HACKED!: Adding a Current Limit Feature to a Buck/Boost Converter

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6 жыл бұрын

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DIY Buck/Boost Converter: • DIY Buck/Boost Convert...
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More project information (schematic, pictures,....) on Instructables: www.instructables.com/id/Addi...
Parts list (incomplete, see Instructables for more, affiliate links):
Aliexpress:
1x Buck/Boost Converter: s.click.aliexpress.com/e/_dTe...
1x LF33 Voltage Regulator: s.click.aliexpress.com/e/_dT0...
1x 10nF Capacitor: s.click.aliexpress.com/e/_dU4...
1x 10µF Capacitor: s.click.aliexpress.com/e/_d7d...
1x 0.1Ω Current shunt: s.click.aliexpress.com/e/_dSy...
2x 3.3kΩ, 2x 100kΩ Resistor: s.click.aliexpress.com/e/_dTP...
1x MCP602 OpAmp: s.click.aliexpress.com/e/_dTv...
1x 10kΩ Trimmer: s.click.aliexpress.com/e/_dTF...
1x UF4007 Diode: s.click.aliexpress.com/e/_dYR...
1x Voltage/Current Meter: s.click.aliexpress.com/e/_d8l...
Ebay:
1x Buck/Boost Converter: rover.ebay.com/rover/1/711-532...
1x LF33 Voltage Regulator: rover.ebay.com/rover/1/711-532...
1x 10nF Capacitor: rover.ebay.com/rover/1/711-532...
1x 10µF Capacitor: rover.ebay.com/rover/1/711-532...
1x 0.1Ω Current shunt: rover.ebay.com/rover/1/711-532...
2x 3.3kΩ, 2x 100kΩ Resistor: rover.ebay.com/rover/1/711-532...
1x MCP602 OpAmp: rover.ebay.com/rover/1/711-532...
1x 10kΩ Trimmer: rover.ebay.com/rover/1/711-532...
1x UF4007 Diode: rover.ebay.com/rover/1/711-532...
1x Voltage/Current Meter: rover.ebay.com/rover/1/711-532...
Music:
2011 Lookalike by Bartlebeats
Ecstatic Wave, Jens Kiilstofte
machinimasound.com/music
In this episode of HACKED! I will have a closer look at a common buck/boost converter and create a small, additional circuit that adds a current limit feature to it. With it, the buck/boost converter can be used just like a variable lab bench power supply.

Пікірлер: 596

@kristiandelchev7362 3 жыл бұрын

To make full CV (constant voltage)/ CC (constant current) operation - the voltage and current feed-backs are to be combined into the FB pin. Whoever is higher will take control. Most commonly people use a resistor divider (to FB pin) for the voltage feedback and current sense amp for the current feedback. How to combine them? The simplest is to connect the current feedback signal to FB pin via diode. The drawback? - diodes have voltage drop changing with temperature *by 2mV/deg C). The most accurate solution is to "idealize" the diode by op amp. The current feedback signal is applied to the non inverting input of an op amp. Its output drives an NPN emitter follower, whose emitter is connected to the op amp inverting input. The circuit can only pull up, but not down i.e. does affect the voltage control in normal operation. Should the current limit be exceeded, the current feedback will take over

@anugrahkorambeth431 6 жыл бұрын

eventhough I donot understand anything, I still watch your videos and I like them. Please keep em coming 👍👌✌

@llama1917 2 жыл бұрын

Software Engineer. Always have to remind myself that with circuits and hardware in general you cannot just "get started and refactor when you know what what you're doing more" 😎

@yashsvidixit7169 6 ай бұрын

And that's where simulation enters the chat.

@SayanMitraepicstuff 6 жыл бұрын

The two main ways Scott starts his video: -Recently... -In ze previous video...

@greatscottlab 6 жыл бұрын

But not this time

@DarkSlayer-xk3fb 6 жыл бұрын

XD lol

@pablobski 5 жыл бұрын

totally!

@fertilizerspike 4 жыл бұрын

"let's find it out!"

@noelsherron 3 жыл бұрын

“A while ago”

@shariqzaman2834 6 жыл бұрын

I was searching for this type of project for a long time :D ..Thanks GreatScott :)

@epiendless1128 4 жыл бұрын

The issue I have with differential amplifiers for current sense is that they are very sensitive to errors in the resistor values. A 1% resistor error will give an output error of 1% of the _supply voltage,_ which is comparable to the thing you're trying to measure. Alternative is to use a current sense amplifier. Silicon Labs SI8540-B-FWR is just one example.

@thecombatengineer7069 6 жыл бұрын

This is very clever and I have enjoyed watching your skills and experiments progress. Thanks for the dedication mate!

@jeffreygoodson2563 4 жыл бұрын

I LOVE the way you explained this! You're a great teacher. Thank You!

@JKnight89 4 жыл бұрын

This video helps me. I have a junk benchtop power supply that eventually I wish to rebuild, so this gives me a place to start looking for possible starting point. Thanks!!

@ReagueOfRegends 6 жыл бұрын

I'm always left wondering, how many people watching here are electrical engineers vs. hobbyists? :)

@philxcskier 6 жыл бұрын

I'm sure there are a ton engineering students.. I happen to be studying mechanical engineering, and it's nice to be able to check these out whenever I have no idea what a circuit does.

@Lovreli 6 жыл бұрын

Spurdo Sparde both lol

@vaguedirector_7342 6 жыл бұрын

ECSE student here, binge watching all the good electronics channels

@aunreza 6 жыл бұрын

Electrical engineering student here. I watch these videos for fun but i might build this circuit for a project.

@spudhead169 6 жыл бұрын

Hobbyists are 100x smarter.

@TheOleHermit 4 жыл бұрын

This is exactly what I needed to know/do! Thanks! While using buck/boost converters to build a DIY solar charger on a LiPo power pack (w/o mfr's circuitry), I've fried my rework station's internal 15 VDC PSU, a buck/boost converter, a buck converter, a boost converter, and a solar tracker... so far.🥴 Unfortunately, I was unable to keep up with the video. So, I'll watch it about a dozen more times and head to your project info links. Ha! just noticed a link to your DIY LiPo solar charger video. (How did you know?) See ya. 😎

@Trancelebration 6 жыл бұрын

Good idea is to add a bit integration to comparator circuit. Something around 10nF between output and inverting input does the trick. Much cleaner output voltage and less hissing sound from inductor.

@45llamas 6 жыл бұрын

I love your videos and how you explain it function so clearly !!

@fmdj 2 жыл бұрын

When Great Scott has a video on the exact thing I'm trying to do... AWESOME! thanks!

@Jones12ax7 6 жыл бұрын

I used an ATX power supply with one of these buck modules to make a crude powersupply. It worked so well that I plan to increment that and this circuit will be very handy! Thanks!

@rainbowspeedy 5 жыл бұрын

Ich don't understand what Scott is talking about. But I love his voice. That's why I watch his videos.

@ritvikaneesh5980 2 жыл бұрын

I just started electronics a few months ago and I have learned so much from these videos. I have recently made my own power supply, no current limit feature though this video should help

@tommihommi1 6 жыл бұрын

Another advantage of lab PSUs is a much, much cleaner voltage. Try to power a radio with a circuit like this and you'll see what I mean

@greatscottlab 6 жыл бұрын

True

@mattimhiyasmith 6 жыл бұрын

You should be able to reduce the ripple by loading the buck/boost converter with high load but kinda makes the current limiting in this video pointless :P or use a LDO or RC in series to from the converter

@vaguedirector_7342 6 жыл бұрын

I'd just add an LC filter to the output for lower noise operation.

@TheOswald42 6 жыл бұрын

I see, LDO, RC or LC filter.....is there more solution for cleaner voltage?

@brucefox6580 6 жыл бұрын

A linear PSU perhaps.

@pankajroy5124 6 жыл бұрын

Great Scott YOU ROCK!!!!!. Another great video. You are helping and motivating youngsters to learn electronic. Good work. Keep it up.

@apeman9001 5 жыл бұрын

Spoken like a true politician! I take it you belong neither to the EE group nor the hobbyist group, but the bureaucrat group. Just kidding!

@houseofelectronics5869 6 жыл бұрын

Great video @GreatScott. Your channel is a perfect guideline for any electronics beginner. I learn a lot from each of ur videos. Thanks man :)

@greatscottlab 6 жыл бұрын

You're welcome

@marlonmartins82 6 жыл бұрын

This is exactly what a was trying to learn this week. add current limiting to my power supplies. thanks!

@navjotsingh0006 5 жыл бұрын

I enjoyed it alot and you created what i wanted to have in my little electronic project but its not easy for me to build just like you did it but great video its always fun to watch your videos.

@maxximumb 6 жыл бұрын

Thanks for posting this.It's exactly what I'm looking for.

@owalkmachinemaishitechdobr3674 4 жыл бұрын

Your videos are amazing! Thanks to share knowledge and your experiences!

@briannielsbergh 6 жыл бұрын

Your videos are just so cool, thanks for sharing your knowledege :P

@jensschroder8214 3 жыл бұрын

You can also switch off a buck converter by introducing a feedback voltage greater than the reference voltage. In the case of a boost, the output voltage would then roughly correspond to the input voltage.

@rtesimpson 6 жыл бұрын

Very neat handwriting and schematics!

@Darieee 6 жыл бұрын

Amazing as always !

@matejhusek6855 6 жыл бұрын

Thanks!!! I Made it and with dome changes i Made my super Power supply!!!! Very good video.

@BlackXeno 6 жыл бұрын

Just to be sure if I have understood the feedback as you have explained: when you see the output voltage swinging a bit on the scope, that is the switching noise, not the error direction of the control feedback.

@greenman2262 3 жыл бұрын

GREAT Scott a well thought out and worth while doing little project thanks.

@electroumit 6 жыл бұрын

Thank you. Your voice and speech is great. I very like.

@jayzo 6 жыл бұрын

I've learned more _useful_ information about electronic circuits with the likes of GreatScott than I did in school.

@Beakerzor 6 жыл бұрын

wow, what a well organized tutorial! well done!

@engician7620 6 жыл бұрын

I don't understand any thing !!! But I love watching your videos It gives me a kind of satisfaction.😌🙏💁

@extrims70 5 жыл бұрын

Hope somebody has already caught electrical schenatic typo at 05:49 - differential amplifier IC1A won't work the way it shown :( Non-inverting pin.3 should be connected to junction between R2 and R3. Anyway - that's is great work, Great Scott!

@vaseemmehrancp9372 3 жыл бұрын

Real blend of creativity , fundamentals and hacking

@michaelumenyi6907 6 жыл бұрын

Your videos always exists me!!

@PropaneTreeFiddy 6 жыл бұрын

0:45 That NOISE!!! You can literally see the LED flickering in the footage. If you want to use a buck-boost converter for anything that requires a fairly stable voltage, I highly suggest adding a good amount of filtering!

@toastinat0r 6 жыл бұрын

great video! Id love to see a Current Limiting circuit for a High Amperage High Voltage AC Circuit (600v-25a)

@dave_dennis 6 жыл бұрын

I've done this many times. The problem I've sometimes had was that the high side of the feedback resistor would sometimes exceed the common mode input capability of the opamp. This has often forced a careful selection of a high voltage capable opamp.

@TheSliderW 6 жыл бұрын

Very interesting as always. : )

@asasif7 6 жыл бұрын

Greeting from PAKISTAN.. Greatscott you always do a great job. You are a great teacher for me. i learnt using arduino totally from you.

@nitinnahar7713 4 жыл бұрын

Really I would say the video is very excellent. You are really Great Scott

@tusharsinghrajawat9405 5 жыл бұрын

Your videos are awesome

@pradipkantimandal1521 5 жыл бұрын

Great Scott... U r great... Very neat and clean explanation.. ::))..

@richardnanis 6 жыл бұрын

Excellent video and tipp! much appreciated! Did you also investigate the behavior of the buck/boost converter when input voltage drops below 3.8 V? I figured out that the output rises suddenly to its maximum when input voltage drops below 3.5V. This would be fatal if powered by a liion e.g. that suddenly drops below 3.5V. Then it could happen that the output of the buck-boost rises to 30 or 40 V destroying an led that might be connected to its output (or anything else). I think i got exactly the same buck-boost converter from ebay (chinese seller) - which cost me only little more than 1 euro.

@Nick-zp7hk 5 жыл бұрын

wow ..... you are great man, you make great videos ........ super !!!!

@RegiPavan 6 жыл бұрын

Thanks Scott for another great vídeo...

@greatscottlab 6 жыл бұрын

Glad you liked it :-)

@tanyalobyam 5 жыл бұрын

Great video always

@tansateknisi3541 4 жыл бұрын

Owesome explanation.... bravo..

@ergindemir7366 4 жыл бұрын

It might be a good idea to use a pot for the feedback resistor to calibrate the opamp for the precise current measurement.

@BukkitViper 6 жыл бұрын

You really improved the quality of your videos, keep up the good work! Also your german so thats a plus. Can you tell me how to build a li ion charger with arduino? I need to measure the current with a shunt resistor but the values from the ADC just make no sense. thanks.

@kishorgoodday276 3 жыл бұрын

Thanks for this great hack bro...i searching for this type of hack...😍

@FarhanRashid123 6 жыл бұрын

Luv ur videos . Ur awesome

@damascenoalisson 6 жыл бұрын

You can easily buy current-limiting converters from eBay... But DIY is so much better haha Great project btw! :-)

@stalwartekwere2157 3 ай бұрын

Nice project

@thomasgotthulk3629 6 жыл бұрын

comes in handy, thanks

@plamenpetkov6958 5 жыл бұрын

There are ready made CC, CV Buck Boost converters, with additional trim pot for current limit adjustment. They typically use low side current sense resistor (shunt), making it easier to process the current feedback signal. Typically the current feedback signal after non inverting amplification is fed to the FB pin via diode. The FB pin is controlled by the higher of of voltage and current feedback signals. Nothing wrong using high side current sensing...but the accuracy of the simplest 4 resistor diff amp even with 0.1% resistors could exceed 2% due to unwanted sensitivity to voltage due to resistor mismatch. TI and AD have an extensive range of tiny current sense amplifiers, more suitable for this role than a general op amp (comparable on size and cost).

@anandsingh8987 4 жыл бұрын

This was awesome..

@sakugava 6 жыл бұрын

Another great video

@MakerMike-bx5ms 6 ай бұрын

Thank you! Nice job!!!

@phrankus2009 3 жыл бұрын

The beauty of Scott not glossing over the finer details is that it inspires me to "really" study the circuit or concept intensively, by consulting MANY sources (including the Wiki, even) until I have a truly intuitive (deep) understanding of the FLOW, the LOGIC, and the MATH. .. I do not care how long it takes. .. I resent being rushed through anything that I do not yet "fully own". .. Scott seems to OWN the knowledge, which he shares, and his uncompromised, comprehensive and detailed presentation illuminates the degree of my shortcomings. .. This allows me to fully remediate my deficiencies, however frustrating.

@kshysztof9649 Жыл бұрын

Yes, absolutely ! When I first watched the Nixie tube video, I didn't knew what was going on, but after few hours of research, I came back to the video, and could clearly see what problems and solution he has used.

@zaboky 6 жыл бұрын

Thank you!!! nice video!

@PezDJ 6 жыл бұрын

Awesome :D! You shoult teach us how to do a diy VFD for AC power :) if one would want to drive a ac motor to build a lathe or something connected to 230v :)!

@cybaneticcybanetic441 6 жыл бұрын

great video Scott. can you please make a video on an SMPS power supply build??? it has proven difficult for me to understand

@ajaya1542 6 жыл бұрын

Thank you very much I asked for it you did it again I thank you very much

@MilliHardTech 6 жыл бұрын

cheers from India..:D

@passtranelectronics 6 жыл бұрын

excelente amigo

@nosafetyswitch9378 5 жыл бұрын

Without really noticing, everyone here is being taught/shown basic control theory principles under their noses! Well done! Usually its scary shit!

@budandbean1 6 жыл бұрын

Man, you are pretty amazing and one heck of an instructor! It's like you make almost everything understandable. Please continue your fine work... :-)

@greatscottlab 6 жыл бұрын

Thanks for the feedback. I will try my best.

@apurvsharma1261 6 жыл бұрын

Luv ur videos

@ashwaniyadav3661 6 жыл бұрын

thanks alot bro it helping us alot

@jimthvac100 5 жыл бұрын

This is cool knowing how to do this, but I would probably just buy one of the many buck converters that include an adjustable current limiter in the design.

@miniwarrior7 5 жыл бұрын

Zero challenge or understanding of the components you're using means when they don't work you just buy more

@Roy_Tellason 4 жыл бұрын

That's exactly what I did, only the board has _three_ trimpots on it, not the two that you'd expect. And it doesn't seem to want to work properly to drive a 10W LED. I'm in the process of trying to figure out why...

@fmdj 2 жыл бұрын

Yeah but you have to wait for it to arrive from China or wherever. I like to be able to build things with the stuff I have lying around. As a programmer I find there is a lot of beauty in creating complex things from a limited number of primitives. So as an electronics hobbyist endlessly buying new components doesn't satisfy me. If I were building a commercial product that would be another story.

@kane100574 6 жыл бұрын

Excellent!

@mickg8340 6 жыл бұрын

Very interesting idea. I was wondering how you would do something similar to this. Lol my thoughts involved a 555 timer IC to increase or decrease the switching time of the feedback to limit the current, which iswhat i believe you are using. Lol i havent checked your schematic yet

@galacticgamers8705 6 жыл бұрын

I'm only 10 and I love these vids.

@RealDjMarkuZ 6 жыл бұрын

Great stuff great Scott!, I always follow your channel. As an electronics fan I always wanted to do a kirlian camera as an experiment for myself, yes that camera that supossedly takes photos of the aura, it is possible to do that with a circuit?

@aniketshinde6743 6 жыл бұрын

greetings from India.. great Scott luv ur all videos keep going..

@greatscottlab 6 жыл бұрын

Thanks mate :-)

@kulde3pverma160 6 жыл бұрын

Aniket Shinde hi aniket

@vishal01mehra 6 жыл бұрын

one more from India.😊

@pardeepk21 6 жыл бұрын

Count Me In Too :P

@sumit_kashyap.. 6 жыл бұрын

One more Indian ;)

@jossydornelles7606 3 жыл бұрын

GreatScott! Thank you for the class on this circuitry! I assembled the circuito but, for any reason, I was not able to control the output current. I am using a step down LM2596S-ADJ (yes, the feedback pin is 4), and I would like to know: should I have to disconnect pin 4 from the board? How much current I am able to control?

@brainpoweredelectronics3351 6 жыл бұрын

Very useful hack. I was looking into doing something as elegant for a a linear regulated power supply. Perhaps you could could think of a similar way to Implement current limiting using an Lm317?

@blackbrayn 6 жыл бұрын

Brainpowered Electronics i just burned a lm317 with overvoltage , i was lucky to have a spare lm338 , this reminds me to buy some more.

@ruimvp 5 жыл бұрын

Hello GS. In this type of power supplies can i use a big electrolytic capacitor at output, like in a linear power supply, to avoid ripple? Thank you. Keep the good schematics.

@milanhlavacek6730 4 жыл бұрын

Due to the quite high frequency i thin its better to use film or ceramic caps

@TheJay6621 6 жыл бұрын

Awesome.. Thanks for your time and efforts.. love from INDIA.

@TheJay6621 6 жыл бұрын

mrco74 flush it.

@mja2239 6 жыл бұрын

lol

@kristiandelchev7362 3 жыл бұрын

It is better to use dedicated current sense amplifier like INA193. The proposed op amp base design has two main deficiencies:first, with gain of 30 the op amp inputs get too close to the power rail. Many op amps have limited common mode range on the upper side. The second problem is the effect of tolerances between the paired resistors. This results in sensitivity to voltage, not just current. Laser trimmed resistor quad IC like LM5400 can help, but it is easier to use dedicated current sense amp.

@meanxmeanx1763 6 жыл бұрын

It would be interesting to see the voltage on a scope. I fear it would be more PWM style than flat.

@muhammadjibrael3649 6 жыл бұрын

Very helpful

@intelligentprocessorai396 2 жыл бұрын

Great engeener ever!!!

@noudlindeman1931 6 жыл бұрын

great vid

@ElvisTafaPhotography 6 жыл бұрын

Love your videos. Can you make a video how to make a battery metter? For any battery. Thanks!

@manliomalavolti9640 3 жыл бұрын

Great video, thx! I wonder what could happe if a boost converter designed to boost to 12V, sees an input (from solar panels in full sun) coming @ 16V. Would it fry?

@sumit_kashyap.. 6 жыл бұрын

Great video.. can you please make tutorial on PID controller.. :)

@greatscottlab 6 жыл бұрын

On my to do list

@massimookissed1023 6 жыл бұрын

Sumit Kumar , setting up a PID to be useful is a bit of an art in itself.

@mayuralakshan9130 6 жыл бұрын

Like from sri lanka.. !

@MCsCreations 6 жыл бұрын

Fantastic work, man! Do you think it's possible to do the same to a boost buck converter that uses a XL6009? I have one identical to the one you used. BTW, what about short circuit protection? Would it add it too?

@greatscottlab 6 жыл бұрын

Same theory and my circuit should apply to all buck or boost converters with a feedback pin. And at the end of the video you can see how I short the output of the converter. So yes, this allows a short circuit protection.

@jamest.5001 6 жыл бұрын

GREAT VIDEO!!!..,

@pbsolutions119 3 жыл бұрын

Thank you very much

@kvlpnd 6 жыл бұрын

Great video... You are excellent at editing and redesigning circuits. I think you should have done Electronics Engineering rather than Electrical Engineering.

@theofilocc 6 жыл бұрын

Could you please explain the purpose of R2 and R3 in the circuit you designed? Great work btw.

@sudiptimalsina178 5 жыл бұрын

You are the great.

@vojislavhoc4467 6 жыл бұрын

Great video as always,greetings from Serbia,and i have one question how can i make fine-course adjustments for voltage and current for my DIY variable power supply?