When using linear regulators ALWAYS check the datasheet for the type you are using. Many regulators will be damaged if there is a high value capacitor on the output when the power is switched off. Check the regulator datasheet for reverse bias protection.
Linear voltage regulators are a type of voltage regulator that use a linear circuit to maintain a constant voltage output. This is in contrast to switching voltage regulators, such as buck converters, which use a pulse-width modulation (PWM) circuit. There are several key advantages of linear voltage regulators over switching voltage regulators: - They are simpler and more reliable than switching regulators. - They can provide a more stable output than switching regulators. - They can be used with higher input voltages than switching regulators. - They are less efficient than switching regulators, but this is not usually a problem for low-power applications.
When using components that require 5V only, the ripples from buck converters can be fatal. Here, the lm780X wins. It keeps the voltage very stable. Very informative video.
Buck converters always have a little bit of output ripple. If this is undesirable, you can use a buck converter to step down to just above the dropout for your linear regulator, then use the linear regulator, which won't need to drop as much voltage, generating less heat.
@Regina-mr4tb It would help, but even with lage value ones like 2200MF, you still can detect some ripple. I build detectors for spacial electromagnetic detection, and buck converters do not work because of the harmonics. The above comment is pretty good. I just have my DC unregulated output VERY close to my desired voltage to minimize losses.😊
Well-presented and well described! I needed a primer on this subject and you provided precisely what I needed to know, in a concise and easy-to-absorb manner. THANK YOU, and GOOD JOB!!
This was a very useful video; thank you! One thing I've been using linear regulators for is variable voltage but low amperage equipment, like solar chargers, etc.
I also did the same comparison and found the same problem with linear voltage regulator as it turns too hot to handle. Now i have an actual mobile charger inside my motorcycle compartment using a buck converter. It's so convenient as i can repeatedly charge my phone anytime, anywhere where there is no AC electrical outlet and I can do this even when not not using my motorcycle. It really draws less current than the linear one therefor less heating. I am using LM2576, by the way, but i'm not using heatsink ofr that matter. This video is a confirmation that I'm doing it right. Thank you for this video.
Thanks a lot for your comment! You are doing it right - a phone won't spot the difference between the "noisy" buck converter and "clean output" linear voltage regulator. The buck converter will definitely produce less heat and draw much less current.
ElectronFun.com By the way sir 18 years ago, i powered a two way CB radio with conventional power supply using step down transformer because back then i really don't know there are different ways to power different devices. All I know is that if i have a step down transformer, a full wave bridge type rectifier diode and a filter capacitor that's it i have a power supply. I really didn't know about buck converters until just two months ago. Your video helps a lot sir... Thank you
Recently I built an analog audio effects device and was intending on powering it with a 15Vdc walwart that used a switching power supply. Turned out it created an intense whine in the signal output. I switched to a linear supply and it worked better but had hum. No matter what size cap I added, it hummed. I added a linear voltage regulator that was set about 2.5 volts lower than the supply voltage and all noise was eliminated. There's a video on using linear regulators that explained why large caps are not needed on their outputs. That gave me the answer I was needing.
Excellent analysis overall. I'm a power designer, and I'd take a buck over a LDO any day. The LDO is best suited to minimal step down and power consumption applications. LDOs do have a size advantage, not requiring an inductor or possible external switch.
You are great. You provided a very practical explanation with a very clear view of use through good camera angles and an example of best use scenarios. THANK YOU so very much.
You can use a buck converter with RF type circuits you just have to cover it with a metal cover aka a Faraday Cage and then connect a ground wire from the cage to ground for the circuit ( attenuate the static field from the buck converter's coil) Great video 👍👍👍👍👍
I’m building a bench power supply which will have a linear regulator with a switching buck pre-regulator. This hybrid design is supposed to combine the advantages of each. Or compromise the disadvantages depending on how you looks at it. We’ll see how it works.
Thanks, I'm in the process of building some 3v3 output battery packs and needed to decide which type of regulator was best. Clearly a buck converter offers the best efficiency. Now I need to come up with a lean design for a small undervoltage cut off that doesn't bleed power from the batteries faster than the ESP01s I'll be powering. (something simple with a zener and a comparator, I'm hoping)
There is one more thing to mention: For circuits including A/D convertors (12 bit and more) the SMPS noise affects the accuracy of the ADC. To avoid this you should either use very expensive 4 layer PCB, or very lengthy software filters or both. In such applications the best thing to do is to use use SMPS + Linear Regulator combination. SMPS output should be held low, for example 6V and Linear Regulator should be "Low Dropout" type. such as LP5907.
ElectronFun.com Yes, it does. We are currently designing a energy analyzor in our company. At the beginning we were using a SMPS with 5V output to power the input microcontroller with 14 bit ADC inputs. We had a lot of problems concerning the accuracy of the ADC which we hadn't see in the breadboarding stage where 5V is obtained from transformer + LM7805. But when we started to use SMPS the problems had begun, especially if the inputs were low. We had to implement lots of lengthy software filters which slow down the measurement. Then we increased the output voltage of SMPS to 6 volts and started to use a low drop out 5 V regulator. Now we have a very nice circuit :) The reason is the noise reduction ability of the linear regulator, which is around 120dB
The previous calculations are OK, which indicate the input power, separately. "Ploss = (Vin-Vout) x Iin" is only suitable for linear voltage regulator, not for buck converter. The power loss of buck converter could be estimated theoretically only if we known about the main switch and diode parameters. Furthermore, the process is quite complicated. The most convenient way to calculate power loss precisely of buck converter is to measure the input power, as well as output power, and use input power minus output power to figure out power loss.
Has anyone here tested the linearity of the buck converters vs the "linear" voltage regulator, under a variety of loads? A square-wave signal generator, for example, would be a very interesting test of a linear psu. Cheers
I have no idea about Pakistani electronics market, sorry. Do you have access to eBay, Amazon, AliExpress or Banggood? You should be able to buy these items there.
I fixed that problem using a stepped secondary transformer. For example, if I need 5 volts output I use 7 volts input, if I need 9 I use 11 volts input and so on. Then (7V - 5V) x 0.42A = 0.84 W. Just need do some math to calculate a proper stepped secondary voltage. I am using this trick on my LM317 variable power supply .
Great video! I did have a question about your math. Wouldn't it be the power dissipated across the buck converter in the calculation? Input: 12V x 0.21A = 2.52W Output: 5V x 0.45A = 2.25W Thus the power dissipated across the buck converter would be 0.27W. Buck converter efficiency is about 92% and that calculation above would show ~90% efficiency.
you can use metal shielding around the buck converter i think you can buy them with metal shields already presoldered to the PCB if you are building a sensitive electronics
I have noticed that some of the E-Bay buck converters don' actually regulate the output voltage, they just "step it down", so when your battery supply drops, even a little, so does the regulator output. I suppose it serves me right for thinking that a .99 switching converter would be just as good as the outstanding, Murata "7805" replacements which cost more than four dollars.
There are so many low quality parts all over the Internet, it's not only about eBay. Some say that you get what you pay for, which may be true in many cases, but not always.
This is a HUGE help for me. I am trying to put an F.M radio inside a 1950s radio cabinet. I bought a kit, but it didn't have a good tuner that would fit in the existing spot, so I bought another kit that has a digital readout for the tuner. The first kit runs on 12 VDC, the second on 3VDC, so I was looking for a way to drop the voltage on only one part of the circuit. I'm not very adept at electronic theory so , I'm kind of stumbling in the dark as far as what I want to do and how to do it without ruining things. I had intended to use an old cell phone charger to power the unit. It's a 12 volt charger, but I don't know what amperage the two kits require, so I'm unsure if this is a safe way to decrease the power going into the unit and then how to decrease it again for the digital readout. Any pointers you can offer are deeply appreciated. Thanks.
When we caclulate efficiency of the voltage regulator we have to compute power loss. It's easy to calculate for linear regulator (just as you did - current multiplied by voltage difference). But for buck converters you have to calculate it like: Iin * Uin - Iout * Uout, where Iin - input current, Uout - output voltage etc.) For nonlinear converters input current != output current, that's their "magic".
Fantastic thanks wish a genious like you (I am quite serious) could make a little something that'd help us by explaining how these two different components work!
There are many different types of voltage regulators available on the market, each with its own set of pros and cons. In this article, we'll compare two popular types: buck converters and linear voltage regulators. Buck converters are a type of switching regulator that convert DC input voltage to a lower DC output voltage. They are smaller, lighter, and more efficient than linear voltage regulators, making them a popular choice for portable devices. However, they can be more complicated to use and may not be suitable for all applications. Linear voltage regulators are simple and reliable, but they are less efficient than buck converters and can take up more space. They are a good choice for applications that require a stable output voltage or where low noise is important.
About your computer power supply note: Technically, all switch-mode power supplies that don't have a voltage doubler are buck converters. They take rectified 120v or 240v AC in and have switchers that drop it to the several voltages needed for your computer. The only difference is they convert AC to DC before the switcher gets it's turn to work.
Now, to add some thing (although this is a quite old video): Fun fact: buck/boost converters can be much less efficient than a LDO on either very low loads or very high loads (often under 50%). So thats a drawback too. And: you measured the temperature of the coil, not the IC itself: now that may be important for a higher load to also measure the coils temperature, but thats atleast a 1-2A rated coil. The most heat will be generated through the mosfet in the buck IC
When you want a stable voltage with a low current in a small device then there are tons of smaller Voltage-Regulators to chose. Especially when you use a battery the oscillator and minimum load of the buck-switching supply will waste more power than the classical regulator-ic. Switching supplies also have a bigger ripple and that is why high-precision laboratory psus combine both technologies. The output of the switcher is later flattened with a "classic" regulator that is transforming the excess power into heat.
That's true - everything depends on your particular application. Sometimes a buck converter will work a lot better, but in other circuits it will perform much worse than a linear voltage regulator.
A resistor is used to reduce current flow rather than voltage. There are some other applications too. For example, you could build a voltage divider out of resistors and get your desired voltage level, but you would have to assume constant source voltage. What's more, the efficiency of such contraptions is far from perfect.
Hi ElectonFun thanks for your reply. So would you say a resistors best use would be to reduce small amounts of current say for a 3v LED with a power source 6v? I have project with a power source of 12v. But most of my components are 5v to 3v. would than a buck converter be a good choice for stepping down the voltage?
Resistors are often used to reduce current drawn by LEDs to protect them from burning out. I don't know what your project is, but a buck converter should be a good idea for most projects.
codoyen - Resistance voltage dividers are used almost everywhere when noise matters. Look at some schematics. Recent developments in LDO technology is something you should look into before touching junk, mass produced Chinese buck/boost converters.
+Shovel dam dude... XD LoL that is totally different.. Buck converter & LM > Regulating voltage / supplying steady voltage to circuit. (ideally didn't consume power. just passing it by. Just like non-linear component ) Resistor > Consume power. Dissipating power into heat. If you add device to the circuit after resistor, it will then divide the voltage output, which will then cannot supplying steady 5Vdc on the output side. ;-)
great info... I can see many vidoes to great emergency power banks using 7805IC. No one discussed about temperature. Please let us know if it's good idea to build emergence power banks using 7085IC or not and how efficient it would be. Thanks
Could you post a link to one of these videos? The LM7805 is not the best choice for a power bank. There are battery charging circuits ready to use on eBay, which can even handle cell balancing. They are fairly cheap - the prices start at around $2.
Efficiency depends on voltage drop. Buck converters always need 2V to function. Whereas linear regulators can have very low drop out voltage. If the input voltage matches the drop out voltage then the efficiency can be higher on linear than buck. For example, Linear Tech's LT3014 has a drop out of 0.35V. So if the input is 80V and the output is 79.65V for an LED string, the efficiency is 99.6%, i.e. near perfect. If you is a buck then you'd have to lose an LED, so output voltage is then about 76V and efficiency goes down to 95%. For higher currents buck converters are also quite expensive and gets bigger. Noise, both audible and electrical is also an issue in many application from medical, radio, power to audio etc.
+Thanh Tran Thanks for your comment. You are mentioning very specific conditions and the LT3014 can deliver only 20mA. Any buck converter is much noisier, but at the same time much more versatile.
ElectronFun.com I think both have their places. Also the comparison was not quite fair in your video. When selecting a topology one would look at it carefully and check the current versus the rating of the component. I would not leave the regulator running without a heat sink knowing that it would have to dissipate 2W. If you being fair you would use the linear regulator as a voltage reference to drive a power MOSFET. Then you realise that for a lower cost, you can get higher switching current on a linear regulator circuit than a buck circuit. That is why if given the choice i would prefer a bench power supply with linear regulator than a bench switching power supply. There is no point having a good bench power supply if the voltage is not stable enough.
+Thanh Tran I agree - there is enough room for linear voltage regulators and buck converters. I'm not sure why my video is unfair - I said voltage regulators radiate heat and are pretty inefficient, but they don't cause noise, while buck converters are efficient but pretty noisy.
ElectronFun.com the unfair part, in my humble opinion is that when selecting between two components for a design one would weight the pros and cons carefully. Checking the spec sheet I know would that the linear regulator is not suitable without a heat sink so if you have a space constraint then I would discard that option. However, knowing that it has to dissipate that much heat and there is space then I would put on a heat sink so it will still work. Efficiency is not always that critical. So to be "fair" to either choices they have to be both considered and designed, not just selected because they can both in theory perform similar task.
+Thanh Tran Sure, efficiency is not always the most important aspect - I agree. I tried to be as fair as I could, but probably wasn't trying hard enough. I always appreciate people who can justify their opinions. Thank you for your constructive criticism - it helps me make better videos.
The lm78xx range should never be used without a heatsink, but will produce a output with much less ripple than the buck converter. In some instances a zener diode based regulator would be a better choice.
What about reliability? The biggest dilemma I've run into is how to rate reliability because the switching regulator uses so many more components that can fail. But the linear regulator can also burn out if over temp, no? Please comment on this topic.
It's not an easy question. Linear voltage regulators are quite reliable - they usually don't burn out easily, because they shut down if they get too hot. On the other hand when you buy a decent buck converter it should serve you well too. The cheapest ones may fail at times, especially if you run high currents through them.
Testing reliability is not easy and would require many items of the same type to check how many of them fail. My channel is way too small for such experiments - I simply don't have resources to do that.
Ive seen the output of a linear voltage regulator on a oscilloscope before, but not of a buck/boost converter. Does the buck/boost converter put out a clean dc voltage? If not, would some capacitors clean it up?
I have a couple of those buck converters (the one shown at 2:19) however, I'm going to build my own switch mode power supply from scratch in the near future, I already have a "draft" schematic in my head. Linear regulators are still convenient and useful for small loads though.
+ElectronFun.com Of course. That's going to be a few projects from now, I still have a few other projects and various experiments that I want to get done.
Here is a question that seems problematic for most people to answer. I currently have auxiliary LED light on my car that have both full light and parking light feature. There are three cables 12v feed for full light, 12v feed for parking light and ground. The parking LED lights are too bright and I need to dim them. As it is in my car, the space is minimal. I would like to lower the light output by lowering the voltage feed to the parking LED with 9V, however this can only be done on the 12V feed wire, meaning I can´t use the negative wire as the negative wire is the same for both the parking LED and the full LED light. Can I use a buck converter and only take the output + feed from it and connect it to the parking light feed wire so it will only feed 9V? or do I have to connect both + feed and - feed from the converter to get 9V feed to the LED?
i have found the buck converter you used to be very sensitive to temperature- take it outside in the winter after a few minutes the output voltage drops . Take it back into the house the output rises, hold it in my warm hand- voltage rises even more- even worse put it into an unventilated small enclosure ...output keeps rising. Do you know of a more temperature stable adjustable output Buck converter?
U can use ic 7805 for small circuits drawing low amps like usb micro sd fm module...but not hard drive ...and also mainly up to 12volts ...ic7805 can power small circuits well ...it's also cost cutting very cheap..you are right not good for heavy circuts like hard drive...
Great video. One sidenote though: at this moment you can buy 10pcs of the same buck converter for $4 on aliexpress. Takes a lot of time to get it, but 40c is not a bad price.
It should work just fine. However, I've seen some comments saying that there are buck converters on the market, which are not able to cope with changing input voltage. I've never seen such a buck converter myself, but who knows. As you mentioned - the prices are so low, that you may come across a really poor quality devices.
Too much information in a very short video. Loved it .Please give the link where I can buy those converter. Where did you get that small green one BUCK converter.
Thanks a lot :) Would you prefer longer videos? I bought all 3 buck converters on eBay. You can buy the small one here: www.ebay.com/sch/sis.html?_nkw=1x+Mini-360+DC%2FDC+Buck+Converter+Step+Down+Module+17x11x3.8m+4.75V-23V+to+1V-17V&_id=291247572887&&_trksid=p2057872.m2749.l2658.
8 років тому
You can now buy some very very cheap buck converters for about 0.80$ out on eBay, bought some recently and they do the work!
Hi, theoretically you could, but in most cases the results would be difficult to predict. Even though 2 regulators of the same kind look identical, their specs may vary slightly. These differences will lead to one regulator being utilized more heavily than the second one. It is not a good practice. However, there are voltage regulators designed to work in parallel, but they used to be quite expensive.
Hey, I think, you should measure the temperature again on the actual chip of the buck converter since you measured on the inductive output load. Thanks for the video anyways :)
Good video. I have a question related to this. How do I conect the out puts from two 5v/2.4a usbA ports, each is connected to separate power source, in this case, two separate 21w solar panels, to get one 10v output? I tried to do so using two different, typical 5v/2.1a usb wall chargers, but could not double the voltage. My goal is to input the power from two separate backpacker style solar panels into one femsle usbc terminal. Currently, ( no pun intended) I am using a cord thst has 5pin push in with screw terminals on one end and a female usbc on the other. I was not able to draw any greater amperage or voltage or wattage by combining the usbA output leads in the same screw blocks. I tried both +to+ and +to- in the screw terminals.. I wonder if inputing one set of leads to the D+&D- would transfer the wattage from the second solar panel to the usbc output terminal? {The cables I used before were usba power only . From there I will connect a QC2.0/3.0usbc/ PD(?) Usbc male input(&output?) with dual output consisting of one usbc output (&input?) amd one usba output only. From there I hope to charge a 30w input (i have already input 37 watts at 19v ) 45w output 20,100 power bank. Tyia for any good feedback.
What if i use a buck converter to get close to 5v, then use a linear voltage regulator to clean up the voltage? Would that be effective? Would it still be a waste? Edit: just found my answer as a suggestion below, thanks!
Well done sir an excellent presentation, I would like your input on a project. How can i drop 60 volts DC to 12 volts, can you recommend a buck converter that can work.
A 7805 need a heatsink if you need to use it near max current rating. Comparing the cost of a single 7805 vs a module is not fair. You should compare it to the part on the module.
what if input volate is not constant it may varry from 7 to 15 volates as battery get too charged or discharged and we need constant fixed 5v output. which option will be suitable?
firstly , thanks for your informative video , secondly , i want to know which one is better for my radio controller (im changing my battery to lipo and need to regulate the output voltage ) to have a consistent and steady output that at the same time wouldn't interfere with my radio frequency.
+Ali Jazani Thanks for your comment. Buck converters are efficient, but they are much nosier than linear voltage regulators. If you don't want to experiment too much, I guess your should choose a linear voltage regulator. A buck converter might interfere with your radio frequency.
When using linear regulators ALWAYS check the datasheet for the type you are using. Many regulators will be damaged if there is a high value capacitor on the output when the power is switched off. Check the regulator datasheet for reverse bias protection.
Linear voltage regulators are a type of voltage regulator that use a linear circuit to maintain a constant voltage output. This is in contrast to switching voltage regulators, such as buck converters, which use a pulse-width modulation (PWM) circuit.
There are several key advantages of linear voltage regulators over switching voltage regulators:
- They are simpler and more reliable than switching regulators.
- They can provide a more stable output than switching regulators.
- They can be used with higher input voltages than switching regulators.
- They are less efficient than switching regulators, but this is not usually a problem for low-power applications.
In such case you have to add a feedback diode on its input and output reversed bias and you're good to go
@@drinkintea1572it's called freewheel diode🤔
@@aplacetoimproveteslacoilin3721 bro using chatgpt
When using components that require 5V only, the ripples from buck converters can be fatal. Here, the lm780X wins. It keeps the voltage very stable. Very informative video.
Thanks for this. I waz wondering why voltage regulators were used on things like arduino instead of a buck converter
No wonder my phone battery plays up on my powerbank
Buck converters always have a little bit of output ripple. If this is undesirable, you can use a buck converter to step down to just above the dropout for your linear regulator, then use the linear regulator, which won't need to drop as much voltage, generating less heat.
E se usar capacitores maior não resolveria?
@Regina-mr4tb It would help, but even with lage value ones like 2200MF, you still can detect some ripple. I build detectors for spacial electromagnetic detection, and buck converters do not work because of the harmonics. The above comment is pretty good. I just have my DC unregulated output VERY close to my desired voltage to minimize losses.😊
Well-presented and well described! I needed a primer on this subject and you provided precisely what I needed to know, in a concise and easy-to-absorb manner. THANK YOU, and GOOD JOB!!
Dogmakarma Store Thanks a lot!
This was a very useful video; thank you! One thing I've been using linear regulators for is variable voltage but low amperage equipment, like solar chargers, etc.
most useful thing i’ve seen all day, you gave me another reason to scour my spare/crap psu’s for recoverable components.
I also did the same comparison and found the same problem with linear voltage regulator as it turns too hot to handle. Now i have an actual mobile charger inside my motorcycle compartment using a buck converter. It's so convenient as i can repeatedly charge my phone anytime, anywhere where there is no AC electrical outlet and I can do this even when not not using my motorcycle. It really draws less current than the linear one therefor less heating. I am using LM2576, by the way, but i'm not using heatsink ofr that matter. This video is a confirmation that I'm doing it right. Thank you for this video.
Thanks a lot for your comment! You are doing it right - a phone won't spot the difference between the "noisy" buck converter and "clean output" linear voltage regulator. The buck converter will definitely produce less heat and draw much less current.
ElectronFun.com By the way sir 18 years ago, i powered a two way CB radio with conventional power supply using step down transformer because back then i really don't know there are different ways to power different devices. All I know is that if i have a step down transformer, a full wave bridge type rectifier diode and a filter capacitor that's it i have a power supply. I really didn't know about buck converters until just two months ago.
Your video helps a lot sir... Thank you
I knew buck converters were more efficient, but I didn't know just how much. Thank you for the explanation.
Thank you.
I learnt something new today.
That's great! Thank you for your comment :)
Recently I built an analog audio effects device and was intending on powering it with a 15Vdc walwart that used a switching power supply. Turned out it created an intense whine in the signal output. I switched to a linear supply and it worked better but had hum. No matter what size cap I added, it hummed. I added a linear voltage regulator that was set about 2.5 volts lower than the supply voltage and all noise was eliminated. There's a video on using linear regulators that explained why large caps are not needed on their outputs. That gave me the answer I was needing.
Is it better to use a buck converter or linear voltage regulator in you project? ua-cam.com/video/giGRrODKJSE/v-deo.html
Good video with your clear voice and without unbearable playback music.
Excellent analysis overall. I'm a power designer, and I'd take a buck over a LDO any day. The LDO is best suited to minimal step down and power consumption applications. LDOs do have a size advantage, not requiring an inductor or possible external switch.
You are great. You provided a very practical explanation with a very clear view of use through good camera angles and an example of best use scenarios. THANK YOU so very much.
You can use a buck converter with RF type circuits you just have to cover it with a metal cover aka a Faraday Cage and then connect a ground wire from the cage to ground for the circuit ( attenuate the static field from the buck converter's coil)
Great video 👍👍👍👍👍
Все ясно и по делу! Спасибо!
I’m building a bench power supply which will have a linear regulator with a switching buck pre-regulator. This hybrid design is supposed to combine the advantages of each. Or compromise the disadvantages depending on how you looks at it. We’ll see how it works.
Thanks, I'm in the process of building some 3v3 output battery packs and needed to decide which type of regulator was best. Clearly a buck converter offers the best efficiency. Now I need to come up with a lean design for a small undervoltage cut off that doesn't bleed power from the batteries faster than the ESP01s I'll be powering. (something simple with a zener and a comparator, I'm hoping)
There is one more thing to mention: For circuits including A/D convertors (12 bit and more) the SMPS noise affects the accuracy of the ADC. To avoid this you should either use very expensive 4 layer PCB, or very lengthy software filters or both. In such applications the best thing to do is to use use SMPS + Linear Regulator combination. SMPS output should be held low, for example 6V and Linear Regulator should be "Low Dropout" type. such as LP5907.
oilbay54 Thanks a lot for your useful comment! I didn't know buck converters may affect the accuracy of analog to digital converters.
ElectronFun.com Yes, it does. We are currently designing a energy analyzor in our company. At the beginning we were using a SMPS with 5V output to power the input microcontroller with 14 bit ADC inputs. We had a lot of problems concerning the accuracy of the ADC which we hadn't see in the breadboarding stage where 5V is obtained from transformer + LM7805. But when we started to use SMPS the problems had begun, especially if the inputs were low. We had to implement lots of lengthy software filters which slow down the measurement. Then we increased the output voltage of SMPS to 6 volts and started to use a low drop out 5 V regulator. Now we have a very nice circuit :) The reason is the noise reduction ability of the linear regulator, which is around 120dB
Both buck converters and linear voltage regulators are improved by adding 100nF ceramic capacitor across the output.
The previous calculations are OK, which indicate the input power, separately.
"Ploss = (Vin-Vout) x Iin" is only suitable for linear voltage regulator, not for buck converter.
The power loss of buck converter could be estimated theoretically only if we known about the main switch and diode parameters. Furthermore, the process is quite complicated.
The most convenient way to calculate power loss precisely of buck converter is to measure the input power, as well as output power, and use input power minus output power to figure out power loss.
I was measuring current draw on the input, which gave me power consumption of my dummy load + buck converter/linear voltage regulator.
Has anyone here tested the linearity of the buck converters vs the "linear" voltage regulator, under a variety of loads? A square-wave signal generator, for example, would be a very interesting test of a linear psu. Cheers
I haven't tested that, but I agree it could be a nice experiment. Maybe someone else has already done that. Anyone guys?
Very nice lesson, thanks master. Clear and concise.
+Hernan Ortiz Thanks a lot :)
wow grate thank u dear i love u...
Thank you for your comment and kind words 😃
please can you tel me how can i purchaze it in pakistan?
I have no idea about Pakistani electronics market, sorry. Do you have access to eBay, Amazon, AliExpress or Banggood? You should be able to buy these items there.
Mr Engineer bro you can buy it from hall road lahore..
@@Mrengineer1 why are u gay
I fixed that problem using a stepped secondary transformer. For example, if I need 5 volts output I use 7 volts input, if I need 9 I use 11 volts input and so on. Then (7V - 5V) x 0.42A = 0.84 W. Just need do some math to calculate a proper stepped secondary voltage. I am using this trick on my LM317 variable power supply .
Wow what an invention... explain very easy way sir... thanks 👍
Very handy and well explained. Great comparison. Cheers
Thank you so much! Cheers :)
Great video! I did have a question about your math. Wouldn't it be the power dissipated across the buck converter in the calculation?
Input: 12V x 0.21A = 2.52W
Output: 5V x 0.45A = 2.25W
Thus the power dissipated across the buck converter would be 0.27W.
Buck converter efficiency is about 92% and that calculation above would show ~90% efficiency.
you can use metal shielding around the buck converter i think you can buy them with metal shields already presoldered to the PCB if you are building a sensitive electronics
Sure, it's an option if you have issues with radio-frequency interference.
I have noticed that some of the E-Bay buck converters don' actually regulate the output voltage, they just "step it down", so when your battery supply drops, even a little, so does the regulator output. I suppose it serves me right for thinking that a .99 switching converter would be just as good as the outstanding, Murata "7805" replacements which cost more than four dollars.
There are so many low quality parts all over the Internet, it's not only about eBay. Some say that you get what you pay for, which may be true in many cases, but not always.
This is a HUGE help for me. I am trying to put an F.M radio inside a 1950s radio cabinet. I bought a kit, but it didn't have a good tuner that would fit in the existing spot, so I bought another kit that has a digital readout for the tuner. The first kit runs on 12 VDC, the second on 3VDC, so I was looking for a way to drop the voltage on only one part of the circuit. I'm not very adept at electronic theory so , I'm kind of stumbling in the dark as far as what I want to do and how to do it without ruining things. I had intended to use an old cell phone charger to power the unit. It's a 12 volt charger, but I don't know what amperage the two kits require, so I'm unsure if this is a safe way to decrease the power going into the unit and then how to decrease it again for the digital readout. Any pointers you can offer are deeply appreciated. Thanks.
When we caclulate efficiency of the voltage regulator we have to compute power loss. It's easy to calculate for linear regulator (just as you did - current multiplied by voltage difference). But for buck converters you have to calculate it like: Iin * Uin - Iout * Uout, where Iin - input current, Uout - output voltage etc.) For nonlinear converters input current != output current, that's their "magic".
Fantastic thanks wish a genious like you (I am quite serious) could make a little something that'd help us by explaining how these two different components work!
There are many different types of voltage regulators available on the market, each with its own set of pros and cons. In this article, we'll compare two popular types: buck converters and linear voltage regulators.
Buck converters are a type of switching regulator that convert DC input voltage to a lower DC output voltage. They are smaller, lighter, and more efficient than linear voltage regulators, making them a popular choice for portable devices. However, they can be more complicated to use and may not be suitable for all applications.
Linear voltage regulators are simple and reliable, but they are less efficient than buck converters and can take up more space. They are a good choice for applications that require a stable output voltage or where low noise is important.
very useful video,Thank you so much
+Nick Mukbaniani
Thanks a lot! :) Sorry, I couldn't reply sooner - I was on vacation.
Excellent comparison.
Thank you very much :)
About your computer power supply note: Technically, all switch-mode power supplies that don't have a voltage doubler are buck converters. They take rectified 120v or 240v AC in and have switchers that drop it to the several voltages needed for your computer. The only difference is they convert AC to DC before the switcher gets it's turn to work.
Great explanation! I'll try to use one of this to replace the ramps 1.4 mosfet that feed my 3D Printer heated bed.
Thank you very much! I would leave the heated bed MOSFET. For this application it should be better than a buck converter.
Priceless educational video. Thumbs and legs up!
Giulio Buccini Such comments give me great motivation. Thanks a lot Giulio!
Now, to add some thing (although this is a quite old video):
Fun fact: buck/boost converters can be much less efficient than a LDO on either very low loads or very high loads (often under 50%). So thats a drawback too.
And: you measured the temperature of the coil, not the IC itself: now that may be important for a higher load to also measure the coils temperature, but thats atleast a 1-2A rated coil. The most heat will be generated through the mosfet in the buck IC
It is true that low-dropout regulators can be more efficient, but only in some specific conditions.
In my video the coil was a lot hotter than the IC.
ElectronFun.com well, those specific conditions would be when you want to drop only a small voltage :D like 5V->3.3V.
Fair enough :)
Well done, good job, thank you for your time.
Thank you for watching and your nice comment :)
When you want a stable voltage with a low current in a small device then there are tons of smaller Voltage-Regulators to chose. Especially when you use a battery the oscillator and minimum load of the buck-switching supply will waste more power than the classical regulator-ic. Switching supplies also have a bigger ripple and that is why high-precision laboratory psus combine both technologies. The output of the switcher is later flattened with a "classic" regulator that is transforming the excess power into heat.
That's true - everything depends on your particular application. Sometimes a buck converter will work a lot better, but in other circuits it will perform much worse than a linear voltage regulator.
good idea to heat coffee cup
You would have to use a bunch of LM7805s and a bucket of electricity ;)
Exactly what I was looking for.
thank you very much
Very clear and straightforward. Thank you!
Sound advise, professionally presented.
excellent presentation! very clear and objective!
+JR Eyes Thank you, thank you and thank you :)
Where would a resistor come in? I know a resistor can resist voltage too, but im guess they are not as efficient as buck converters?
A resistor is used to reduce current flow rather than voltage. There are some other applications too. For example, you could build a voltage divider out of resistors and get your desired voltage level, but you would have to assume constant source voltage. What's more, the efficiency of such contraptions is far from perfect.
Hi ElectonFun thanks for your reply.
So would you say a resistors best use would be to reduce small amounts of current say for a 3v LED with a power source 6v?
I have project with a power source of 12v. But most of my components are 5v to 3v. would than a buck converter be a good choice for stepping down the voltage?
Resistors are often used to reduce current drawn by LEDs to protect them from burning out. I don't know what your project is, but a buck converter should be a good idea for most projects.
codoyen - Resistance voltage dividers are used almost everywhere when noise matters. Look at some schematics.
Recent developments in LDO technology is something you should look into before touching junk, mass produced Chinese buck/boost converters.
+Shovel
dam dude... XD LoL
that is totally different..
Buck converter & LM > Regulating voltage / supplying steady voltage to circuit. (ideally didn't consume power. just passing it by. Just like non-linear component )
Resistor > Consume power. Dissipating power into heat. If you add device to the circuit after resistor, it will then divide the voltage output, which will then cannot supplying steady 5Vdc on the output side. ;-)
great info... I can see many vidoes to great emergency power banks using 7805IC. No one discussed about temperature. Please let us know if it's good idea to build emergence power banks using 7085IC or not and how efficient it would be. Thanks
Could you post a link to one of these videos? The LM7805 is not the best choice for a power bank. There are battery charging circuits ready to use on eBay, which can even handle cell balancing. They are fairly cheap - the prices start at around $2.
Excellent summary and explanation.
Thank you very much :)
Thank you for the Practical Video 🙏
Excellent video with no waffel.
Efficiency depends on voltage drop. Buck converters always need 2V to function. Whereas linear regulators can have very low drop out voltage. If the input voltage matches the drop out voltage then the efficiency can be higher on linear than buck. For example, Linear Tech's LT3014 has a drop out of 0.35V. So if the input is 80V and the output is 79.65V for an LED string, the efficiency is 99.6%, i.e. near perfect. If you is a buck then you'd have to lose an LED, so output voltage is then about 76V and efficiency goes down to 95%. For higher currents buck converters are also quite expensive and gets bigger. Noise, both audible and electrical is also an issue in many application from medical, radio, power to audio etc.
+Thanh Tran Thanks for your comment. You are mentioning very specific conditions and the LT3014 can deliver only 20mA. Any buck converter is much noisier, but at the same time much more versatile.
ElectronFun.com I think both have their places. Also the comparison was not quite fair in your video. When selecting a topology one would look at it carefully and check the current versus the rating of the component. I would not leave the regulator running without a heat sink knowing that it would have to dissipate 2W. If you being fair you would use the linear regulator as a voltage reference to drive a power MOSFET. Then you realise that for a lower cost, you can get higher switching current on a linear regulator circuit than a buck circuit.
That is why if given the choice i would prefer a bench power supply with linear regulator than a bench switching power supply. There is no point having a good bench power supply if the voltage is not stable enough.
+Thanh Tran I agree - there is enough room for linear voltage regulators and buck converters. I'm not sure why my video is unfair - I said voltage regulators radiate heat and are pretty inefficient, but they don't cause noise, while buck converters are efficient but pretty noisy.
ElectronFun.com the unfair part, in my humble opinion is that when selecting between two components for a design one would weight the pros and cons carefully. Checking the spec sheet I know would that the linear regulator is not suitable without a heat sink so if you have a space constraint then I would discard that option. However, knowing that it has to dissipate that much heat and there is space then I would put on a heat sink so it will still work. Efficiency is not always that critical. So to be "fair" to either choices they have to be both considered and designed, not just selected because they can both in theory perform similar task.
+Thanh Tran Sure, efficiency is not always the most important aspect - I agree. I tried to be as fair as I could, but probably wasn't trying hard enough. I always appreciate people who can justify their opinions. Thank you for your constructive criticism - it helps me make better videos.
Very interesting. So in a practical sense, would it make sense to use a buck converter to charge various devices from a car battery?
Thank you for a good presentation. Well done and very usefull
The lm78xx range should never be used without a heatsink, but will produce a output with much less ripple than the buck converter. In some instances a zener diode based regulator would be a better choice.
Great job breaking it down. Would you use the Buck for small audio amplifier application? Seems it is a lot less involved.
very nice explanation! you should make more videos.
This video is great educating and well explained
Thank you so much :)
Probably the most useful video ever suggested to me by UA-cam. Thanks a lot.
What about reliability? The biggest dilemma I've run into is how to rate reliability because the switching regulator uses so many more components that can fail. But the linear regulator can also burn out if over temp, no? Please comment on this topic.
It's not an easy question. Linear voltage regulators are quite reliable - they usually don't burn out easily, because they shut down if they get too hot. On the other hand when you buy a decent buck converter it should serve you well too. The cheapest ones may fail at times, especially if you run high currents through them.
Testing reliability is not easy and would require many items of the same type to check how many of them fail. My channel is way too small for such experiments - I simply don't have resources to do that.
Thanx for the great explanation. Very informative
Thank you for watching and your comment :)
Excellent, you have taught me something. Thanks.🇬🇧👍
Ive seen the output of a linear voltage regulator on a oscilloscope before, but not of a buck/boost converter. Does the buck/boost converter put out a clean dc voltage? If not, would some capacitors clean it up?
I have a couple of those buck converters (the one shown at 2:19) however, I'm going to build my own switch mode power supply from scratch in the near future, I already have a "draft" schematic in my head. Linear regulators are still convenient and useful for small loads though.
+CoolDudeClem A switched mode power supply built from scratch is a cool project. Are you going to make a video about it?
+ElectronFun.com Of course. That's going to be a few projects from now, I still have a few other projects and various experiments that I want to get done.
+CoolDudeClem Cool, let me know where to watch the videos when they're ready :)
+ElectronFun.com They're all on my UA-cam channel.
+CoolDudeClem I've just subscribed to your channel :)
Nice, high quality information.
Thanks a lot :)
What is the name of the buck converter you were using during the comparison?
Excellent, informative video. Thank you very much.
Here is a question that seems problematic for most people to answer. I currently have auxiliary LED light on my car that have both full light and parking light feature. There are three cables 12v feed for full light, 12v feed for parking light and ground. The parking LED lights are too bright and I need to dim them. As it is in my car, the space is minimal. I would like to lower the light output by lowering the voltage feed to the parking LED with 9V, however this can only be done on the 12V feed wire, meaning I can´t use the negative wire as the negative wire is the same for both the parking LED and the full LED light. Can I use a buck converter and only take the output + feed from it and connect it to the parking light feed wire so it will only feed 9V? or do I have to connect both + feed and - feed from the converter to get 9V feed to the LED?
i have found the buck converter you used to be very sensitive to temperature- take it outside in the winter after a few minutes the output voltage drops . Take it back into the house the output rises, hold it in my warm hand- voltage rises even more- even worse put it into an unventilated small enclosure ...output keeps rising. Do you know of a more temperature stable adjustable output Buck converter?
at 5:03 you said 0.42A at 12V, shouldn't that be 5V instead? Please correct me if I'm wrong. Nice demonstration btw!
I was measuring the input voltage and current consumption, that's why it's 12 and not 5V.
U can use ic 7805 for small circuits drawing low amps like usb micro sd fm module...but not hard drive ...and also mainly up to 12volts ...ic7805 can power small circuits well ...it's also cost cutting very cheap..you are right not good for heavy circuts like hard drive...
Great video. One sidenote though: at this moment you can buy 10pcs of the same buck converter for $4 on aliexpress. Takes a lot of time to get it, but 40c is not a bad price.
Thank you so much :)
I published this video 2 years ago and the prices indeed went down significantly.
I see... well another quick question: will the buck converter work fine with lipo battery which changes its voltage by time (as it is discharging)?
It should work just fine. However, I've seen some comments saying that there are buck converters on the market, which are not able to cope with changing input voltage. I've never seen such a buck converter myself, but who knows. As you mentioned - the prices are so low, that you may come across a really poor quality devices.
Very helpfull. Thanks now I can build my 5w laser
Also worth mentioning is that your buck converter is also only 30 cent on AliExpress
Too much information in a very short video. Loved it .Please give the link where I can buy those converter. Where did you get that small green one BUCK converter.
Thanks a lot :) Would you prefer longer videos?
I bought all 3 buck converters on eBay. You can buy the small one here: www.ebay.com/sch/sis.html?_nkw=1x+Mini-360+DC%2FDC+Buck+Converter+Step+Down+Module+17x11x3.8m+4.75V-23V+to+1V-17V&_id=291247572887&&_trksid=p2057872.m2749.l2658.
You can now buy some very very cheap buck converters for about 0.80$ out on eBay, bought some recently and they do the work!
Yes, they are pretty cheap sometimes.
Can I use multiple 7805 regulators in parallel to reduce heat for the same load. If so how should I place it.
Hi, theoretically you could, but in most cases the results would be difficult to predict. Even though 2 regulators of the same kind look identical, their specs may vary slightly. These differences will lead to one regulator being utilized more heavily than the second one. It is not a good practice. However, there are voltage regulators designed to work in parallel, but they used to be quite expensive.
I'll keep looking but I need 18V from a 6S LiPo Battery so I can use a camera gimbal with a UAS. Are there Buck converters for this application?
Hey, I think, you should measure the temperature again on the actual chip of the buck converter since you measured on the inductive output load. Thanks for the video anyways :)
Thank you for you comment. This may seem strange, but in my case the coil was hotter than the chip itself :)
Why do you need to use capacitors? I see others use the LM7805 without.
Read the data sheet, it will explain how to calculate heatsinks!
Good video. I have a question related to this. How do I conect the out puts from two 5v/2.4a usbA ports, each is connected to separate power source, in this case, two separate 21w solar panels, to get one 10v output? I tried to do so using two different, typical 5v/2.1a usb wall chargers, but could not double the voltage. My goal is to input the power from two separate backpacker style solar panels into one femsle usbc terminal. Currently, ( no pun intended) I am using a cord thst has 5pin push in with screw terminals on one end and a female usbc on the other. I was not able to draw any greater amperage or voltage or wattage by combining the usbA output leads in the same screw blocks. I tried both +to+ and +to- in the screw terminals.. I wonder if inputing one set of leads to the D+&D- would transfer the wattage from the second solar panel to the usbc output terminal? {The cables I used before were usba power only .
From there I will connect a QC2.0/3.0usbc/ PD(?) Usbc male input(&output?) with dual output consisting of one usbc output (&input?) amd one usba output only. From there I hope to charge a 30w input (i have already input 37 watts at 19v ) 45w output 20,100 power bank.
Tyia for any good feedback.
What if i use a buck converter to get close to 5v, then use a linear voltage regulator to clean up the voltage? Would that be effective? Would it still be a waste?
Edit: just found my answer as a suggestion below, thanks!
Well done sir an excellent presentation,
I would like your input on a project.
How can i drop 60 volts DC to 12 volts, can you recommend a buck converter that can work.
Awesome explanation!!
Thanks a lot 😀
Great job! Perfect video! I never seen anything like that in portuguese.
+Vinícius Aquino
Thank you so much! I don't know how, but I missed your comment.
Thanks Great video and for answering the comments. Very helpful..
No problem, thank you for the comment and your kind words :)
Thanks for that information. Very useful...!
A 7805 need a heatsink if you need to use it near max current rating.
Comparing the cost of a single 7805 vs a module is not fair. You should compare it to the part on the module.
Another great video, awesome, have a great day
Thanks a lot Daniel! Have a great day too :)
what if input volate is not constant it may varry from 7 to 15 volates as battery get too charged or discharged and we need constant fixed 5v output.
which option will be suitable?
Great presentation.
Nicely done, thank you!
Thank you!
@@ElectronFunCom
Which is best for motor driving
Another (best) option for electrical noise reduction, use an optio-isolater ic.
+Keith Jonas assuming your interfacing to a solid state circuit, and don't want electrical noise.
+Keith Jonas Good advice, thanks :)
awesome video... sir led ko drt ac par konse resistance ke sath lagau taki wo indicator ka kam karega
Thanks, but I don't understand most of the comment, sorry.
Awesome thank's for all yours video i juste discover you !!
Thank you :)
Thank you this was very educating.
firstly , thanks for your informative video ,
secondly , i want to know which one is better for my radio controller (im changing my battery to lipo and need to regulate the output voltage ) to have a consistent and steady output that at the same time wouldn't interfere with my radio frequency.
+Ali Jazani Thanks for your comment.
Buck converters are efficient, but they are much nosier than linear voltage regulators. If you don't want to experiment too much, I guess your should choose a linear voltage regulator. A buck converter might interfere with your radio frequency.
ElectronFun.com thanks again for your prompt reply . It was really helpful .
Great illustrative