Hi Richard. The Video turned out excellent :) and thank you again for having me on your channel. looking forward to our next collaboration . And guys we haven't forgotten the Oscilloscope comparison video!!! just waiting for deliveries have a great day Richard
You inspired me create a microohmmeter out of my DMM using a USB cable, narrow perf board containing LM317T & 12.5 ohm resistor, and red/black clip on leads. Really compact, sleek, and handy - after I shrink wrapped the board! All I do is plug in the USB cable which is attached to one end of the PCB, clip on the kelvin probe leads attached to the other end of the PCB, and set the DMM to measure mV. Whatever result I get, multiply by a factor of 10 (move the decimal place) and the result is precisely milliohms. The factor of 10 is because R = V/I, where I = 0.100 A, because Vref(LM317) = 1.25 V and R(adj) = 12.5 ohm. The 12.5 ohms was accomplished with three common resistors in parallel: 15, 82, and in my case 680. The last resistor is something under 1K just for tuning out the tolerance variation of the lower resistors and voltage regulator Vref. I could have used a 1K potentiometer instead of the fixed resistor. All components were "in stock" so it cost me $0. Thanks for the demonstrations on this topic, I learn a lot from you!
PCB have been in touch several times regards sponsoring my channel. I have to give credit they do support UA-cam content providers really well. They do provide an excellent service.
Just so happens I “specialize“ in stuff like this, as I have my own small business and lab focused mostly on component level board repair for metrology and manufacturing/research equipment. But I love collecting weird/gimmicky test equipment Devices… The strange and quirky things like used to be sold in the back of electronics catalogs in the 80s and 90s 😂 Iv got dozens and dozens in my collection and some of them are hilariously useless…. but some of them work quite well, And can even be the most used and valuable gadgets in the lab. If you haven’t seen the “leak seeker” by EDS… In my opinion it’s the best low resistance short finder that’s ever been. I’ve owned ALL OF THEM, From the cheap DIY versions up the the really expensive versions like the “Polar Tone-ohm” and “Huntron Trackers”. The “Tone-Ohm” units are pretty good if you can get them at a fair price. Even their cheaper versions will bring a couple of hundred dollars and the top-of-the-line versions with all the probes will be quite a bit more. But I’ve been lucky enough to snag at least one or two of each version over the years. But the functionality and unique circuitry of the “leak seeker 89“ far surpasses anything else in my opinion. I’ve built several from kits that I keep in and around my lab, and I’ve even snagged a few of the original/old versions on eBay. Dave Miga is an incredible guy and designer… He’s also the original designer of the ESR tester known as the “Cap analyzer 88A”. It was designed decades ago and was the first in circuit ESR tester design on the market… It was so good that Even the big boys like BK precision and others copied his original design. There are many Other low ohms/short detectors -the “half-ohm” multimeter adapter… Available on tindie for about $15. -the “shorty” -“short sniffer” -wavetek sf10 I could keep going as there are many that have been on the market or custom designed over the years. There are also devices called “short-circuit killers“… They don’t just find the short but they overload it with current therefore destroying it and in most cases restoring the board back to working order. It’s kind of a weird approach but used pretty commonly in the cell phone repair and laptop motherboard repair business. If you haven’t seen them just look up “short killer“ on Google or UA-cam… It’s kind of a weird approach but it seems to work for a lot of folks.
The cutters have a flat bottom side while the top are tapered., thus will want to ride up on the insulation and slip off. The insultation is actually being cut on a bevel as well when held right way up. When held upside down the bevel cut is on the insulation that stays and the flat cut is on the piece you want to remove.
Stripping using the sidecutters backwards is something I was taught as an apprentice in 1976 - still do it to this day - don't even own a pair of wire strippers
Great little project! ... a suggestion for another project is another type of probe I found really usefull when I started out (and still use it sometimes) ... is a simple audio probe for signal tracing. To go with it you could also build a tiny battery powered amplifier from e.g. a TDA2822 (only a handfull of cheap parts) or similar and add a tiny speaker for use with the audio probe. This gives a very useful tool and also an introduction to amplifier building for e.g. headphone amps ... :)
Hi M8, So if i understand you its audible signal tracer . interesting i have seen something similar used in car repair but it was for hearing knocking and other irregularities on a car engine, via a stethoscope looking thing with a amplifier and a time scale reducer (took 1 sec and stretched the audio 10X(as normal sounds from the engine are are at 1k-5k rpm. this made it possible to hear scratching and other irregularities. OK don't with the rant . So hmm. if we do the same for electronic signals we should have a specific sound/audio for different types of signals and if we slow it down (because we can't hear frequency over 6-20k hertz so a single over this would be in-audible ) but if slowed down we should even be able to hear ultrasound. just an idea don't have a clue if it works :D
@@RetroUpgrade Hi Retro ... yes an audible probe (with in series capacitor for DC blocking in case you probe something you shouldn't by accident) housed in an old writing pen body for ease of holding. Usually used for audio equipment, you inject e.g. a sine wave signal into the circuit then trace that signal through the circuit with the audio probe listening through another amplifier. I have many oscilloscopes here but still use my little audio probe at times. I made a tiny battery powered 2watt amplifier from a TDA2822 and used a tiny old scrap car speaker (in it's pod housing and built the tiny 2822 circuit board & battery into this too) for the output so the probe and speaker are completely isolated & hand held. It's a good alternative to an oscilloscope sometimes. You've got some interesting ideas on a variation ... :)
@@johnnybravo505 This is something I have in mind to do. I demonstrated a kinda ghetto version of that already just using PC speakers and a capacitor - I also used the same device to test if a motherboard or GPU is accessing the BIOS ua-cam.com/video/2pAp1R24XyY/v-deo.html ua-cam.com/video/0hWnkRl3t1Y/v-deo.html
@@LearnElectronicsRepair Yeah I thought it would fit in well with the kind of simple & cheap but useful tools your making regularly, especially if you can make it really small and handheld (I think you've already covered a small sig gen) and the same circuit with a couple of changes doubles as a perfect headphone amp circuit (and sounds great if you power it from a 9v battery). I used an old car speaker backseat parcel shelf "pod" from the 1970's that I found in my workshop when I moved in for speaker and housing (just didn't want to throw it out) but any small speaker could be used to make it a lot smaller. I look forward to your spin on it & you could get your mate Retro to design & print a housing .... :)
I found your channel through Hackaday where the tester video link was posted so its no suprise there are a lot of views. I do like how this project has evolved and I will be making one of these and powering it with Lipo batterys recoverd from disposable vapes. Keep the videos coming please :)
Thanks and Welcome aboard. Have a look at the LER discord server, you may like it Learn Electronics Repair is now on Discord! Come and join the fun, it's free. discord.gg/vam6YC8vwU
Just ordered some of these, I had a look at the option to have them do the assembly out of curiosity (I'm a beginner and won't learn much by getting someone else to assemble it) and it was £30 so definitely not worth it for a project like this at least, maybe for larger projects it could be more viable. I had an idea while watching this that might make for an interesting series but I'm not sure how possible it would be. I was thinking of all of the basic equipment needed to start in electronics repair as a hobby, and a lot of them have DIY solutions of varying usefulness floating around on here and I'm sure elsewhere. It would be brilliant to have a beginners course of sorts where you could walk the newbie through building some of their own equipment while introducing and expanding on some basic concepts in real world, useful (and potentially money saving?) examples. Sounds like a lot of work but food for thought I reckon.
Thanks guys for an interesting video. As a former calibration & measurement technician I find it very easy to modify this circuit even further - to a DeLuxe version meeting precision specs for an accurate plug-on milli-ohm meter device to your medium hobby multimeter. That's another story, as this circuit was purely made up for tracing shorts on PCB's. Thumbs up 👍👍
Thanks a lot :) if you point us in the right direction i can give it a go and modify the Circuit so it meats industri standard specs. be aware that i don't have a formal electronics degree 😜 so be gentle with me 😆
CXensation - why not post it on Discord Sponsored projects section - we can get some free PCBs made and send to you, if you are OK to publish the project 🙂
@@LearnElectronicsRepair My arthritis in my hands disallow me extensive use of the mouse for circuit drawing. But I will take a discussion on a precision circuit with Retro Upgrade.
@@RetroUpgrade First off - we need a "kelvin" switch not to introduce offset voltages here - like a good quality gold plated contact switch. The switch must be a slide contact point type to be self cleaning. Remember that the measurement current passes thru the switch ranges thus affecting the indicated voltage ... The ranges should be 20-50-100 mA - because most multimeters already have a 10mA range for their lowest ohm range. The range resistors should be E96 1% types and the values should be corrected for the LM117 bias current, as this always passes thru the DUT (device under test). This is done using a calibration procedure where you measure the voltage over a precision resistor, and then modify the range resistors to get a correct reading. 1% 10ohm and 100ohm resistors leaded type should do. The voltmeter must have an accuracy of at least 2% on the milli Volts scale. ... that should give you a milli ohm meter prescaler of some 2-3% accuracy, which is Hi5 for current sensing resistors 🙂
great upgrade looks pretty cool :) would love to see the revisit videos to all the ideas in these comments :) also fantastic news about the sponsorship from PCBWay :) great colab too hoping for more :)
The community thing is the way to grow. People are already picking it up on youtube. Give it a go with a split screen video with you and Carlos/Detlef on a project.
The point of kelvin probe is to measure the voltage at the absolute last point of contact for an accurate reading, that's important if you want to read the actual resistance, for short finding that's not important, the important thing here is a better connection for current to flow, I found that a pointy tip is much better for that, IMO a thin multimeter probe with the current wire soldered 1 CM from the tip is a better, more accessible and convenient solution for short finding. Inspired by your first video I built my own circuit with a toggle switch toggling between 100mA trimmed with a 10 turn pot (useful when I want to measure actual resistance), and an adjustable one using regular pot paired with a transistor that is able to get up to about 500mA out of the 317 regulator, using this high current added more resolution and made it easier to find shorts in a close range.
Mohamed Gharib That's good to see you were inspired by my original version - this is what all this is about IMHO. Your version sounds very useful. For whatever reason the version with the kelvin probe was the most stable and highest resolution (it worked on the 1mA range) but this could also be attributed to the use of batteries as a power source. I have and idea in mind that may have the combined advantages of kelvin clips and sharper points, and is cheaper than kelvin probes - I will be testing that on an upcoming video
Hey Richard I just ordered the pcbs unpopulated. The reason they wanted the extra file is because I wanted to order the board with components populated.
Excellent. Very nice. I think it would work very well without a constant power supply. If we have a 5V source and use instead of the current limiter a single resistor of 100 ohms for 50mA, 47 ohms for 100mA we will get the same results. The resistance we measure is small, below an ohm and then it does not affect the current so much and we will have almost a constant current source. For overvoltage protection, a silicon diode can be placed in parallel with the testers in direct conduction, which will limit the voltage applied to the circuit to 0.7V.
It would not work with just a resistor as the current through the short would vary too much depending on the short 'resistance' to trace it accurately. This tester relies on accurately measuring voltages down to 0.001mV - the resolution of my Aneng 8008 meter. Fortunately LM317 cost almost nothing, and are easy to find on scrap PCB to salvage. As an aside this would not work with a bench PSU set to 50mA either as there are large output capacitors on bench PSU that dump a large instantaneous 'discharge' current spike into the device under test (that the PSU can not control/limit) every time you used your probe This device does not need a diode or anything else to limit the output voltage to 0.7V. Just like your multi meter on diode mode does not need a voltage limiter even though they usually output 3.5V-4V with enough current to light an LED and we all happily use meter on diode mode to poke around GPUs I proved this emphatically on this video with theoretical and practical demonstrations. This 5V device will NOT damage a GPU or CPU! I also proved a bench PSU at 50mA can not be used in this way and *will* blow components ua-cam.com/video/XEbWyQgX_Mc/v-deo.html Give that a watch then let me know if you still have any concerns regards the voltage used to test. 😉
Thanks for the reply. I'm totally agree with what you said. I saw the other clips related to measuring small resistances and short circuits and you are right. A voltage limitation would only be necessary if the short is measured in the case of circuits that consume very little current and have high resistance. Diode voltage limitation has the disadvantage of consuming batteries if a battery-powered source is used. Great and useful videos regarding short circuit finding: ua-cam.com/video/0eixDdCpiO4/v-deo.html ua-cam.com/video/P_2GGNr4q1s/v-deo.html ua-cam.com/video/XEbWyQgX_Mc/v-deo.html ua-cam.com/video/i8TudEfD2Ao/v-deo.html ua-cam.com/video/kGM-Zmrr6tc/v-deo.html ua-cam.com/video/NUgO7v4cbKs/v-deo.html ua-cam.com/video/GCHM_svGO4Y/v-deo.html
@Max Mini I think YT may have auto deleted the links in your reply (or the whole reply). Sorry if that happened it's not me. I can see the reply in my feed but not here copy/paste Max Mini Thanks for the reply. I'm totally agree with what you said. I saw the other clips related to measuring small resistances and short circuits and you are right. A voltage limitation would only be necessary if the short is measured in the case of circuits that consume very little current and have high resistance. Diode voltage limitation has the disadvantage of consuming batteries if a battery-powered source is used. Great and useful videos regarding short circuit finding: ua-cam.com/video/0eixDdCpiO4/v-deo.html ua-cam.com/video/P_2GGNr4q1s/v-deo.html ua-cam.com/video/XEbWyQgX_Mc/v-deo.html ua-cam.com/video/i8TudEfD2Ao/v-deo.html ua-cam.com/video/kGM-Zmrr6tc/v-deo.html ua-cam.com/video/NUgO7v4cbKs/v-deo.html ua-cam.com/video/GCHM_svGO4Y/v-deo.html
Thank you. It must be an error so I will try to post the reply again. I'm totally agree with what you said. The usage of a constant current source will provide more stability, cancels out the unwanted effect of the power supply voltage variation, extend the range of measurement and also will give us the reading of the real value of the measured resistance knowing the exact current that is used during the measurement. A diode voltage limitation would be necessary only in rare cases of circuits with very low power consumption and high resistance, but it has the disadvantage of a high draining batteries if a battery-powered source is used. Here are some other great and useful videos that I liked very much regarding the short circuit finding: The Amazing $1 Short Finder Upgraded! Convert your multimeter to a 4 lead Kelvin Probe Short Tracer ua-cam.com/video/0eixDdCpiO4/v-deo.html Convert Your MULTIMETER into an accurate SHORT CIRCUIT TRACER Finder for less than $1 Build This DIY ua-cam.com/video/P_2GGNr4q1s/v-deo.html The $1 DIY SHORT CIRCUIT TRACER Part 2. Will a 5V short finder kill sensitive components CPU GPU? ua-cam.com/video/XEbWyQgX_Mc/v-deo.html How To Find Short Circuit VRM MosFET With An ESR Meter ua-cam.com/video/i8TudEfD2Ao/v-deo.html Learn Electronics Repair #13 Short Circuit Tracing Techniques (8800GT Part 5) ua-cam.com/video/kGM-Zmrr6tc/v-deo.html Learn Electronics Repair #15 - Short Circuit Tracing part 2 (8800GT) ua-cam.com/video/NUgO7v4cbKs/v-deo.html MicroOhm Meter Short Circuit Finder Review Comparison Vici VC480C+ vs YR2050 Milli Low Ohms Meter ua-cam.com/video/GCHM_svGO4Y/v-deo.html
Hey guys - nice to see the project keeps evolving! Just one thought: 2 CR2032 instead of the bukly AA or AAA cells? We should get enough current out of those, and with 6V we have enough headroom even for slightly discharged ones. @Carlos: great housing!
Hi Detlef. And thank you for your generosity and helping us to move this on to the next step. Your work is most appreciated. 2x CR2032 would give more than enough voltage, but how long would they last if running on the 50mA range. I have no idea what the current capacity of those batteries is. ua-cam.com/users/DetlefAmend
Hi Detlef :), thanks a lot i worked hard on it :D it's actually parametric so i can modify it quite easily . but then CR2032 sound like a great idea could probably make a hosing with just the front part of my design would be a lot smaller and faster to print - 4,5h is a little to much for most ppl :P i'll do a draft model for the CR2032 and send it to you and richard for review :) think even we can fit the CR2032 on the back of the PCB no battery compartment needed Btw you have a new subscriber ;) , you do really interesting stuff
@@RetroUpgrade Sounds good enough to me 😁 That's what I find so good about this channel - lot's of knowledgeable and friendly guys giving their time and ideas.
Thanks for all those very interesting videos! I recently retired from testing & repairing medical electronic equipment. I built the “Amazing $1 Short Finder” using construction techniques very similar to yours. I put it in a repurposed minibox (from a discarded medical gadget) and used a 5 VDC wall wart for power. Without going into a long sob-story; How well do you think the short finder will work on a +55 VDC rail short buried deep inside a Tektronix 465 ?
The BoM posted on PCBWay does not contain the USB port, switches, and terminal block article numbers. As the PCB is designed to accommodate specific-sized components, would you mind sharing some article numbers for these mechanical components? Thank you very much in advance
Great project! How about a small enclosure with chassis mount banana plugs spaced to match the standard multimeter jacks so it just plugs into the meter when needed. Power from a lithium battery (rechargeable for the deluxe model) as others have suggested. Pogo pins make really good custom probe tips and if sockets are used they can be replaced easily - I have used them to make custom leads for my HP 4328A and HP 4338A milliohmmeters. Regards, David.
used to do this years ago if I could not find the miliOhm meter. 1A 1mV 1mOhm, no maths involved as long as the circuit could take the 1A. A very stable constant current power supply was a bonus. As i was normally checking connector backshells to chassis via EMC gaskets, there was no problem with the 1A.
Hi, welcome to the channel. That sounds useful for making measurements. Of course in the case of the short finder we don't actually need to know the actual resistance value - just where the lowest reading is. Why not pop over to the sponsored projects section on LER discord - we have some sponsorship from PCBway to work on projects and gadgets relevant to electronics repair. Everyone welcome. Learn Electronics Repair is now on Discord! Come and join the fun and let's fix stuff together, it's free and a nice place to be. discord.gg/vam6YC8vwU Sponsored Projects discussion discord.com/channels/896427792751820842/976398185629093948
I think just using 2 AA batteries with near 100 ohm resistor should do the trick. I have taken very stable and distinctive readings with this setup that pin point to the shorted component.
I ordered the USB version. The switches aren't in the BOM, so not sure what to get and the PCB is not the same as the one in this video. The one i ordered is too narrow to mount a usb port on.
Hi Richard - Just a thought about the battery's - Why did you not use a single sell £1 18650 5V power bank, then you would not need to keep buying AA's.
Personally 4 wires is better, but I think the kelvin clips are not needed, just two wires down near the probe point for voltage sense is enough, try it.
@@LearnElectronicsRepair Well you use USED the kelvin clips, I personally do not thing you need them clips, just solder the current carrying wires close (1/2" is fine) to the probe points, still 4 wire, no alligator clips needed.
@@user-rs8zg8ey2b For sure both methods worked - it is possible the battery version is more sensitive/stable purely because of the fact batteries are more stable than USB or bench PSU rather than due to the use of the Kelvin probes. I have an idea for a very inexpensive 'off the shelf' version of kelvin probe so when the parts arrive I will do a direct comparison between kelvin probe, attaching current wires to standard meter probes and my other idea on another video. Then we can all see what, if any, difference it makes 😉
@@LearnElectronicsRepair Great, will wait for the outcome, personally, the stubborn shorts I come across are on 20+ layer pcbs costing 3 to 5K, the DUT consumes up to 80A, I start with 100mA, but find I need to go higher on the current (even up to 2A), there is 2000+ decoupling caps on these boards.
To find shorts on capacitors? Yes. In the original video I showed the tracer is able to find one shorted capacitor in a bank of SMD caps all adjacent to each other ua-cam.com/video/P_2GGNr4q1s/v-deo.html
Hey Mark, here is the link where you could quickly get Richard's pcbs: www.pcbway.com/project/shareproject/_1_Short_Tracer_USB_Version_by_Learn_Electronics_Repair_UA-cam_Channel_f3ce0bdc.html
since youre not measuring actual value but only difference lead drop dosnt really matter as long as it is consistent (iow. kelvin probes/attaching at test lead ends is pointless). thus better solution would be lcr plug in style addon or even hacking the mm and using its power source and internal space
Hi. Is there som circuit inside the lcr probes that I am not aware off? If not is there a difference? Did a quick search for lcr probs and they range in price from 20-50€ for the cheap Ones and the cheap Kelvin probes cost in the range 3-15€ for the cheap ones. I am really curious. Am I missing something? (disclaimer I am a electronics noob)
I have another very low cost and less bulky option to the kelvin probes to try. It's still four lead though. I just have to wait for the stuff to arrive to try it
I just looked at PCBway, their way of searching project makes the site useless. there are over 40 pages of audio (most of them amps) and i never found anything that got my attention. Nice idea bad execution.
Yes I got this one too, works wonders. Measures capacitance in 1 second on any size capacitor even 10000uf or larger. Hower it needs some work as the only thing made without problems is PCB. The case, connectors are cheap china crap. Price doubled on my after replacing these components.
Hi Richard.
The Video turned out excellent :)
and thank you again for having me on your channel.
looking forward to our next collaboration .
And guys we haven't forgotten the Oscilloscope comparison video!!! just waiting for deliveries
have a great day Richard
It was a pleasure to make, And a good result 🙂
You inspired me create a microohmmeter out of my DMM using a USB cable, narrow perf board containing LM317T & 12.5 ohm resistor, and red/black clip on leads. Really compact, sleek, and handy - after I shrink wrapped the board! All I do is plug in the USB cable which is attached to one end of the PCB, clip on the kelvin probe leads attached to the other end of the PCB, and set the DMM to measure mV. Whatever result I get, multiply by a factor of 10 (move the decimal place) and the result is precisely milliohms. The factor of 10 is because R = V/I, where I = 0.100 A, because Vref(LM317) = 1.25 V and R(adj) = 12.5 ohm. The 12.5 ohms was accomplished with three common resistors in parallel: 15, 82, and in my case 680. The last resistor is something under 1K just for tuning out the tolerance variation of the lower resistors and voltage regulator Vref. I could have used a 1K potentiometer instead of the fixed resistor. All components were "in stock" so it cost me $0. Thanks for the demonstrations on this topic, I learn a lot from you!
PCB have been in touch several times regards sponsoring my channel. I have to give credit they do support UA-cam content providers really well. They do provide an excellent service.
Just so happens I “specialize“ in stuff like this, as I have my own small business and lab focused mostly on component level board repair for metrology and manufacturing/research equipment. But I love collecting weird/gimmicky test equipment Devices…
The strange and quirky things like used to be sold in the back of electronics catalogs in the 80s and 90s 😂 Iv got dozens and dozens in my collection and some of them are hilariously useless…. but some of them work quite well, And can even be the most used and valuable gadgets in the lab.
If you haven’t seen the “leak seeker” by EDS… In my opinion it’s the best low resistance short finder that’s ever been.
I’ve owned ALL OF THEM, From the cheap DIY versions up the the really expensive versions like the “Polar Tone-ohm” and “Huntron Trackers”.
The “Tone-Ohm” units are pretty good if you can get them at a fair price. Even their cheaper versions will bring a couple of hundred dollars and the top-of-the-line versions with all the probes will be quite a bit more. But I’ve been lucky enough to snag at least one or two of each version over the years.
But the functionality and unique circuitry of the “leak seeker 89“ far surpasses anything else in my opinion.
I’ve built several from kits that I keep in and around my lab, and I’ve even snagged a few of the original/old versions on eBay. Dave Miga is an incredible guy and designer… He’s also the original designer of the ESR tester known as the “Cap analyzer 88A”. It was designed decades ago and was the first in circuit ESR tester design on the market… It was so good that Even the big boys like BK precision and others copied his original design.
There are many Other low ohms/short detectors
-the “half-ohm” multimeter adapter… Available on tindie for about $15.
-the “shorty”
-“short sniffer”
-wavetek sf10
I could keep going as there are many that have been on the market or custom designed over the years.
There are also devices called “short-circuit killers“… They don’t just find the short but they overload it with current therefore destroying it and in most cases restoring the board back to working order. It’s kind of a weird approach but used pretty commonly in the cell phone repair and laptop motherboard repair business. If you haven’t seen them just look up “short killer“ on Google or UA-cam… It’s kind of a weird approach but it seems to work for a lot of folks.
The cutters have a flat bottom side while the top are tapered., thus will want to ride up on the insulation and slip off. The insultation is actually being cut on a bevel as well when held right way up. When held upside down the bevel cut is on the insulation that stays and the flat cut is on the piece you want to remove.
Awesome Collab Masters. Tanks for share!
Stripping using the sidecutters backwards is something I was taught as an apprentice in 1976 - still do it to this day - don't even own a pair of wire strippers
Great little project! ... a suggestion for another project is another type of probe I found really usefull when I started out (and still use it sometimes) ... is a simple audio probe for signal tracing. To go with it you could also build a tiny battery powered amplifier from e.g. a TDA2822 (only a handfull of cheap parts) or similar and add a tiny speaker for use with the audio probe. This gives a very useful tool and also an introduction to amplifier building for e.g. headphone amps ... :)
Hi M8,
So if i understand you its audible signal tracer .
interesting i have seen something similar used in car repair but it was for hearing knocking and other irregularities on a car engine, via a stethoscope looking thing with a amplifier and a time scale reducer (took 1 sec and stretched the audio 10X(as normal sounds from the engine are are at 1k-5k rpm. this made it possible to hear scratching and other irregularities.
OK don't with the rant .
So hmm. if we do the same for electronic signals we should have a specific sound/audio for different types of signals and if we slow it down (because we can't hear frequency over 6-20k hertz so a single over this would be in-audible ) but if slowed down we should even be able to hear ultrasound.
just an idea don't have a clue if it works :D
@@RetroUpgrade Hi Retro ... yes an audible probe (with in series capacitor for DC blocking in case you probe something you shouldn't by accident) housed in an old writing pen body for ease of holding. Usually used for audio equipment, you inject e.g. a sine wave signal into the circuit then trace that signal through the circuit with the audio probe listening through another amplifier. I have many oscilloscopes here but still use my little audio probe at times. I made a tiny battery powered 2watt amplifier from a TDA2822 and used a tiny old scrap car speaker (in it's pod housing and built the tiny 2822 circuit board & battery into this too) for the output so the probe and speaker are completely isolated & hand held. It's a good alternative to an oscilloscope sometimes. You've got some interesting ideas on a variation ... :)
@@johnnybravo505 This is something I have in mind to do. I demonstrated a kinda ghetto version of that already just using PC speakers and a capacitor - I also used the same device to test if a motherboard or GPU is accessing the BIOS
ua-cam.com/video/2pAp1R24XyY/v-deo.html
ua-cam.com/video/0hWnkRl3t1Y/v-deo.html
@@LearnElectronicsRepair Yeah I thought it would fit in well with the kind of simple & cheap but useful tools your making regularly, especially if you can make it really small and handheld (I think you've already covered a small sig gen) and the same circuit with a couple of changes doubles as a perfect headphone amp circuit (and sounds great if you power it from a 9v battery). I used an old car speaker backseat parcel shelf "pod" from the 1970's that I found in my workshop when I moved in for speaker and housing (just didn't want to throw it out) but any small speaker could be used to make it a lot smaller. I look forward to your spin on it & you could get your mate Retro to design & print a housing .... :)
I found your channel through Hackaday where the tester video link was posted so its no suprise there are a lot of views. I do like how this project has evolved and I will be making one of these and powering it with Lipo batterys recoverd from disposable vapes.
Keep the videos coming please :)
Thanks and Welcome aboard. Have a look at the LER discord server, you may like it
Learn Electronics Repair is now on Discord! Come and join the fun, it's free.
discord.gg/vam6YC8vwU
@@LearnElectronicsRepair been following you for a few months and you are in my Discord 👍
Just ordered some of these, I had a look at the option to have them do the assembly out of curiosity (I'm a beginner and won't learn much by getting someone else to assemble it) and it was £30 so definitely not worth it for a project like this at least, maybe for larger projects it could be more viable.
I had an idea while watching this that might make for an interesting series but I'm not sure how possible it would be. I was thinking of all of the basic equipment needed to start in electronics repair as a hobby, and a lot of them have DIY solutions of varying usefulness floating around on here and I'm sure elsewhere. It would be brilliant to have a beginners course of sorts where you could walk the newbie through building some of their own equipment while introducing and expanding on some basic concepts in real world, useful (and potentially money saving?) examples.
Sounds like a lot of work but food for thought I reckon.
Thanks guys for an interesting video.
As a former calibration & measurement technician I find it very easy to modify this circuit even further - to a DeLuxe version meeting precision specs for an accurate plug-on milli-ohm meter device to your medium hobby multimeter.
That's another story, as this circuit was purely made up for tracing shorts on PCB's.
Thumbs up 👍👍
Thanks a lot :)
if you point us in the right direction i can give it a go and modify the Circuit so it meats industri standard specs.
be aware that i don't have a formal electronics degree 😜 so be gentle with me 😆
CXensation - why not post it on Discord Sponsored projects section - we can get some free PCBs made and send to you, if you are OK to publish the project 🙂
@@LearnElectronicsRepair My arthritis in my hands disallow me extensive use of the mouse for circuit drawing.
But I will take a discussion on a precision circuit with Retro Upgrade.
@@RetroUpgrade First off - we need a "kelvin" switch not to introduce offset voltages here - like a good quality gold plated contact switch.
The switch must be a slide contact point type to be self cleaning.
Remember that the measurement current passes thru the switch ranges thus affecting the indicated voltage ...
The ranges should be 20-50-100 mA - because most multimeters already have a 10mA range for their lowest ohm range.
The range resistors should be E96 1% types and the values should be corrected for the LM117 bias current, as this always passes thru the DUT (device under test).
This is done using a calibration procedure where you measure the voltage over a precision resistor, and then modify the range resistors to get a correct reading.
1% 10ohm and 100ohm resistors leaded type should do.
The voltmeter must have an accuracy of at least 2% on the milli Volts scale.
... that should give you a milli ohm meter prescaler of some 2-3% accuracy, which is Hi5 for current sensing resistors 🙂
@@CXensation Thanks a lot will try to source the necessary parts to make a prototype
great upgrade looks pretty cool :) would love to see the revisit videos to all the ideas in these comments :) also fantastic news about the sponsorship from PCBWay :) great colab too hoping for more :)
The community thing is the way to grow. People are already picking it up on youtube. Give it a go with a split screen video with you and Carlos/Detlef on a project.
Sounds Like fun will see with richard what he thinks :D
Definitely
Sripping the wire works on the Lobster pot principal!! 😁
Many thanks. Another excellent video
The point of kelvin probe is to measure the voltage at the absolute last point of contact for an accurate reading, that's important if you want to read the actual resistance, for short finding that's not important, the important thing here is a better connection for current to flow, I found that a pointy tip is much better for that, IMO a thin multimeter probe with the current wire soldered 1 CM from the tip is a better, more accessible and convenient solution for short finding.
Inspired by your first video I built my own circuit with a toggle switch toggling between 100mA trimmed with a 10 turn pot (useful when I want to measure actual resistance), and an adjustable one using regular pot paired with a transistor that is able to get up to about 500mA out of the 317 regulator, using this high current added more resolution and made it easier to find shorts in a close range.
Mohamed Gharib That's good to see you were inspired by my original version - this is what all this is about IMHO. Your version sounds very useful. For whatever reason the version with the kelvin probe was the most stable and highest resolution (it worked on the 1mA range) but this could also be attributed to the use of batteries as a power source.
I have and idea in mind that may have the combined advantages of kelvin clips and sharper points, and is cheaper than kelvin probes - I will be testing that on an upcoming video
@@LearnElectronicsRepair sounds great, looking forward to it, your your videos are a great source of information for us learning electronics at home.
Hey Richard I just ordered the pcbs unpopulated. The reason they wanted the extra file is because I wanted to order the board with components populated.
Your prototypes are better built than my final projects ⚡💥🤬
Haha priceless 🤣
Excellent. Very nice. I think it would work very well without a constant power supply. If we have a 5V source and use instead of the current limiter a single resistor of 100 ohms for 50mA, 47 ohms for 100mA we will get the same results. The resistance we measure is small, below an ohm and then it does not affect the current so much and we will have almost a constant current source. For overvoltage protection, a silicon diode can be placed in parallel with the testers in direct conduction, which will limit the voltage applied to the circuit to 0.7V.
It would not work with just a resistor as the current through the short would vary too much depending on the short 'resistance' to trace it accurately. This tester relies on accurately measuring voltages down to 0.001mV - the resolution of my Aneng 8008 meter. Fortunately LM317 cost almost nothing, and are easy to find on scrap PCB to salvage.
As an aside this would not work with a bench PSU set to 50mA either as there are large output capacitors on bench PSU that dump a large instantaneous 'discharge' current spike into the device under test (that the PSU can not control/limit) every time you used your probe
This device does not need a diode or anything else to limit the output voltage to 0.7V. Just like your multi meter on diode mode does not need a voltage limiter even though they usually output 3.5V-4V with enough current to light an LED and we all happily use meter on diode mode to poke around GPUs
I proved this emphatically on this video with theoretical and practical demonstrations. This 5V device will NOT damage a GPU or CPU! I also proved a bench PSU at 50mA can not be used in this way and *will* blow components
ua-cam.com/video/XEbWyQgX_Mc/v-deo.html
Give that a watch then let me know if you still have any concerns regards the voltage used to test. 😉
Thanks for the reply. I'm totally agree with what you said. I saw the other clips related to measuring small resistances and short circuits and you are right. A voltage limitation would only be necessary if the short is measured in the case of circuits that consume very little current and have high resistance.
Diode voltage limitation has the disadvantage of consuming batteries if a battery-powered source is used.
Great and useful videos regarding short circuit finding:
ua-cam.com/video/0eixDdCpiO4/v-deo.html
ua-cam.com/video/P_2GGNr4q1s/v-deo.html
ua-cam.com/video/XEbWyQgX_Mc/v-deo.html
ua-cam.com/video/i8TudEfD2Ao/v-deo.html
ua-cam.com/video/kGM-Zmrr6tc/v-deo.html
ua-cam.com/video/NUgO7v4cbKs/v-deo.html
ua-cam.com/video/GCHM_svGO4Y/v-deo.html
@Max Mini I think YT may have auto deleted the links in your reply (or the whole reply). Sorry if that happened it's not me. I can see the reply in my feed but not here
copy/paste
Max Mini
Thanks for the reply. I'm totally agree with what you said. I saw the other clips related to measuring small resistances and short circuits and you are right. A voltage limitation would only be necessary if the short is measured in the case of circuits that consume very little current and have high resistance.
Diode voltage limitation has the disadvantage of consuming batteries if a battery-powered source is used.
Great and useful videos regarding short circuit finding:
ua-cam.com/video/0eixDdCpiO4/v-deo.html
ua-cam.com/video/P_2GGNr4q1s/v-deo.html
ua-cam.com/video/XEbWyQgX_Mc/v-deo.html
ua-cam.com/video/i8TudEfD2Ao/v-deo.html
ua-cam.com/video/kGM-Zmrr6tc/v-deo.html
ua-cam.com/video/NUgO7v4cbKs/v-deo.html
ua-cam.com/video/GCHM_svGO4Y/v-deo.html
Thank you. It must be an error so I will try to post the reply again. I'm totally agree with what you said. The usage of a constant current source will provide more stability, cancels out the unwanted effect of the power supply voltage variation, extend the range of measurement and also will give us the reading of the real value of the measured resistance knowing the exact current that is used during the measurement. A diode voltage limitation would be necessary only in rare cases of circuits with very low power consumption and high resistance, but it has the disadvantage of a high draining batteries if a battery-powered source is used.
Here are some other great and useful videos that I liked very much regarding the short circuit finding:
The Amazing $1 Short Finder Upgraded! Convert your multimeter to a 4 lead Kelvin Probe Short Tracer
ua-cam.com/video/0eixDdCpiO4/v-deo.html
Convert Your MULTIMETER into an accurate SHORT CIRCUIT TRACER Finder for less than $1 Build This DIY
ua-cam.com/video/P_2GGNr4q1s/v-deo.html
The $1 DIY SHORT CIRCUIT TRACER Part 2. Will a 5V short finder kill sensitive components CPU GPU?
ua-cam.com/video/XEbWyQgX_Mc/v-deo.html
How To Find Short Circuit VRM MosFET With An ESR Meter
ua-cam.com/video/i8TudEfD2Ao/v-deo.html
Learn Electronics Repair #13 Short Circuit Tracing Techniques (8800GT Part 5)
ua-cam.com/video/kGM-Zmrr6tc/v-deo.html
Learn Electronics Repair #15 - Short Circuit Tracing part 2 (8800GT)
ua-cam.com/video/NUgO7v4cbKs/v-deo.html
MicroOhm Meter Short Circuit Finder Review Comparison Vici VC480C+ vs YR2050 Milli Low Ohms Meter
ua-cam.com/video/GCHM_svGO4Y/v-deo.html
Hey guys - nice to see the project keeps evolving! Just one thought: 2 CR2032 instead of the bukly AA or AAA cells? We should get enough current out of those, and with 6V we have enough headroom even for slightly discharged ones. @Carlos: great housing!
Hi Detlef. And thank you for your generosity and helping us to move this on to the next step. Your work is most appreciated.
2x CR2032 would give more than enough voltage, but how long would they last if running on the 50mA range. I have no idea what the current capacity of those batteries is.
ua-cam.com/users/DetlefAmend
Hi Detlef :), thanks a lot i worked hard on it :D it's actually parametric so i can modify it quite easily . but then CR2032 sound like a great idea could probably make a hosing with just the front part of my design would be a lot smaller and faster to print - 4,5h is a little to much for most ppl :P
i'll do a draft model for the CR2032 and send it to you and richard for review :)
think even we can fit the CR2032 on the back of the PCB no battery compartment needed
Btw you have a new subscriber ;) , you do really interesting stuff
@@LearnElectronicsRepair Seams like the medium capacity is about 235-250mAh so you should get a solid 5 hours at 50mA
@@RetroUpgrade Sounds good enough to me 😁 That's what I find so good about this channel - lot's of knowledgeable and friendly guys giving their time and ideas.
@Learn Electronics Repair Is anyone else smelling a revisit video 😂😂😂😂
Thanks for all those very interesting videos! I recently retired from testing & repairing medical electronic equipment. I built the “Amazing $1 Short Finder” using construction techniques very similar to yours. I put it in a repurposed minibox (from a discarded medical gadget) and used a 5 VDC wall wart for power. Without going into a long sob-story; How well do you think the short finder will work on a +55 VDC rail short buried deep inside a Tektronix 465 ?
Thank for your information, isn't it the same when we using diode mode which is quite common in multi meter
The BoM posted on PCBWay does not contain the USB port, switches, and terminal block article numbers. As the PCB is designed to accommodate specific-sized components, would you mind sharing some article numbers for these mechanical components? Thank you very much in advance
I'm in the same boat did you have any luck?
@@badgerfool1980 No luck yet, will let you know if I have figured it out though.
30:41 - That will strip easier if you face your cutters the other way about (someone named Richard showed me that one.)
Great project! How about a small enclosure with chassis mount banana plugs spaced to match the standard multimeter jacks so it just plugs into the meter when needed. Power from a lithium battery (rechargeable for the deluxe model) as others have suggested. Pogo pins make really good custom probe tips and if sockets are used they can be replaced easily - I have used them to make custom leads for my HP 4328A and HP 4338A milliohmmeters. Regards, David.
used to do this years ago if I could not find the miliOhm meter.
1A 1mV 1mOhm, no maths involved as long as the circuit could take the 1A.
A very stable constant current power supply was a bonus.
As i was normally checking connector backshells to chassis via EMC gaskets, there was no problem with the 1A.
Hi, welcome to the channel. That sounds useful for making measurements. Of course in the case of the short finder we don't actually need to know the actual resistance value - just where the lowest reading is. Why not pop over to the sponsored projects section on LER discord - we have some sponsorship from PCBway to work on projects and gadgets relevant to electronics repair. Everyone welcome.
Learn Electronics Repair is now on Discord! Come and join the fun and let's fix stuff together, it's free and a nice place to be. discord.gg/vam6YC8vwU
Sponsored Projects discussion discord.com/channels/896427792751820842/976398185629093948
I think just using 2 AA batteries with near 100 ohm resistor should do the trick. I have taken very stable and distinctive readings with this setup that pin point to the shorted component.
What about using a 12 ohm resistor with the LM317 for a 100mA range (a tad more but close) ?
I ordered the USB version. The switches aren't in the BOM, so not sure what to get and the PCB is not the same as the one in this video. The one i ordered is too narrow to mount a usb port on.
Hi Richard - Just a thought about the battery's - Why did you not use a single sell £1 18650 5V power bank, then you would not need to keep buying AA's.
anyone know what usb and terminals are used in the video?
I just posted links to the USB connector and switches on Discord thanks to Detlef, the terminal blocks are (I believe) 5mm pitch PCB terminals
Heya nice vid colab
do u accept repairs if i would send a graphics card that does not work anymore
email me electronicanaria@outlook.com
Personally 4 wires is better, but I think the kelvin clips are not needed, just two wires down near the probe point for voltage sense is enough, try it.
Did you see the original version at the start of this video - that's how I made it. The kelvin version is more stable for whatever reason
@@LearnElectronicsRepair Well you use USED the kelvin clips, I personally do not thing you need them clips, just solder the current carrying wires close (1/2" is fine) to the probe points, still 4 wire, no alligator clips needed.
@@user-rs8zg8ey2b For sure both methods worked - it is possible the battery version is more sensitive/stable purely because of the fact batteries are more stable than USB or bench PSU rather than due to the use of the Kelvin probes.
I have an idea for a very inexpensive 'off the shelf' version of kelvin probe so when the parts arrive I will do a direct comparison between kelvin probe, attaching current wires to standard meter probes and my other idea on another video. Then we can all see what, if any, difference it makes 😉
@@LearnElectronicsRepair Great, will wait for the outcome, personally, the stubborn shorts I come across are on 20+ layer pcbs costing 3 to 5K, the DUT consumes up to 80A, I start with 100mA, but find I need to go higher on the current (even up to 2A), there is 2000+ decoupling caps on these boards.
Where would a curve tracer fit into this?
That's a different project, currently being worked on. Watch this space
Would this work on smd capacitors?
To find shorts on capacitors? Yes. In the original video I showed the tracer is able to find one shorted capacitor in a bank of SMD caps all adjacent to each other
ua-cam.com/video/P_2GGNr4q1s/v-deo.html
Thanks Richard!
How do I order as a project from pcb way ?
It should be available now on this link in this videos description - I'll check in the morning
Hey Mark, here is the link where you could quickly get Richard's pcbs: www.pcbway.com/project/shareproject/_1_Short_Tracer_USB_Version_by_Learn_Electronics_Repair_UA-cam_Channel_f3ce0bdc.html
LM317 draws 50uA Iadj.
can you help with my expensive laptop? I spilt wine on it and need help? message me if you can thanks
email me electronicanaria@outlook.com
since youre not measuring actual value but only difference lead drop dosnt really matter as long as it is consistent (iow. kelvin probes/attaching at test lead ends is pointless). thus better solution would be lcr plug in style addon or even hacking the mm and using its power source and internal space
Hi.
Is there som circuit inside the lcr probes that I am not aware off? If not is there a difference? Did a quick search for lcr probs and they range in price from 20-50€ for the cheap Ones and the cheap Kelvin probes cost in the range 3-15€ for the cheap ones. I am really curious. Am I missing something? (disclaimer I am a electronics noob)
I have another very low cost and less bulky option to the kelvin probes to try. It's still four lead though. I just have to wait for the stuff to arrive to try it
I just looked at PCBway, their way of searching project makes the site useless. there are over 40 pages of audio (most of them amps) and i never found anything that got my attention. Nice idea bad execution.
Why not get the real thing from the author who makes this since 1995?
Search for miron63, measures ESR, LCR too
Yes I got this one too, works wonders. Measures capacitance in 1 second on any size capacitor even 10000uf or larger. Hower it needs some work as the only thing made without problems is PCB. The case, connectors are cheap china crap. Price doubled on my after replacing these components.