it has to be tuned to that frequency. For it to ring the cap has to charge then it discharges into the inductor, then back and fourth. That's what the ringing is. To maintain the ringing the energy loss must be replaced by a "kick" or a oscillator at the proper frequency.
Thanks, a nice video. Why are the transistors not interlocked so they cannot turn on together? I've spent many years working on commercial inverters (usually H drive config) and no matter what happens at the battery end they will not get locked up. However one drop of condensation on the PCB.......
regarding the ignition coil the spark occurs when you interrupt the current and dissipates the energy stored in the magnetic field of the primary coil. the capacitor is there to tune the primary to the frequency the secondary has with its stray capacity so effectively turning the ignition coil into a resonant transformer (tesla coil)
when switch ON is fast enough, asymetries in the two legs cause the LC circuit ringing and thus start the oscillator, while switching OFF causes the ign coil with its capacitor ringing until the stored energy is used up by the spark which effectively short circuits the secondary and stops ringing but okay lets leave it at that
Would like to make an induction sewer cooker, with cast iron pipe. Septic is expensive, but human waste can be made safe if heat treated. Solar/wind plus induction seems to be a good choice, as one often needs an energy dump. Would be much better for the environment. Septic systems can cost between $5000 to 10,000 dollars. Would seem you could burn poop for far less, and make it safe for fertilizer .
I believe that is what some of the city sewer plants do. They filter, burn/cook/heat then spread it on newly seeded construction sites. Grass grows like crazy.
If you want to see a decent induction furnace visit an aluminium smelter, we have had one here in the state located at Bell Bay, Georgetown, Tasmania, since the sixties, originally Comalco aluminium, you need your own power station to run it. excellent video and commentary thanks..
You probably do need your own power station or a very good deal with a local one to run a primary smelter, but for remelt the power needs are much, much lower.
Lets face it. These are basically toys that get used a couple of times, blown up and that is the end. The real issues these days are all the crappy switching wall warts, crappy led lights and all the other cheap consumer junk from China that runs every day most of the day. That is where the R.F. Noise Floor is coming from.
Question: Do you think it would be possible to run the induction heater by using a Peltier - (TEG) generator? (using a stove as heat source... Just curious...
Hi RM, Would this Chinese inductor be suitable for use on 13mm exhaust bolts? I would also like to use the wire type coils as used with "bolt buster" and the likes due to the location of the bolts, is that possible? I see that when use the inductor you don't use cooling, is cooling necessary? If cooling is needed can you point me in the right direction? As I would be using the device as a "mobile device" is it possible to fit a case for handling? If so can you recommend a case? Would the smaller unit be adequate for the job I'm doing? Finally can you recommend a cheap power supply? Thanks in advance, Mark
Would attaching a switch to my 12VDC supply battery be sufficient to have a fast rise time pulse, or would the minuscule bouncing of the switch being put in the on position wreck the circuit too?
The best chinesium money can buy! I am interested in building a brass annealer out of one of these in the future. You should do a video with your explanation of how an automotive coil works for some of the younger folks that don't understand exactly how it works. understanding an automotive oscilloscope and what the patterns mean is becoming a lost art. Just to make sure my understanding is correct, the power supply itself will have to slow of a rise time if your switching on the primary side. So the ideal is to power it constant, and have any switching on and off of the inductive heater circuit should be on the secondary side of the power supply correct?
Oh nice I just left Manch a lil over a year ago, coulda had some great project fun you may have seen me in the local clubs (if ever in any) working on the pool tables for the haunts! Anyway great vid!!
Thanks for sharing. Very informative/educational and very good setup. You are absolutely right about capacitors. Inspiring me to go out and try again! Kind Regards. Pablo
I want to buy or build something like this to heat 1/2" x 1/2" square stock so it can be bent in a hand scroll bender. I have several high wattage 24 volt omron industrial power supplies, do you think 24 volt supplies and this Chinese induction heater would be powerful enough to heat a 2-3" of 1/2" square bar. Thanks
If you don’t mind can I ask a question? If I wanted to temper some steel and the curie affect starts while it’s only cherry red how do you get up to those sort of white hot temperatures needed before quenching it?
The sharp inrush is needed to start the coil "ringing" otherwise both transistors turn on at the same time and blow up. The capacitor ( if after the switch or relay ) will delay the voltage rise causing the same issue. Putting the cap before the switch will also cause a slower rise in voltage as the cap charges. The whole trick is to have full voltage at the switch closure.
I just bought a Chinese inductive heater. It did not come with a coil so I decided to watch a few videos before powering up. This is the first video and i must say its a good thing. I was intending to power with a computer power supply and I have a tendency to just use the switch on the device. It definitely takes some time to come on full when switched on. I never considered this would have been a problem. So that comes to my two questions. 1) if I power on the computer power supply and let it come up properly then use a switch in between that and the inductive loop will I get fast enough switch on? 2) Since no loop was provided or any info on the size what inductance is good. Seems everyone does a few loops but the variation seems be large (2 or 3 loops to about 8). Btw this is the first channel I subscribed to after watching one video. Normally I watch a few before making that decision but this video was so clear and properly explained that I was convinced you have good content.
Hi Manic, Yes, you can turn on the supply then use a switch to turn on the unit and you should be fine. Be advised however the switch needs to be rated for a lot of current. The problem with DC is the arc does not quench when the switch opens unless the switch contacts have a lot of open clearance. As for the coil, ( I am on the road right now and cannot measure the coil ) this is not real critical. Note how many turns mine has and make the coil about 3 inches in diameter and you should be fine. I strongly suggest you make it out of copper tubing at least 1/4 inch diameter ( 6mm ) to handle the current.
THANKS FOR THE GREAT VIDEO!!!! I am somewhat new with ZVS. I have the ebay ZVS board. I need a "final" output of about 600VAC peak at 10A max to connect to a fullwave bridge made of four SiC diodes. What do you suggest I use at the ZVS output...perhaps a type of HF high current transformer??
If you add a secondary winding to your output consisting of a big step up coil you'd have a Tesla coil! I've never seen a water cooled Tesla coil though.
Lot of folks have done that. The reason the tube is water cooled is that the coil is passing very high circulating currents. This causes a LOT of heating in the coil. Tesla coils pass along a lot of that energy into the secondary.
Your spark plug analogy needs a little clarification. The capacitor in an ignition system isn't what causes a resonance, the reverse EMF from collapse of secondary windings induces a 120v to 320v pulse in primary coil. ( you need a PVA for meter to measure it) When ignition is triggered on next rotation, you get a better spark with 'longer' duration
In a simple coil/points ignition the capacitor does indeed produce a resonant circuit prolonging the spark. Trust me on this. Try it yourself. This has been known for 75+ years.
And yes, there is inductive EMF. This is what charges the cap and prolongs the "ring" for the hot spark. The scope pretty much proved it. Resonant inductive/capacitance circuits have been around forever.
Hi, I may be a bit late to the party, but what do you think about microwave capacitors? They should be suitable, aren't they? Also, I thought about getting an old induction cooker and scrapping it for parts. Since its the same technology I think it should work. Basically I just need to wind a new coil and get around the cooking exclusive safety mechanisms. Or am I dunning krügering it and its more difficult?
More than 10 minutes repeating why the Chinese induction heater needs a fast rising power supply voltage. The demonstration of the arc in the spark plug is clear, as the scope display. The 'tank" oscillator produce many arcs which explain the large bright arc instead of the wimpy purple arc. About the transistor explosion: The hypothesis is that both transistor will conduct at the same time, short circuiting each other. Another possible explanation is internal hot spot in the transistor that can happen if the gate voltage is too low to force the transistor into saturation.
Do we actually need both transistors? Can't we just oscillate the tank circuit with something equivalent to a not gate. Similar to a pierce oscillator, but using the tank circuit instead of a crystal?
Thanks for this informative video (I'll definitely be checking out more of your vids!)! I was waiting the whole time (since you are also clearly a fan of analogies) for a "ringing the bell with the fast rise-time of a hammer hit" analogy, and that attempting to do a soft-start was like hitting the bell with a soft object, this just wouldn't have the high frequency component to excite at the resonant frequency of the tank! (Spoken as a radio amateur also of course!) ...great explanation (if not one of the best I've heard, and another great analogy!) and use of the automotive ignition system, also! 73 KA1-RBP
Thanks for watching and the nice words. A nice counter to the comments from "Daite Dve" who said to me quote "Dude you are Soooo Boring." Cant win them all. :-)
Hi Radio Mechanic, why doesn't the work piece move under application of the magnetic field ? I would be worried that the work piece (or the induction heater) would have a rapid and strong movement to maximise flux linkage - parts could topple over, vibrate, spill etc. due to movement.
Excellent question, and the answer is - it does! If you look at the video about soldering PL-259 connectors, and even with the video about the solder pot you will see the solder jump up when the relay turns on the DC power (after it is molten). Small pieces of aluminum in a crucible will "stand up" when the power is applied also. They try to align with the magnetic flux down the center of the coil. The force is not extremely strong, but is present. There is a video on you tube ( forget the title ) where the first three turns of a large induction coil have been reversed. In the video the work piece "levitates" in the field until the part becomes molten and looses magnetic properties, then falls through the coil.
My question would be how can I modify it to make it handle more power. Better transistors, any suggestions? More caps in parallel ? Can you put two transistors in parallel, say two on each side? I just picked mine up from china and it works a treat. But I want more. My psu goes up to 56 volts @ 12a, but I've got it set at 48 for now.Also what affect would having the coil on the end of a long 1m cable have? I'm making mine into a handheld unit to heat up rusted nuts on cars for easier removal.Also what design of coil is the best? One with more turns of thinner guage wire, or just a few thick coils.
Hi Thomas, the parts would have cost me what the unit cost me delivered. And if it dies I can modify it pretty simply. Was mostly purchased as a toy. Thanks for watching.
Thank you very very much for sharing your knowledge and pointing out the point no. 9 which I did NOT understand before watching your video. Question. Do I also need a capasitor after poer suply and before second swith/relay/timer? If yes, what capacity is needed for about 48-50 output volt from power supply? Regards
Radio Mechanic, Yep seen many Chinese crkts costing less than the parts here in the US. Just goes to show how much profit the distributors are making. You know they are getting their components from China as well. Thx for sharing videos take a lot of time. Now as to the heating in your coil vs the Chinese unit. It is simply due to the skin effect. The current is only a one skin depth and their tubing has a larger circumference than yours by what say twice? Just a swag. This means the current density is lower in theirs vs yours. Next is more of the screw is covered by the taller coil, theirs, so more of the screw will get heated and the current drop due to the Currie effect will be larger. Thx again for sharing. As for the fast risetime start up, try what the CFL guys do, they use a Diac to generate the impulse needed to get their crkt working. You would have to create a mod that keeps the crkt from operating until it gets pulsed. Looks like it could be a great solution to the tricky start up problem. Paul
HI, the skin effect is seriously present on both coils. The circulating currents are also quite high. The coil made from tube, while a little slower to heat, heats quickly to the point of blistering and will turn brown/black within a couple of minutes. The reason it is staying cool is the water circulating through it. Without the water the run time is very short. The wire was around 3/16 ( .187" ) diameter and the tube is slightly larger at .200" diameter ( less than 9/32 or .218" ). The wire has more mass to absorb the heat so the temperature rise is fairly close as the thin wall tube does not have the heat capacity. But yes, skin effect is certainly in play here. Sadly we are dependent on cheap Chinese stuff in this country. Would pay a little more for U.S. goods if they were still made here. Sad state of affairs. Thanks for watching and the great comment.
I want to melt and make bars out of scrap silver and silver plate, so will the Chinese model melt silver..? I also have another question could you not recoil the copper pipe into a bigger opening maybe even use say 3 units together so a new copper coil wrapped up into three units into one....?
There are a lot of people that knows a lot, but very few that can explain things in the way that anyone can understand, like you do. Thanks a lot for taking the time.
Bora, thanks for the nice comment. Makes it worth the work.
Typical winter
Exactly right. I just randomly came across this video and the teaching was so good I just watched it all the way through to the end. What a great teacher.
@@theradiomechanic9625 I'd like to point something out that a non-electronics person would find magical - at time 21:50, the sheetrock screw is turning red hot. And there is nothing visible to explain this.
What this indicates is a capability of all collections of atoms (all objects of matter). This capability is for accelerations of the charged particles inside a matter object - in this case a screw - to reach a very high rate, to the point of glowing red hot.
There are two important aspects to this:
1) if you conducted this exact same experiment in space - outside Earth's atmosphere - THE SCREW WOULD STILL GLOW RED HOT. The bright red color does represent heat, but the coldness of space will not stop the atoms in the screw from reacting to the high frequency induction from the copper coil. The electromagnetic (EM) waves - in the visible part of the EM spectrum, ie, in the 'visible light' spectrum - the electrons in the atoms of the screw are accelerating in back-and-forth oscillations in the 'red' color part of the visible light spectrum.
2) We (a small group of people with physics and elec. engr. backgrounds) rely on the Lorentz force, involving a coil conceptually similar to this one, and a strong, static magnetic field, at right angles to the coil, to create COHERENT accelerations of the charged particles in thin metal layers. At the very high frequencies we use (microwave frequency from a klystron tube feeds our coils), the 'skin effect' prevents the accelerated motions of the charged particles from being deep in the material. We use a thin-film deposition sputter to create very thin layers of metals because of the skin effect.
So at time 21:50, the red-hot glow from the sheet rock screw represents RANDOM accelerations, back-and-forth motions, of the tiny individual particles that make up the screw. Another way is to use a coil and a static magnetic field positioned at a 90 degree angle to the coil and impose COHERENT accelerations of the particles in a metal. In our case, all the particles are working together to "pull the cart in the same direction" instead of being random.
The surprising thing to most (non-technical) people is - the red glow of the screw, with no visible cause.
The surprising thing to most technical people is - the difference between an imposing of random motions (coil only), versus coherent motions (very high frequency coil, static magnetic field orthogonal to the coil, leading to Lorentz force-imposed coherent particle motions).
Your demo is very thought provoking and is a wonderful way for people to get exposed to the invisible force fields they never think about. Thank you!
.
@@theradiomechanic9625
23:00 u can use clamp multimeter - just make sure it doesn't touch anything cuz will melt the plastic probably :D
26:30 it's not 'more efficient' - it heated up faster because coil is smaller, but power is determined by frequency times current - which u have twice more combined...
If you lower your coil diameter you will heat it ~twice as fast
it doesn't matter how many Watts the device has if it's poorly design
Two of the main reasons we've converged on polypropylene as the dielectric of choice for power electronics are low dissipation factor and low dielectric absorption. You've provided an excellent example of why these matter.
"Hit" and "ring" love that description, you just gave me the missing key to so much understanding of electronics, so many dots were just connected for me... if only you were my physics teacher! Learned more in 30 min, than piles of confusion thrown at me over the years. THANK YOU.
Your welcome, and thank YOU for watching.
Okay, overall and excellent video, and yes a ZVS is quite simply a high power oscillator circuit, and the demonstration with the old ignition coil is a very good example of resonant ringing, and I have spent a while reading through some of the more than 600 comments, and it would take forever to address all of them, so I'm just going to hit on a couple, one fellow asked if you could place the coil away from the ZVS and feed it with heavy wire, and the answer to that is yes, but it can only be done if you run a twisted pair of wires, and the resonating capacitors have to stay with the coil, the reson for this is as he mentioned the circulating current between the coil and capacitors is quite high actually in some cases several hundred amps, which is why it's hard to find capacitors that will tolerate the abuse, while the current passing through the twisted pair will only be about half of the supply current, the other reason is, if you add any conductor length between the coil and the resonating capacitors, it becomes apart of the restaurant circuit, there by adding to the coils inductance, and lowering the oscillating frequency, and thereby radiating some of the high frequency magnetic field away from the work where it's needed. The reason for the twisted pair is that it lowers the inductance of the two conductors as the current is flowing in opposite directions, which causes the magnetic field to cancel out, and the twisting cancles out the electrostatic radiation, not that the electrostatic radiation is a problem at those low voltages but just good practice, I mean a piece of zipp cord will work if is all you have, or if you have a piece of 2 conductor SO or SJO that is essentially a twisted pair with a jacket. And no orbis that is not the case, if it were UHF radio couldn't exist, this thing is running at 95.5Khz compared to the AC mains it's high frequency, but in the world of RF it's barely high enough to qualify as RF, no the problem is that it falls victim to it's own magnetic field, even the copper tubing gets hot for the same reason, it's own diameter is large enough to cause it to be inductively heated, and the magnetic field is much more intense near the coil, with small diameter objects, like that drywall screw it gets alot hotter alot faster if you move over to the edge of the coil where the field is more intense, therefore if you want the coil to not heat it's self then yes like one fellow said take a bunch of small gauge magnet wire, and it has to be magnet wire, because the strands cannot touch one another electrically, physically yes, it's like laminating an iron core for a transformer, each lamination is dipped in insulating varnish so that they don't make contact with one another otherwise they would act like a shorted turn secondary and would get extremely hot and burn the whole thing up, if you look at the coil in one of these inductive cook tops you will see that it uses a pancake coil that is many strands of paralleled finely stranded copper magnet wire. Now as for the ignition coil it doesn't need to have that capacitor across it to make it ring, remember that secondary winding of many hundreds of turns, that was under the yellow stickey note, there's a fairly large amount of naturally occurring capacitance between the turns, enough to make it ring, the problem is that the field needs to collapse rapidly, well, with out the capacitor there, it cannot do that, the reason it cannot is because as the connection is broken, either through a set of braker points, or by pulling the wire away from the coil terminal is that the field starts to collapse rapidly causing the polarity of the coil to reverse and the voltage to soure to many times the applied voltage which creates a plasma between the contact points and it's this plasma that used to burn up the breaker points in the old school ignition system, but the plasma is conductive, so as the contact points move away from each other and the plasma grows in length it becomes higher in resistance and dissipates more power finely when it breaks there's not enough energy left to produce a ringing, what the capacitor does here is slow down the collapse of the magnetic field enough to allow the contact points to break the circuit without creating the plasma which allows the field to collapse much faster than it would have. However if you use a high voltage power mosfet to act as the braker points it's much faster the field collapse is much faster resulting in a lot higher ringing and a much higher voltage and a much hotter spark, and for anyone reading this, mosfets with a drain to source voltage of at least 400 volts is a must, as the collapsing field voltage can soure into the mid 300's on the primary winding producing 35 to 40 KV on the secondary.
You will need a 48 to 50 volt supply that can supply around 20 amps of current.
Turn on the power supply first, then use a second switch to turn on the DC to the induction heater.
Yes, you can/could drive the gate with a timer and not have to worry about the circuit starting. This is basically how commercial units work using an oscillator to drive a high power amplifier. These units are basically toys and have been cut to the bone to keep them cheap and simple. Tradeoffs that require smacking the thing to get it to ring. And yes, wire wound resistors can cause issues in R.F. Circuits or even down into the ultrasonic range. That has caused grief for a lot of newly minted engineers.
I have one
The Radio Mechanic
Hey will a 48v 10amp power supply work also? Awesome video, best one I've seen regarding these induction heaters
The Radio Mechanic, I in a past lifetime did electronics as a trade, I have forgotten more than I learned and am so out of touch with current (pardon the pun) tech as to say I would have to go back to tech to try and catch up.
One thing mentioned in this thread does remind me of some resistors I used to have from an older Radar circuit. They were glass encased (for high voltage I think) Bi-Filar wound wire resistors to reduce the inductive influence on the circuit they were used in. I also remember that carbon resistors with the way they gain different values can also have this inductive effect to perhaps a lesser extent in a very high frequency cct.
Please correct me if I am wrong in saying that as I think I should do a refresher of sorts and would prefer to have good information than go on believing something that is wrong.
Cheers from John, Australia.
Very helpful info. I have a Chinese IDH and have not tried it at higher than 24vdc. Now I will be trying it at 36vdc as they recommend. Your explanation convinced me that it will handle the power and I can get some use out of my heater.
I work on old motorcycle that have points in the ignition system and have never never been told anything close to what you talk about in your side tangent!
now it all makes sense!
A little trick we used to use on the old tube amps when you're fighting the 120 HZ frequency out of the power transformer.. you could use a small choke and cross it with a capacitor..
The voltage will rise so you need a high voltage capacitor. It's a one-hit wonder..... You can Target that frequency.
It worked very well it killing the 120 hz hum. But because you're targeting just one frequency in building a tank circuit.. Other odd harmonics find their way through.
I'm an EE and learned something from the video. The tip about the need for a fast rising input voltage I wouldn't have considered but it makes total sense. Thanks for explaining that in detail.
Thanks for the video. I've looked at this circuit before and thought that if the transistors come on at the same time, it would just be a dead short from the supply to ground through the transistors. You are the first person I have seen that has mentioned that.
I have not put them in an induction heater yet, but I wound my own capacitor. Started with with an aluminum tube about .25in bore. Wrapped layers of wax paper and aluminum foil from a grocery store, to a diameter that just fits inside a 3/4" copper pipe. I left one layer of foil in contact with the inside tube and one in contact with the copper tube. Slipped the roll in to the coper tube and potted the end with epoxy. The filled with mineral oil being careful not to get any on the potting area for the top end, and potted it.
I can then run coolant thru the inside, and the large area also helps keep it cool.
I think that with the high currents involved in these heaters you are better off going point-to-point rather than PCB.
And you are better off using a bunch of smaller value caps rather than a few high value caps for resonating your coil. The circulating currents here are probably hundreds of amps. So you want to split this current up, and also a smaller ESR loss resistance means higher tank currents. This gives you more heating power for a given input power.
The advice you give at 8:00 is exactly why the guy of channel "AVE" blew up his induction rig and blamed the chinese.
I just received a supposedly 1000W 50A from china (35$ !), can't wait to try it out !! I'm hoping I can get rid of my acetylene torch after that !
I don't understand why they didn't add the needed components to prevent a slow rise from locking it up in the first place, but it does look like they attempted to point it out.
you cannot control a self driven oscillator like that. soft start is only available with a controlled oscillator.
+Richard Smith yeah, i bet i can put an optocoupler into the gd and the input to a capacitor.
Some Comments:1. Since the switching frequency of the Chinese module is half of yours the switching losses will be half. However, the lower frequencies will only work with steel or ferrous metals. High frequencies > 180Khz will allow the induction heater to work with brass, solder, alum. and perhaps copper.2. Copper wire vs Copper tubing. Your 10 gauge wire will not be able to handle higher current do to the skin effect. All of the current will flow through just the outer skin of the wire. Copper tubing will perform better since it has a larger surface area.3. The biggest problem that cause blown transistors is induction spikes with the transistor turn off. Even if you're putting in low voltage, the tank can create much higher voltage spikes that exceed the transistor voltage limit. This is usually lead to sudden and dramatic transistor failures. At higher input voltage, snubbers must be used to clamp the induction spikes so they don't exceed the transistor's voltage limit.
Hi Guy, thanks for the insight. When time permits I may try winding another coil from tubing and bring the frequency up. I totally understand the circulating currents and voltages involved.
However you still need to hit the things with full starting voltage ( or high enough to make the tank circuit ring ) or both transistors will come on together and basically explode. Once it is in oscillation you can bring the voltage down to reduce power with no problems. Haven't blown a single transistor other than the very first attempt where I connected the supply then turned it on.
Before seeing this video I couldn't figure out why my zvs induction heater was blOwing off continuously on transformer power supply now I've figured it out thanks!
Your welcome, and thanks for watching.
Well, It never crossed my mind that that's what the cap in an ignition circuit was actually for. Makes sense now, thanks!
Perfect explanation.
No heat sink/transfer compound between the switching transistors/Mosfets and heat shields, which seems to be the norm with these and similar products.
Made to a price of course.
I've had to add it myself.
16min - So glad I'm not the only one who forgets which way to turn the lever for Close Ups or Wide Angle.
nice video... It looks like you know exactly how these things work, I just got one a 900w Im planing on making a low laying fog machine, heat up water and spray it on to dri ice, Im planing on reduce the diameter of the coil to about 1inch and increase the number of turns so I could increas the heating area.
keep up the videos... 👍
Really a very thorough explanation. I was looking at these because they are very cheap way of induction melting. Now I have to find a better power supply
Thanks for watching.
At 180 khz, skin effect depth of copper is 153 μm or just 0.153 mm of the skin of your 10 gauge wire coil is actually conducting. I'm peaty sure that is the majority of the cause of the heat in your copper coil.
Rough calculations:
10 gauge wire has diameter of about 2.58 mm or a cross section of 5.26 mm sq. If we subtract skindepth 2×.153 mm from the diameter, then you have about 2.28 mm diameter of copper wire providing support but not conducting. That works out to about 4.09 mm sq or 78% of the 10 gauge wire not conducting.
You may get far better performance from a litz wire coil with the about the same copper cross section as the 10 gauge wire.
While 24 gauge wire still has some skin effect at 180 kz , a much larger percentage of the copper wire is conducting. 25 strands of 24 gauge magnetic wire twisted on each other should almost equal The copper cross section of one strand 10 gauge wire, but will conduct far better.
25 stranded litz wire could be simply made by twisting 5 stands together into one long wire. Cut it in fiths and then twist those 5 twisted wires into one litz wire for your coil.
I join Bora's coment about your very clear, comprehensive explanation of the technical details. Thank's for making such a nice video.!
You are vey welcome, and thanks for watching.
You'll find solder won't heat readily with these units. They don't switch fast enough. Work around by using a graphite or steel crucible.
AvE blew his up by starting up the unit with the load in place. Doing so damps down the inrush before ringing can establish. See the next-to-last item in the seller's list of notes.
*excellent video. Thanks for sharing.*
You can wind a larger coil if desired without much problem. The main issue is pumping enough power into the unit to make it melt the aluminum.
This unit is basically a toy. But if you have a power supply around 50 volts and 30 amps is should just be enough to make it work.
so... 2 microwave transformers rewinded.... cool project...
For those using graphite crucibles, be aware: Graphite becomes more and more electrically conductive as temperature increases, which will divert inductive heater energy away from your crucible contents. Using a too-large graphite crucible may be fine at low temperature, but when it gets hot it will "act bigger" and there is where you may blow your heater circuit. My advice is to use conductive crucibles only when necessary, such as with powdered metals or other poor conductors of electric current. Consider using properly-sized non-conductive crucibles with a piece of solid metal or graphite inside as a "local heat source". Choose a material which will not chemically react with the material being heated, unless that is your goal. Here is a page of some experimental audiophile discussing the temperature/resistance effect of graphite in terms of everyday temperature and resistance units. Note graph at bottom of page: www.troelsgravesen.dk/graphite.htm
What a great tip..
Thank you for watching, and thank you for taking the time to send a note. Really makes it worth the time to make the videos.
I don't know anything about electronics and therefore have no idea what this video is about but it sure was interesting to watch.
No wonder mine doesn't work well.
Thanks for dedicate your time help others see a very important point.
May I ask if I use a switching stick welding (MMA ) typically 54VDC as a power supply, would it damage the chip. Suppose my fans can handle the voltage.
That was an excellent video! I have one of the Chinese induction heaters and you probably just saved me a lot of grief. Thanks for taking the time to post this. Greetings from Arizona.
Where at in AZ. Prescott Valley for me.
@@Brokendiode I'm in Apache Junction.
Thanks for watching, and thanks for the nice note. Actually having fun making these when I get time. And yes, many ways to make a supply. A little imagination is all it takes.
Fascinating heads up
PSA... if you decide to water cool the unit be sure to place the pump after the radiator and before the coil, you want the coolest water to run thru the pump... also, a cap and SCR is a kewl way to "jump start" the system, use a push button to get the gate to trigger the SCR.
One of the projects on my back burner is a flyback transformer Plasma Speaker.
those are easy n fun!!!
great mosfets at motherboards...
Really nice video. I always wonder if these Chinese induction heaters/zero voltage switches are any good. Your diy coil is probably heating up even more through the skin effect: All the current is flowing on outer part of the conductor with that high frequencies :)
Super neat video. When you think about it fourier wise slow rise time= little high frequency content which is what that LC tank will respond to.
That's if you wanna call 200kHz "high frequency"
Make sure to spread the coils out. If they are touching it lowers the inductance and results in overheating the circuit. Otherwise these little units are really handy to have. Most of what I heat treat is small enough to fit through the coil. You can use a foot switch and only have the unit on when you are actually heating something. Neater, easier and nowhere near as hazardous as a propane torch. It's a good idea to rig an old computer fan and you can rig up an SCR control so you only make as much heat as you really need.
Hi Lawrence, they certainly are handy, and cheap to boot. Aware of the coil issue, but that is good information to pass along to the viewers. Never thought to mention it as it is second nature to me. Thanks for the tip/reminder.
What an excellent demonstration. Thank you.
Thumbs UP! Very good tutorial, thanks. I am looking at buying an 1800 Watt one of these and having read the ebay add was confused about the supply voltage rise time.
I would have cooked the thing first go had I not seen this video. I like yourself have and want to use a Variac to control the output/heat so again this was the perfect video for my education.
Thanks again, cheers from John, Australia.
PS Just Subscribed.
Hi Joandar, Your welcome. Thanks for stopping by.
This is pretty cool. I'm looking into a fun alternative to my propane blacksmithing forge.
Honest comments, you're a tribute to humanity.
His home-brew version is similar to early inverters, which used simple SCRs as the power switching elements. The oscilloscope views showing the DC-separated AC half-cycles give a clue to how SCRs were made to turn off... zero current flow does it.
Thank you for the explanation on the power supply rising time!
You are very welcome. And Thank you for watching.
Wow love the test gear you have! Now I understand why I blew up my Chinese ZVS unit ...thank you.
Your Welcome, thank you for watching.
That transformer and capacitor you found..Brings a tear in my eye..How come i never find those!
I have a chinese induction heater, but I do not have a power source. What I do have, is 3 car batteries which I can put them in series and get 36v, will it be ok?
George Moraru try it
@@duckguide4109 Yes, that will work.
Good job on clearing up item 9
Very interesting video demonstration! What a model of capacitors they are, exactly! Voltage and current supported by capacitors! Thank you very much!
Nice demonstration,
What is your suggestion, if I use this circuit to build a cooktop which can run over 24v through solar panels....
My idea is to get solar power directly and utilize it for cooking purpose...
Here in the U.S. we have a home improvement stores ( Home Depot and Lowes ) both sell them. Just do a search for counter top inductive cook stove. There are many.
Have you looked at the specs of these cooktops to see if scavenged cooktops components could be repurposed?
I enjoyed the video as it delved in depth very clearly without unduly going to town on the actual circuit function.......nice to know that if you "invest".....it's a fun thing, innit?........ in one of these devices from China you'll get your money's worth as it will work as instructed.
Based on this video I'll try and source the higher power one...... I might as well now it's known that it can do some magic smoke raising......more power iz guut, ja?
I just can't be bothered to try and make one when you can get one that will work out of the box.
What you are saying, BUT an automotive coil fires as the magnetic field collapses when the points are open. The capacitor is across the breaker points, not the coil unless you are trying to say it's a series tank circuit, but that isn't what you are saying. The 12 Volts is attached to one side of the coil primary the other side goes to through the breaker points to ground. The primary of the coil is "charged" when the points are closed, building a magnetic field around the core and saturating it. When the points open that field collapses inducing a high voltage into the secondary of the coil, also, a lot of coils are one coil with the primary nothing more than a tap places close to one end of the coil.
Your parallel tank circuit needs to be very close to resonance at your oscillators frequency. For it to ring at a given frequency it has to be tuned to that frequency. For it to ring the cap has to charge then it discharges into the inductor, then back and fourth. That's what the ringing is. To maintain the ringing the energy loss must be replaced by a "kick" or a oscillator at the proper frequency.
Thanks, a nice video. Why are the transistors not interlocked so they cannot turn on together? I've spent many years working on commercial inverters (usually H drive config) and no matter what happens at the battery end they will not get locked up. However one drop of condensation on the PCB.......
Outstanding video. Thanks for explaining everything so well.
HI Ian, Thank you. And thanks for watching.
This blew my mind, thank you for this video
My mind has been gone for a long time....Your welcome....
regarding the ignition coil
the spark occurs when you interrupt the current and dissipates the energy stored in the magnetic field of the primary coil. the capacitor is there to tune the primary to the frequency the secondary has with its stray capacity so effectively turning the ignition coil into a resonant transformer (tesla coil)
Think that is what I said, and why I used the scope to show the secondary oscillations.
when switch ON is fast enough, asymetries in the two legs cause the LC circuit ringing and thus start the oscillator, while switching OFF causes the ign coil with its capacitor ringing until the stored energy is used up by the spark which effectively short circuits the secondary and stops ringing
but okay lets leave it at that
Would like to make an induction sewer cooker, with cast iron pipe. Septic is expensive, but human waste can be made safe if heat treated. Solar/wind plus induction seems to be a good choice, as one often needs an energy dump. Would be much better for the environment. Septic systems can cost between $5000 to 10,000 dollars. Would seem you could burn poop for far less, and make it safe for fertilizer .
I believe that is what some of the city sewer plants do. They filter, burn/cook/heat then spread it on newly seeded construction sites. Grass grows like crazy.
If you want to see a decent induction furnace visit an aluminium smelter, we have had one here in the state located at Bell Bay, Georgetown, Tasmania, since the sixties, originally Comalco aluminium, you need your own power station to run it. excellent video and commentary thanks..
Your welcome. Thanks for watching....
You probably do need your own power station or a very good deal with a local one to run a primary smelter, but for remelt the power needs are much, much lower.
First
Thank you for the full explanation
It Worked efficiently on 12 volts
Its connection to 40 volts burned the mosfet
I don't understand why
Hello, I think the maximum voltage stated by the manufacturer was 36 volts. I try to keep mine in the 24 to 36 volt range.
You explain topics very well on your videos. I enjoyed the comparison you did here. I will view your other videos as time permits. Subscribed.
Thank you for the nice comment, and thanks for the subscription. Vern
Thanks for the nice comment, and thank you for the subscription.
21:29 thanks for that annotation, that was exactly my question on another ZVS video
Thanks for watching, glad I could help.
As a Fellow Ham, I am surprised you did not mention the wideband interference these cheap devices can create if not properly filtered and shielded.
Lets face it. These are basically toys that get used a couple of times, blown up and that is the end. The real issues these days are all the crappy switching wall warts, crappy led lights and all the other cheap consumer junk from China that runs every day most of the day. That is where the R.F. Noise Floor is coming from.
V. Informative video. I am glad to come across your video otherwise I would have blown my Chinese circuit right from the beginning.Thnx
Your welcome. Happy to have helped.
Thank you for giving me some really great ideas on improving this heater. Peace too.
Question: Do you think it would be possible to run the induction heater by using a Peltier - (TEG) generator? (using a stove as heat source... Just curious...
Possible? Yes. Practical, no. To get any real power out of the unit you will need 48 to 50 volts at around 12 amps. That is a pretty big TEG unit.
Thanks for the information and excellent video you are very good at explaining each process.
Your Welcome, Thank You for Watching......
Hi RM, Would this Chinese inductor be suitable for use on 13mm exhaust bolts? I would also like to use the wire type coils as used with "bolt buster" and the likes due to the location of the bolts, is that possible? I see that when use the inductor you don't use cooling, is cooling necessary? If cooling is needed can you point me in the right direction? As I would be using the device as a "mobile device" is it possible to fit a case for handling? If so can you recommend a case? Would the smaller unit be adequate for the job I'm doing? Finally can you recommend a cheap power supply? Thanks in advance, Mark
Would attaching a switch to my 12VDC supply battery be sufficient to have a fast rise time pulse, or would the minuscule bouncing of the switch being put in the on position wreck the circuit too?
Thank god i was watching these induction videos before i used mine otherwise it would have exploded XD
The best chinesium money can buy! I am interested in building a brass annealer out of one of these in the future. You should do a video with your explanation of how an automotive coil works for some of the younger folks that don't understand exactly how it works. understanding an automotive oscilloscope and what the patterns mean is becoming a lost art. Just to make sure my understanding is correct, the power supply itself will have to slow of a rise time if your switching on the primary side. So the ideal is to power it constant, and have any switching on and off of the inductive heater circuit should be on the secondary side of the power supply correct?
Oh nice I just left Manch a lil over a year ago, coulda had some great project fun you may have seen me in the local clubs (if ever in any) working on the pool tables for the haunts! Anyway great vid!!
Thanks for sharing. Very informative/educational and very good setup. You are absolutely right about capacitors. Inspiring me to go out and try again! Kind Regards. Pablo
Your welcome....
I want to buy or build something like this to heat 1/2" x 1/2" square stock so it can be bent in a hand scroll bender. I have several high wattage 24 volt omron industrial power supplies, do you think 24 volt supplies and this Chinese induction heater would be powerful enough to heat a 2-3" of 1/2" square bar. Thanks
If you don’t mind can I ask a question? If I wanted to temper some steel and the curie affect starts while it’s only cherry red how do you get up to those sort of white hot temperatures needed before quenching it?
You can have a slow rise supply and use high capacitance capacitor at output to kick on the oscillator too.
The sharp inrush is needed to start the coil "ringing" otherwise both transistors turn on at the same time and blow up. The capacitor ( if after the switch or relay ) will delay the voltage rise causing the same issue. Putting the cap before the switch will also cause a slower rise in voltage as the cap charges. The whole trick is to have full voltage at the switch closure.
Very nice video !
Congratulations !
Well stated explanation of tank circuit. Might refer others to this vid just for that.
Is it possible to modify this for PDR (Paintless Dent Repair) like the PDR T-Hotbox? Obviously the wiring for the horseshoe probe would be needed.
I just bought a Chinese inductive heater. It did not come with a coil so I decided to watch a few videos before powering up. This is the first video and i must say its a good thing. I was intending to power with a computer power supply and I have a tendency to just use the switch on the device. It definitely takes some time to come on full when switched on. I never considered this would have been a problem.
So that comes to my two questions.
1) if I power on the computer power supply and let it come up properly then use a switch in between that and the inductive loop will I get fast enough switch on?
2) Since no loop was provided or any info on the size what inductance is good. Seems everyone does a few loops but the variation seems be large (2 or 3 loops to about 8).
Btw this is the first channel I subscribed to after watching one video. Normally I watch a few before making that decision but this video was so clear and properly explained that I was convinced you have good content.
Hi Manic,
Yes, you can turn on the supply then use a switch to turn on the unit and you should be fine. Be advised however the switch needs to be rated for a lot of current. The problem with DC is the arc does not quench when the switch opens unless the switch contacts have a lot of open clearance.
As for the coil, ( I am on the road right now and cannot measure the coil ) this is not real critical. Note how many turns mine has and make the coil about 3 inches in diameter and you should be fine. I strongly suggest you make it out of copper tubing at least 1/4 inch diameter ( 6mm ) to handle the current.
THANKS FOR THE GREAT VIDEO!!!!
I am somewhat new with ZVS. I have the ebay ZVS board. I need a "final" output of about 600VAC peak at 10A max to connect to a fullwave bridge made of four SiC diodes. What do you suggest I use at the ZVS output...perhaps a type of HF high current transformer??
If you add a secondary winding to your output consisting of a big step up coil you'd have a Tesla coil! I've never seen a water cooled Tesla coil though.
Lot of folks have done that. The reason the tube is water cooled is that the coil is passing very high circulating currents. This causes a LOT of heating in the coil. Tesla coils pass along a lot of that energy into the secondary.
Very Nice Bro,
Your spark plug analogy needs a little clarification. The capacitor in an ignition system isn't what causes a resonance, the reverse EMF from collapse of secondary windings induces a 120v to 320v pulse in primary coil. ( you need a PVA for meter to measure it) When ignition is triggered on next rotation, you get a better spark with 'longer' duration
In a simple coil/points ignition the capacitor does indeed produce a resonant circuit prolonging the spark. Trust me on this. Try it yourself. This has been known for 75+ years.
And yes, there is inductive EMF. This is what charges the cap and prolongs the "ring" for the hot spark. The scope pretty much proved it. Resonant inductive/capacitance circuits have been around forever.
Hi, I may be a bit late to the party, but what do you think about microwave capacitors? They should be suitable, aren't they?
Also, I thought about getting an old induction cooker and scrapping it for parts. Since its the same technology I think it should work. Basically I just need to wind a new coil and get around the cooking exclusive safety mechanisms. Or am I dunning krügering it and its more difficult?
More than 10 minutes repeating why the Chinese induction heater needs a fast rising power supply voltage. The demonstration of the arc in the spark plug is clear, as the scope display. The 'tank" oscillator produce many arcs which explain the large bright arc instead of the wimpy purple arc.
About the transistor explosion: The hypothesis is that both transistor will conduct at the same time, short circuiting each other.
Another possible explanation is internal hot spot in the transistor that can happen if the gate voltage is too low to force the transistor into saturation.
great video, can you just a use longer coil with double number of turns ?
Check current prices on e-bay. Search ZVS Induction heater.
The Radio Mechanic UA-cam h
male your own, look at those beautifull 55a 25V mosfets at motherboards, they're PERFECT for making zvs's.
Do we actually need both transistors?
Can't we just oscillate the tank circuit with something equivalent to a not gate. Similar to a pierce oscillator, but using the tank circuit instead of a crystal?
Thanks for this informative video (I'll definitely be checking out more of your vids!)! I was waiting the whole time (since you are also clearly a fan of analogies) for a "ringing the bell with the fast rise-time of a hammer hit" analogy, and that attempting to do a soft-start was like hitting the bell with a soft object, this just wouldn't have the high frequency component to excite at the resonant frequency of the tank! (Spoken as a radio amateur also of course!)
...great explanation (if not one of the best I've heard, and another great analogy!) and use of the automotive ignition system, also! 73 KA1-RBP
Will it be possible to melt silver for casting in a 1000w unit or do I need one that has a higher power?
Thanks, that was most informative. I watched the whole thing through.
Thanks for watching and the nice words. A nice counter to the comments from "Daite Dve" who said to me quote "Dude you are Soooo Boring." Cant win them all. :-)
Which one is better between the Harborfreight 750 watts inverter and Chinese 1000 W ZVS induction heater?
Excellent comparison. Immediatelly subbed to your channel. Keep good work!
Thank you, appreciate the support.
Hi Radio Mechanic, why doesn't the work piece move under application of the magnetic field ? I would be worried that the work piece (or the induction heater) would have a rapid and strong movement to maximise flux linkage - parts could topple over, vibrate, spill etc. due to movement.
Excellent question, and the answer is - it does! If you look at the video about soldering PL-259 connectors, and even with the video about the solder pot you will see the solder jump up when the relay turns on the DC power (after it is molten). Small pieces of aluminum in a crucible will "stand up" when the power is applied also. They try to align with the magnetic flux down the center of the coil. The force is not extremely strong, but is present. There is a video on you tube ( forget the title ) where the first three turns of a large induction coil have been reversed. In the video the work piece "levitates" in the field until the part becomes molten and looses magnetic properties, then falls through the coil.
My question would be how can I modify it to make it handle more power. Better transistors, any suggestions? More caps in parallel ? Can you put two transistors in parallel, say two on each side? I just picked mine up from china and it works a treat. But I want more. My psu goes up to 56 volts @ 12a, but I've got it set at 48 for now.Also what affect would having the coil on the end of a long 1m cable have? I'm making mine into a handheld unit to heat up rusted nuts on cars for easier removal.Also what design of coil is the best? One with more turns of thinner guage wire, or just a few thick coils.
i was debating on purchasing a Chinese unit but inspiration to build my own.
Hi Thomas, the parts would have cost me what the unit cost me delivered. And if it dies I can modify it pretty simply. Was mostly purchased as a toy. Thanks for watching.
thanks, it is a nice video. Just if we use two boards and the output link to one coil. is this way increase the watts to 2000w
Thank you very very much for sharing your knowledge and pointing out the point no. 9 which I did NOT understand before watching your video.
Question. Do I also need a capasitor after poer suply and before second swith/relay/timer?
If yes, what capacity is needed for about 48-50 output volt from power supply?
Regards
Hello, no I don't have any caps after the supply. I just turn on the supply then turn on the power to the Unit. Thanks for watching.
Wow, thanks very much, I have just learnt a lot just now. Thank you very much
Radio Mechanic,
Yep seen many Chinese crkts costing less than the parts here in the US. Just goes to show how much profit the distributors are making. You know they are getting their components from China as well. Thx for sharing videos take a lot of time. Now as to the heating in your coil vs the Chinese unit. It is simply due to the skin effect. The current is only a one skin depth and their tubing has a larger circumference than yours by what say twice? Just a swag. This means the current density is lower in theirs vs yours.
Next is more of the screw is covered by the taller coil, theirs, so more of the screw will get heated and the current drop due to the Currie effect will be larger.
Thx again for sharing.
As for the fast risetime start up, try what the CFL guys do, they use a Diac to generate the impulse needed to get their crkt working. You would have to create a mod that keeps the crkt from operating until it gets pulsed. Looks like it could be a great solution to the tricky start up problem.
Paul
HI, the skin effect is seriously present on both coils. The circulating currents are also quite high. The coil made from tube, while a little slower to heat, heats quickly to the point of blistering and will turn brown/black within a couple of minutes. The reason it is staying cool is the water circulating through it. Without the water the run time is very short. The wire was around 3/16 ( .187" ) diameter and the tube is slightly larger at .200" diameter ( less than 9/32 or .218" ). The wire has more mass to absorb the heat so the temperature rise is fairly close as the thin wall tube does not have the heat capacity. But yes, skin effect is certainly in play here. Sadly we are dependent on cheap Chinese stuff in this country. Would pay a little more for U.S. goods if they were still made here. Sad state of affairs. Thanks for watching and the great comment.
I want to melt and make bars out of scrap silver and silver plate, so will the Chinese model melt silver..? I also have another question could you not recoil the copper pipe into a bigger opening maybe even use say 3 units together so a new copper coil wrapped up into three units into one....?
How much frequency & power do I need to heat up metal whose diameter is more than 60 mm? I want do it within 2 minutes..