Buck converter vs. linear voltage regulator - practical comparison
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- Опубликовано: 28 сен 2024
- In this video I'm comparing in practice a buck converter with LM7805 linear voltage regulator. Two driver boards from old hard drives are used as a dummy load to check efficiency and temperature of the buck converter and linear voltage regulator. I'm presenting pros and cons of both devices.
There are 2 mistakes in my calculations:
1. 5:02 - 5:08 - correct calculations should be: (12V - 5V) x 0.42A = 2.94W
2. 5:17 - 5:23 - correct calculations should be: (12V - 5V) x 0.22A = 1.54W
I double checked everything, but I should have triple checked. I'm sorry for my mistake.
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Video, edit, voice by Chris Lorkowski
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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.😊
wanted to know this for decades , very well explained and no stupid music , top man
YES! NO MUSIC!!!!!!!! Such a relief!!!!!
We were studying power supply last week and my professor never talk about buck converter. I wish my professor had your enthusiasm to explain thinks from A to Z like you did. Excellent video.
Thank you very much Edgardo :)
I never liked theory too much and always favor practical knowledge.
Or he is smart enough to understand that someone needs to learn to walk before learn to run, or maybe he understand that efficiency is not always the design priority, for example, in RF or audio circuits powered with sockets, getting a clean power supply without the dirty noise of buck converters is the priority.
It's so hilarious to see clueless millennials learning to power led strips thinking that they have "invented electronics".
Signed: the Boomer.
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 are perfect for smaller battery powered devices.
However, if in a heavier application, then use the flat pack ic/transistor with a sufficient heat sink.
Great video.
Is it better to use a buck converter or linear voltage regulator in you project? ruclips.net/video/giGRrODKJSE/видео.html
Great summary. I used to build circuits when I was a kid (early 90's), reading the circuit guides from Radio Shack, but fell out of it and got more into computers & communications. I find it's still a very useful skill to have, and I'm always trying to learn more and get back into it. Channels like yours are so valuable - if we had this kind of platform when I was a kid, who knows how many cool devices and ideas we'd have by now :)
Good video. Small addition: Don't go cheap on your power supplies. Would be like going keep on the foundation of a home. When cheap power supplies fail, they can do so catastrophically.
+Kent A. Vander Velden make your own one :)
Right on, with legit components :)
+Kent A. Vander Velden Thanks for your comment and advice. You're definitely right, it's not a good idea to use cheap buck converters for important projects.
so what is a recommended buck converter?
It is not as easy as one might think, but doable :)
Thanks for the informative video. Buck converters always sounded big, expensive and complicated for simple builds, but it's actually not that bad!
Thanks a lot for your comment. The prices went down significantly, so buck converters are not expensive at all right now.
use the waste heat from the linear voltage regulator to boil water for other uses.
If you wanted to boil just a single glass, it could work - who knows ;)
Yes. A tea cooker.
Hahahaha... 2 in 1 purpose. 1. For reducing voltage. 2. Boiler . (Heat generated from that linear enough to melt a plastics.
@@bhr987 if it doesnt go thermonuclear and pop before the temperature reaches plastic melting temps.
Nah you won't get enough heat for that lmao
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 use voltage regulators to heat my house.
how?
Nickel chromium
thats not possible ..
funny though
it is very good funny way to describe that voltage regulatörs produce too much waste heat while to adjust voltage :) . the irony
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
Linear regulator are not made to voltage conversion (ie, 12v to 5v), they are made to regulate voltage after a classical transformer and diode bridge rectifier. Additionally, buck converters (or conmutated power supplies) opperate at high frequencies and can cause interferences on RF or audio circuits. Each one has its pro and cons, you just need to choose the right one to your project.
Signed: The Boomer
Will it interfere with Bluetooth and wifi?
are you sure about that? because i was considering in use it in a microphone.
Clear, concise and very informative, all too often tuition videos are rendered unwatchable by totally inappropriate house music thumping out!....excellent, Thank you.
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!
most useful thing i’ve seen all day, you gave me another reason to scour my spare/crap psu’s for recoverable components.
Nice video, thank you! One thing though, the 7805's power consumption is (12v-5v)x.42 amp, but I get what you meant. It's a great comparison.
Thank you for your nice comment and letting me know about my mistake. I've just added annotations with corrected calculations. Sorry for my stupid mistake. I double checked everything, but I should have triple checked.
Your comment unfortunately is somewhat a rarity on RUclips. Pointing out an error in a civil professional manner. Thanks
waswestkan
Thanks a lot! I could correct the video and reupload it, but I decided to spend the time for preparing another video and let people know about my mistake. The only problem is - annotations don't work on mobile devices.
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.
Great explanation but just like to point out that you may not have incurred the failure of the VR had it been correctly setup with appropriate heat sink. This would also have improved its efficiency for your comparative data records I assume. I enjoyed the video :)
It wouldn't make any difference to efficiency. With a linear regulator, the source supplies the same amperage as the load draws from the output. With the buck regulator, the input current is much lower than what the load draws from the output. That's why it doesn't get hot. All the wattage gets passed from the source to the load. The buck converter probably dissipates less than 1/2 watt at the most.
Hello my friend,good day please can we use solar panel 12v to convert 7805 to get 5v to charge phone?
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 👍👍👍👍👍
This was hands-on and educational. ☺️ Thank you for this video uploader.
This video was the best I've seen so far for concisely describing and demonstrating the differences between the two, thanks so much for this.
Thank you.
I learnt something new today.
That's great! Thank you for your comment :)
I knew buck converters were more efficient, but I didn't know just how much. Thank you for the explanation.
I just visited this video after a year , and it still has to be the best explanation yet... thanks again..
Your comment means a lot to me JOGO - thank you!
"You now understand [...]"
Yes I do sir. Thank you very much!
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.
Great video! Explained in simple words.
Thank you very much! I appreciate your kind words :)
Thank you for that straight forward, and simple to understand comparison of the two, and a simple explanation of which situation to use which. I did not understand this before I watched this videos.
Thank you for you comment and kind words. I'm glad I could help :)
You just saved me a lot of trouble. I am building a lab power supply / breadboard, and want 1.5v 3v 5v 6v 9v output, from a 12v dc input. I have already bought the lm780x's in order to do this, but I have been wrestling with the heatsink design and attachment issues. Now I can use 5 lm2596's instead and not have to deal with the pain in the ass heatsink mess.
In a situation where one needs both 12 volts to power LEDs or a relay, but also needs 5v for CMOS logic, do you think an LM7805 would be appropriate since it wouldn't heat up very much since the CMOS chips don't consume much power?
Top shelve video. Many, many thanks. Everything is crystal clear, no silly comments. VERY PROFESSIONAL. Congratulation
I'm very happy you liked the video :) Thank you so much for your kind words!
Все ясно и по делу! Спасибо!
Excellent Video -- informative, clear, concise script. Good camera work, good sound, well paced and edited. Very well done! Thank you!!
To be a bit pedantic on one specific point(there are more points I could mention): At approx. 4:10 you are not measuring the power consumption but due to the fact that you measure the current(under the assumption the voltage is constant 5 Volt and does not break down) we can calculate the power V*I(under the assumption that the current is constant too, otherwise we have to take the change in current over time into account to determine the power as a function of time) and if we measure the on time, we can also easily calculate the energy. Nevertheless you made a really nice introduction video, keep on doing this. :)
+Sebastian Au Thanks for the info and your understanding, I will have to check all my calculations again and I might do a follow up video to correct all mistakes. Every such comment is really helpful :)
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?
The comperision is so cleared like water as you described. Thanks a lot .
very educational. thanks for posting
+pebre79 Thanks for your comment :)
You are so informative and detailed. I was going to use a buck converter for a light on my quadcopter but you mentioned about interference and potentially saved me from a crash.
+SlNlST3R Thanks for telling me that :)
However, when it comes to quadcopters - I'm not sure if a buck converter would make any difference. These wireless controllers are quite resistant to interference. A couple of practical experiments should clear things a bit.
very good video
thanks for that!
Regards from the Netherlands
R.Rob.
+R. Rob. Thanks a lot Rob! :)
Good video with your clear voice and without unbearable playback music.
Excellent information. Love From India.
Thank you very much :)
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.
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.
Even back when this video was made I could find at least 2 models of buck converters on ebay for 75 cents each.
Fast forward a few years after that and the mini360 that you have with pins soldered onto if can be commonly had for less than 50 cents each ..go buy a 10 pack and enjoy.
The mini 360 is probably named for its switching frequency of around 360Khz, I hope no one is designing new AM band radios, but if they are the interference should be minimal, as the inductor is enclosed. You can also choose other models with different operating frequencies, such as the other 2 you showed at the beginning of the video, the larger unit has about an 80Khz operating frequency and the other one can be tweaked up to 500khz. There are cheap buck ICs out there that operate at up to 4Mhz switching frequency, most of those are a dollar or two more expensive though.
Someone else mentioned that you forgot the ripple on the output, so you should still add a 10uf decoupling cap to the output of the buck module.
very useful video,Thank you so much
+Nick Mukbaniani
Thanks a lot! :) Sorry, I couldn't reply sooner - I was on vacation.
Should we use Buck Converter instead LM7805? Help us to choose best suited from varieties of Buck Converter?
A quick explanation of why the difference in the power consumption might have been useful for some. A 7 volt feed would have been a closer match, not that it would be practical but would illustrate why the power difference.
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)
Is there a way to shield the buck converter for radio sensitive devices, for example the esp8266?
+bugs181
I guess an ESP8266 should work ok with a buck converter.
+bugs181 Yeah that should work, if not use a buck converter that provides a bit higher voltage that is needed and than a linear regulator, if you want to spend money buy the LT3080 a really really neat linear regulator, also good for building power supplies... ^^ but of course if you need a constant voltage one of the standart linear regulators would be cheaper ;-)
+Sebastian Au I've used the ld1117 as a 3v regulator for the esp8266 - it will handle the current needed. A buck converter to 5v the other side of that might be nice - but quite bulky. It is a problem with battery life on robots - always space vs weight vs battery life.
low noise versions whit inside coil
www.ti.com/tool/tida-00532
That's a good one, thanks :)
I'm new to buck converters. I bought one LM2596 model to power a simple Arduino Uno with LCD at 9V. It works very well and I don't think I'll use the LM317/78xx anymore unless its mission critical.
A very good video, I enjoyed it. Other good examples of the differences is how the efficiency of the linear regulator gets worse as the difference between input and output voltages increase, and the limitations from minimum Vin (drop out voltage) and minimum Iout (discontinuous operation).
+Marc Visconte Thanks a lot Marc :)
You're right, the higher the difference between the input and output voltages, the worse the linear voltage regulator performs.
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
This video gave me the entire knowledge which I was searching for... Thank you sir
I would be glad if you do a video explaining the differences of different buck converters, actually, in my opinion the best step down in most of cases is the MP1584EN, that maybe is the one that you used in the video, it works at above 1Mhz doesn't need a heatsink but can take maximum 29V at input, while lm2596 is bigger, at higher current dissipation need a heatsink, it works at 150Khz, but it can take an input voltage about 35V and then there is the lm2596hvs wich can take almost 60V at input, also I bought on amazon six MP1584EN at the price of 10€ that means that you have a ready to use module for less than 2€, while the lm2596 both version cost around 10€ each of them, so then in my case MP1584EN is the best choice.
A lot depends on your application and budget. It would be quite difficult to compare these buck converters, because there are so many possible applications. Such a video is a good idea, but it would definitely take a lot of time. I must admit time limits me the most, because of my regular job. I wish RUclips was my regular job. Maybe some day...
Its meant to BE used with a heat sink
I've attempted to use several different buck converters with 3 motors (120x120 fans actually). These motors (fans) draw 80mA.
All the different buck converters lasted around a day, then they were fried.
Now I use a simple LM317 and it just works all the time. I don't use a heatsink.
I believe this is due to that the motors send spikes back into the buck converters (at a much higher voltage than is fed into them), so I don't use buck converter for anything like relays and motors.
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 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.
good idea to heat coffee cup
You would have to use a bunch of LM7805s and a bucket of electricity ;)
Hi from Sunny South Africa - I prefer the LM 7805 because 1) Temperature is easily sorted with simple aluminum heat sink 2) the ripple voltage is much cleaner than buck converters 3) Cost is much cheaper 4) ZERO EMI issues - ever
One of the best electronics videos I've seen on RUclips - great stuff! I feel like I've learnt a lot, and only in 7 mins
Thank you so much for posting your comment and kind words :)
cool man, thanks.
I liked that formula for calculating the heat of the linvreg in Watts.
voltage difference(Vin - Vout) x consumed/used current ( A/mA) = Watts
( 9 - 5 ) x .5 (=500mA) -> 4 x .5 = 2 Watt
I was calculating power consumption on the input. It didn't have anything to do with the heat.
excellent information. Answered every question I had about voltage regulation and save me a TON of time and research on my project.
Thank you! I'm glad I could help you :)
You should comment more on the noise issue associated with the switching in the buck converter and how to at least reduce it by proper use of capacitors and ferrite beads
I totally agree with you, but my channel is very small and I have rather limited resources, so I don't have an oscilloscope. It's quite difficult to talk about noise without showing it on the oscilloscope.
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
I really enjoyed this video. In the top part I see you updated some wattage calculations from evahle's comment,
but something seemed fishy still.
You stated:
There are 2 mistakes in my calculations:
1. 5:02 - 5:08 - correct calculations should be: (12V - 5V) x 0.42A = 2.94W
2. 5:17 - 5:23 - correct calculations should be: (12V - 5V) x 0.22A = 1.54W
I think you are trying to calculate the power wasted by the voltage regulators to compare them to each other. This can
be found by subtracting off the power used by the hard drive loads from the energy used by the whole system.
I believe the (updated or 'fixed') equations are wrong because they assume the system input current and output load current are the same.
You can see this by expanding the equations to give the difference in power between the power consumed by the system at its input, and the power consumed by the load at the output:
regulator power = input power - load power
2.94W = (12V * 0.42A) - (5V*0.42A) // for the linear regulator
1.54W = (12V * 0.22A) - (5V*0.22A) // for the buck converter
But you stated at 3:42 into the video that the hard drive load draws 450mA from the 5V regulated output.
This is more that the input current as measured in both kinds of regulators. So these equations can't hold.
They would be true for a resistive voltage drop, where the input current to a resistor is the same as the output, but not for these regulators.
Computing the power consumed by just the regulators:
12V x 0.42A = 5.04W for the linear regulator.
12V * 0.22A = 2.64W for the buck regulator.
(these values are what you calculated in your video)
Subtract the useful power consumed by the hard drive load from the total input power to give the net wasted power consumed by the regulators.
As stated at 3:42, the hard drive load uses 5V * 0.45A = 2.25W
The net consumption for the linear regulator is: (5.04W - 2.25W) = 2.79W
The net consumption for the buck regulator is: (2.64W - 2.25W) = 0.39W
So what is the ratio of power consumed by the different types of regulators using these new numbers?
In the video you said that the linear regulator uses over 90% more power than the buck converter at 5:23.
This is I believed based on the simple ratio of wattage used. i.e. (5.04W/2.64W) ~= 1.909.
The new ratio of regulator powers: (2.79W/0.39W) = 7.15. In your methodology, the linear part uses more than 600% more energy for this load vs the buck converter.
I went back and applied the same efficiency methodology to the so called fixed wattage calculations.
Strangely, the 'fixed' wattages gave the same 90% power figure: (2.94W/1.54A) ~= 1.909
Strange because buck converters should be far more efficient at higher voltage drops from the source since the power does not need to be converted completely into heat.
---------
Sorry for my long windedness. Let me know what you think. I've been known to stow my head where the sun don't shine. :)
First of all, sorry for replying so late. I didn't have a chance to use my computer for quite a while.
Wow, you really got into this subject and you are so right in most part :)
The calculations seemed very simple, but I got confused by several comments. If I recall correctly, I was calculating just the power consumption of both regulators with the load on the input (12V) of both regulators, not the output (5V). I didn't calculate the heat dissipation, but most viewers thought I did. That's why I got confused myself.
I get it. You were originally just calculating the relative system efficiency at the 12v inputs. I guess I just nerded out.
As simple as that :)
Thanks for posting this. A nice clear explanation of the two options.
+Choppington Otter Thanks a lot :)
Great video. Being new to electronics this explained a lot I did not understand. I'm having this exact heat issue on present projects and a buck converter should fix the issue. Thanks.
Cool, I have been trying to figure out how to set up a relay for my daughters Jeep. The radio has a power drain and keeps running her battery down. The Jeep shop wants over 500 bucks to fix it, so another mechanic just pulled the fuse and she is without a radio. It works OK when you are driving the rig and only drains when the car is turned off. So my thought was to put a small relay between the power to the radio and the radio itself. The relay's that I have are all controlled by 5 volts, and would be switching 12 volts. My plan is to pull the switching voltage from an accessory fuse, so when she starts the car, the radio can have power, and when she turns the car off, the radio will again be isolated from the battery. I believe the little power supply is just the answer to my problem of getting an isolated 5 volts to run that relay! Going to build a small box with integral fuse, then plug the wires for that box into the fuse socket of the radio, plug the radio plug into my box, and hide the box so it isn't in the way. Thanks a million for laying this out for me, I already have all the parts for this build so I will get on it soon!
had a bag of 10 of these regulators this week that you show at 6:03 , I needed to drop 11-14v to 8.3 for a lipo charger, worked before soldering, but failed once output wires soldered, the output was going short, i think theres an issue with mine in the multilayer board that solder wicks somewhere. I have had no issues with the blue pcb version with the preset voltage solder pads on the rear, i'll stick to buying those ones in futre. all boards worked before being soldered
I have a boost converter. that strangely works as a buck converter if you set the boosted voltage output above the input voltage by 1 or 2 volts or so.
and take output from positive power input. and positive power output of the boost converter.. it will give out only 1 volt! for example 5v. and you set the output to 6 or 7v. then take output from there. you get only 1v
so I can technically use this as a buck converter even though its meant as a boost converter.. (I did test it. and it was able to output 5 amps where as input was less than an amp at 12v with a dummy load.)
You need a reasonably steady input supply to get a steady output supply though when using it like this.
I call it the buck-boost mode because it can boost and buck at the same time when its like this.
It seems to take the difference in voltage between the boosted output. and the original input. and outputting the difference.
Its a miracle as well because I originally ordered a buck boost converter. and they sent a boost-only converter.
but I still made it work as a buck boost converter by using it this way. really interesting.
That's a bit strange behavior. Where did you order this beast?
Well it works with pretty much any boost converter where the negative lead is joined on input and output (forgot what thats called)
You just get output from the positive input (as the negative lead) and positive output as the positive lead and use that
You need to first boost the voltage a little over the input voltage to get an output from there. so the maximum voltage is slightly under the max output voltage of the regular boost portion of the boost converter.
give it a try and measure with your multimeter. You can boost and buck in doing so like this. just make sure your input supply is somewhat stable and your not using too sensitive of a load. 50-200mA or so on the output will keep it stable.
Sometimes when shutting off the voltage will spike up a little. thats why its good to have a small load on it to prevent that.
It works great for my 12v power supply rated 2 amps reducing the output voltage to 5v and I can get more amperage than the input. so it works great. my audio amplifier runs on 5v. so thats what i use for it with this.
all boost converters also work as buck converters; but not all buck converters can also boost your voltage.
Nice presentation. I was wondering about standards for comparing buck modules and I now assume the answer is to get ripple specs.
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.
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.
Great Video.. Glad I watched till the end. I was considering a buck converter for a portable amplifier. I never would have known they can create interference. Good tip
wickedbadretard Thanks for your comment, I'm glad I could help.
You can find many different devices on the market: buck converters, boost converters and buck-boost converters, which is a hybrid of the former two.
Hello, i am going to uso a reductor made with an LM317. The input Voltage is 24V and the output voltage must be 7V, the current that i need its more or less 400mA. i would ask you if I need a big sink for the high temperature, or maybe i can use one like you show in the video.
Another question that i have is that if i use that buck converter, can i use with an input voltage of 24V, and output voltage of 7V, and a current of 2 A?
Thank you very much (sorry for my english, i am from spain)
PD: Where can i buy one of the buck converter that you use on the video?
Literally the exact video I needed right now.
That's great to hear/read :)
2023, this video is very well explained for a newbie like me
About those buck-boost voltage regulators, if we step down or up, do we loose power?
For example if I want to power an 8v device with a 2 cell li-ion would it be better if I use a 3 cell battery and step it down to 8v?
As I understand, the conversion efficiency of buck converter is about 90% so you will only lose negligible energy (I am just a student and have no prior experience using any buck convertors so please do refer other sources)
Both buck converters and linear voltage regulators are improved by adding 100nF ceramic capacitor across the output.
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 .
A video is amazing to watch specially for the peoples who doesn't have enough knowledge of electronics
Thank you very much :)
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.
Good video. But you did not mention what happens to the output voltage on bothe when the input drops or rises
Very nice lesson, thanks master. Clear and concise.
+Hernan Ortiz Thanks a lot :)
Buck converters produce a lot of EMI on SW-MW-LW bands but they also produce pretty dirty output which swipes out those bands if you use your PC with SDR receiving devices. It's curable with LC-filters though.
Thanks from SriLanka !
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.
good video but a buck converter can be built with LMxxx. I see them all over on Craigslist, and they always have some small 'heatsink' attached. I think you should point out switching regulator vs linear as the main point
Sure, you can build a buck converter yourself, but there are several tricky aspects. Additionally, you'll probably pay more for the components than for the whole buck converter.
Yes, that's true - buck converters are a type of the switched mode power supplies. Since linear voltage regulators drop voltage, I wanted to compare it with the buck converter and not the whole switched supplies family.
This video made things cristal clear. Which regulator do you recommend on a solar power charger?
Thank you very much. I would probably use a buck converter on a solar charger.
Very handy and well explained. Great comparison. Cheers
Thank you so much! Cheers :)
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.
Thank you so much for your video. Your video gives very clear understanding of the difference between a regulator and a buck converter.
One question : I think the power consumption is written as
P[W] = (Vin-Vout)*Current.
When we calculate the power, we need use 7 volts (=Vin-Vout = 12-5) instead of 12 volts.
Thanks a lot!
I was calculating the input power consumption, which is my dummy load + the buck converter/voltage regulator.
The potentiometers on all my buck converters keep becoming unresponsive after a few weeks of usage of the converter without me even changing the potentiometer setting.
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 :)
If you need low heat AND low noise use a buck converter from the supply and then a linear regulator afterwards. Set the buck converter output voltage to just above the dropout voltage of the linear regulator. Low dropout linear regulator are best for this.
Both have their place in circuits, but for reliability, I'll take the linear regulator with a good heat sink over the dc ~ dc converter any day, and that's what 35 years of experience tells me.
I couldn't agree more. DC-DC converters are much more efficient in most situations, but reliability may be a completely different story.
Modern Dc-dc MTBF is very similar to linear regulator.