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Tutorial: DC/DC Buck Converter Voltage and Current Regulation

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How a DC/DC converter handles the relationship between voltage and current regulation. Check out B3008 6~32V / 0~30V LED Display CNC DC-DC Constant Voltage Current Buck Module http://www.ebay.com/itm/B3008-6-32V-0-30V-LED-Display-CNC-DC-DC-Constant-Voltage-Current-Buck-Module-/321458830703?roken=cUgayN&soutkn=ujK4ZF via @eBay Check out 3A DC-DC Digital Control Step-down Module Adjustable buck converter B3603 #ARDUINO http://www.ebay.com/itm/3A-DC-DC-Digital-Control-Step-down-Module-Adjustable-buck-converter-B3603-/171417756516?roken=cUgayN&soutkn=l5hYFI via @eBay http://www.banggood.com/B3603-Precision-CNC-DC-DC-Digital-Buck-Module-Constant-Voltage-Current-p-946751.html?utm_source=youtube&utm_medium=youtube_direct&utm_campaign=JulianIlett&utm_content=sami
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Text Comments (96)
CrankyCoder (1 month ago)
any recommendations on the best way to set the current on a CC CV buck converter that doesn't have a screen? voltage is easy. what do you recommend for current?
Vasanth Rao (2 months ago)
Hi sir will you help in Design of high Gain DC DC converter for Photovoltaic systems.
Sinisa Culic (6 months ago)
can you somehow controll this buck with an adruino or rosbery?
Viktor Božičević (1 year ago)
Hi Julian, I have this Boost Buck Converter http://www.ebay.com/itm/DC-DC-Automatic-Boost-Buck-Converter-5-32V-to-1-25-20V-5A-Step-up-down-Module-/181515918748?hash=item2a43311d9c:g:3AEAAOSwd4tUB~J4 that has no display, only pots for voltage and current regulation. How could I monitor the desired max. current limit on this regulator? Pls reply!
VibeX MaTxeMa (1 year ago)
Wow singularity....
SANG THONG (1 year ago)
kwxj61b (1 year ago)
Hi Julian. The module you have, can it have it setup to automatic to turn it on (without manually hitting the "OK" button) when power comes on after blackout?
Thomas Doherty (1 year ago)
could a 5 amp psu power a 15 amp buck boost up converter like this http://www.ebay.co.uk/itm/292106980871
Michael Baker (1 year ago)
nicely done! thank you for taking the time to share.
Andrei V (1 year ago)
If i power it from a 120 Ah baterry will it burn the circuit? Thank you!
Andrei V (1 year ago)
Thank you!
Mile Jukic (1 year ago)
Karim Ismail (1 year ago)
Great video Julian. I just received the A3606 module. Will connect it to my 6 caps smart plate. Easy way to adjust the current and voltage for many projects. Now it is priced $9.00 including shipping. Other higher modules I use with my 100w LED chips and it costs ~$20.00. All due to your recommendations. Thank you.
Thomas Bidinger (1 year ago)
How many watts can these handle?
Marcus Dutra (1 year ago)
It flicks because the resistance oscillate as the temperature so do as well as current flows on and off.
Bill Field (2 years ago)
Hi Julian, Just recently found your video here. I was wondering if you were going to do a rev/eng on this product, with a schematic etc... I need to build a board with 3 of these all together (3V, 5V, 12V) and need the CC and CV capabilities for each. I'm not experienced in this at all and could use a tutorial of this kind as help. Anyway, great video and information. Thanks.
Rakesh Sawant (2 years ago)
what will happened if i apply negative 12 and positive 12 from atx power supply to this buck converter
Weston Eichner (2 years ago)
I bought the dc to dc 400w boost converter and when i try to put a coiled wire across the terminals the device shorts out in its protected mode. How can i achieve making this little wire glow? Its seems so cool!
Ron Thompson (2 years ago)
You have a wonderful collection of buck converters,I like the big one because it has a fuse protection.I wish they would all come with that.great video
Laimonas Sutkus (2 years ago)
Is this converter digitally programmable ? For egzample with arduino ? If yes, could you give some documentation on this ?
kihama msangi (2 years ago)
hi mane msangi
Ello Oku (2 years ago)
How do I get it?
Karim Ismail (1 year ago)
Jonathan Overes (2 years ago)
Hi! Lovely video! Very clear and easy to follow! But I do have a question: If I want to stabilize 24v that is being produced by two lead acid battery's in series and also want the regulator to be able to handle 6 A what kind of circuit could I build in order to regulate that? I've been looking around, searching for a voltage regulator that is capable of that but none of them go to such high voltage together with such high amps. I would like to prefer using base components because although your buck converter seems to do the job perfectly, it's huge and probably expensive as well (it's a school project). Thanks!
Basavaraj Madiggond (2 years ago)
I would like to bye this kit. But shipping is not provided to India. Can you please suggest how can i get this product?
Joshua B (2 years ago)
Great video... please link where to buy the bigger boost converter please !!
Karim Ismail (1 year ago)
Similar one I found for you,15 Amp&900 watts. Link: http://m.tomtop.com/electronic-components-217/ About $20.00. Best luck.
Jon Newell (2 years ago)
Brilliant, all the info needed and then some. Thank you sir!
Vidgester1999 (2 years ago)
What happens when the input voltage is lower than the set output voltage? Does it just output the same voltage as the input? For example; If I input 12v and set my output to 10v, what would happen if my input voltage drops to 10v and then even further to 8 or 9v?
SCWfan06 (1 year ago)
Vidgester1999 Input has to be higher than output.
JasonMasters (1 year ago)
If I understand the principle correctly, the converter steps up the voltage as well as stepping it down. The only "gotcha" is that the input still has to be able to supply the required current at that lower voltage, so that the converter can boost the voltage and still supply the asked-for current.
siemon pryns (2 years ago)
I am searching for a charger to charge a 12 battery, with a wind driven(variable) dc input. sugestions? maybe this one. Thanks, greetings.
siemon pryns (2 years ago)
I am searching for a charger to charge a 12 battery, with a wind driven(variable) dc input. sugestions? maybe this one. Thanks, greetings.
JasonMasters (1 year ago)
I'd expect a simple solar charge controller to do this job, with the solar panel inputs connected to the wind generator. I wouldn't recommend one of the more complicated chargers, because the programming might expect a gradually increasing availability of power from the solar panels, which a wind generator won't normally supply.
ArcanePath360 (2 years ago)
They're effing HUGE
xxgg (3 years ago)
Question about DC Voltage Step Up converters. How much energy is lost during the conversion? (ex, 1cell 3.6v to 5v) Just saw a local news talk about portable battery packs for smartphones and they done some testing from a lab and due to loss during conversion, news say users can only expect about 70% of actual battery mAh capacity. Does this sound about correct? I mean... pretty much every portable battery packs I see either use 18650s or LiPo.
xxgg (3 years ago)
I am currently charging my iPad Air with my Anker 5400mAh pack and monitoring mAh being put into iPad.  I'll post result when it is done.
Julian Ilett (3 years ago)
+xxgg Actually it's probably worse than that. The step up converter is generally about 90% efficient, but power is also lost going into the power pack. That's because a linear regulator is used to take 5V down to 3.7V so the loss is (approximately) 3.7/5 which is about 74%. 90% x 74% is 66%.
Anthony Rutka (3 years ago)
What was the amperage of the 12v supply used?
Marcello Fialho (3 years ago)
You just put together an e-cigarette mod, haha. A DIY one. A mod is really a dc-dc converter (powered by IMR 18650 batteries, with a nominal voltage of 3.7V). The coils are either made out of Kanthal or Nickel wire (Nickel is used for temperature controlled devices). The mods have a microprocessor running a firmware and it reads the resistance of the wire and allows the user to adjust the amount of power sent to the coils in Watts or Joules. If you use 24 gauge Kanthal you will see an amazing glow in the coils and they won't burn out easily. There is a chip called the DNA 200, which is completely digitally controlled and is much smaller than this one, It comes with an LCD display, is able to read nickel wire resistance in real time and control the temperature of the wire by doing that. It is done by a US company called EVOLVE and there are many clones in China of it.
Rocco Croce (3 years ago)
If the input on the B3603 was reversed, which component(s) of the unit will need to be replaced for it to work properly again? Thanks !
MrTechguyy (3 years ago)
Can anybody give me some information on how to use the menu on this please?
Bubba (3 years ago)
Thanks for the video. I wish you would have tested the actual resistance on the big resistor to see if it was off, instead of just assuming it was the problem... it could have been the regulator. Also, I wish you would have tested the accuracy of the displayed output volts and amps vs a good meter. :). I know this wasn't a review of the product, but you went so far, that the last details would have been easy.
Virulent (3 years ago)
hi Julian, great videos. one of my favourite electrical channels on youtube ! you should have more subscribers. Thanks for the uploads.
DIYin (3 years ago)
As a beginner i love you channel and i learn so much in one video... and im intressted in getting my first buck converter, and i dont know which one i should get, as i consider myself as a "noob" i want a cheap converter that is easy to handle. thanks in advance.
Julian Ilett (3 years ago)
+Alber Ammanuel Get the B3603
danh le (3 years ago)
so there's no real difference in the b3603 vs b3008 units besides being "able" to handle a max of 8amps and the voltage differences? (and physically i see the toroid thing in the middle of the b3008)  .........so why is it like 3X THE PRICE?
Clive Flint (3 years ago)
Hi Julian, Did I read correctly that this stopped working after a few days?
Clive Flint (3 years ago)
+Julian Ilett That's good news, I thought I read that it had let out the magic smoke.
Julian Ilett (3 years ago)
+Clive Flint Er no, mine is still OK
Nimbusalliance (3 years ago)
Thanks Julian for all your videos, I'm learning a lot from them!!! Having bought a B3603 (and loving it), I wonder why I can't find any AC to DC adjustable converters/regulators, as I'm hoping to do away with AC/DC transformers in a live setup....
dco dco (4 years ago)
This is such a great hands-on example.  You see so little of this in general, even on YouTube.  Thank you for taking the time and doing very clear and professional work!
Julian Ilett (4 years ago)
+dco dco Thanks for the comment  - much appreciated
The Lightning Stalker (4 years ago)
Have you tried the 12A buck regulators?  Are they any good?
Shaun Dobbie (4 years ago)
Are you getting much power from your panels at this time of year? My 800w array is giving me 0 watts during the day at times.
Shaun Dobbie (4 years ago)
Me too, all I can have running at the moment is an IP camera and a raspberry pi all running on a 24v 225ah battery bank which I have to charge every day or so from mains electricity. How I hate Winter.
Julian Ilett (4 years ago)
+Shaun Dobbie I have to be careful - not draw too much from the batteries this time of year.
Özay Turay (4 years ago)
Hi Julian, alice1101983 is selling something you might want to test/use, and it's cheap as always. ;) http://www.ebay.com/itm/USB-Load-resistorPower-Resistors-Mobile-Power-Aging-Resistance-module-1A-2A-/311167845560 I love your videos, keep up the good work. Cheers. :)
quaxk (4 years ago)
a DC DC converter makes a rather noisy bench PSU, even if you add a low pass filter you still gonna get nasty ripples, good enough for LEDs I guess, but nothing sophisticated
Alex Turcu (4 years ago)
Question: What's the minimum difference between the input & output voltages? Alternatively, for a particular Vin (say 12.6V from a SLA battery), what's the maximum Vout I could get out of it?
Julian Ilett (4 years ago)
+Alex Turcu Probably not much more than a diode volt drop - in other words, a volt or so.
oreubens (4 years ago)
Question:  With the single wire strand. It was giving you 3A and low voltage. Is that a restriction of the converter circuitry, or is that caused by the fact that the input (lead acid batteries) can't provide enough input power for the converter to get the voltage up as well ?
Julian Ilett (4 years ago)
No, it's simple ohm's law V=IR. The wire strand had a resistance of 0.25 ohms. Multiply that by 3 amps and you get 0.75 volts.
oreubens (4 years ago)
9:48 And you have just made up another (extremely elaborate) way to make a led flash. :-)
Julian Ilett (4 years ago)
Haha, well spotted. Every gadget must have a flashing LED.
Kieran Simkin (4 years ago)
Interesting that at the threshold current it's flicking between CC and CV at a rate of almost exactly once per second. I'd expect it to be flicking between the two at some fast rate, fast enough that they'd both appear to be on, so you would get that situation where both lights appear to be on. I'm guessing that 1 second switching period represents a 1 second hysteresis in the module's CV/CC algorithm, so it's limited to performing exactly one switch between CC and CV every second. I'd be interested to see what impact that has - if it's in CV mode and it's already done the one switch in that particular one second period, would it be possible to arrive at an over-current situation if the load resistance suddenly dropped very low?
Kieran Simkin (4 years ago)
+Julian Ilett Aah that sounds like a plausible explanation, easier to test too because you could temporarily replace the output caps with smaller ones and see if the ooscillation speed increases, or (even easier) increase the capacitance by adding more in parallel and see if the speed decreases. I'd have a go myself but I haven't got one of these devices handy - I'll likely order one when I have a bit of spare cash - being a bit of an eBay bargain hunter like yourself I often steal purchase ideas from you :)
Julian Ilett (4 years ago)
+Kieran Simkin My impression was that the slow oscillation was due to the quite large smoothing capacitors on the unit's output. This would limit the slew rate of the output voltage and therefore the current also.
Kieran Simkin (4 years ago)
On further contemplation I don't think there can be a one second hysteresis in the CV/CC algorithm because it just wouldn't work properly if there was. Perhaps the hysteresis is just on the output to the lights? With a bit of fiddling is it possible to get it to switch between CV and CC at a faster rate? I'd be interesting to see some further inspection on this - you'd need to trace out the V and I curves on a scope to get an idea what's really going on.
Tradie Trev (4 years ago)
Popped it! Yeah I'm all for blowing stuff up!
Craig Overend (4 years ago)
You should start a channel called: "Will it CV or CC?" I enjoyed that. :) There is certainly the accuracy of the 10W resistor to consider, however the temperature coefficient of the 10W resistor should also be considered among other things like the accuracy of the voltage and current reading of the Buck Converter itself. In a perfect world I'd expect the CV and CC to oscillate, which I find interesting to think about...
Tiit Saul (4 years ago)
Good video. I just blew one of these up last night.
Simon Parkinson (4 years ago)
I've made a little bench power supply using the B3603 and a 19V laptop charger. It's housed in an old CB-radio power pack case. Slight drawback is that the output negative is directly connected to mains earth, but the unit can be powered through the bench isolating transformer if needed. The tiny heatsink provided proved inadequate at 12V 2A, luckily it's quite easy to graft a better one on. It works very well, though I haven't measured ripple and noise. It's also nice to be able to set the current limit before you start. My BK Precision 1550 (38V 3A) Bench PSU doesn't do that - annoyingly you have to set a low voltage, short the outputs and switch on to set the current limit. That's stupid! If the tests are good re ripple and noise, I might make a triple-output supply. Conventional 50Hz transformers though, making the outputs isolated from mains earth. A little bit of hacking to make a tracking split supply from one controller would be cool.... another one to add to my long list of projects lol! I've also used one of these as a charge controller for my daughter's motorised trike. I got it second-hand, the battery (6V 10Ah SLA) was past its best. Got a new battery but soon found that wouldn't have lasted too long either as the original charger was seriously overcharging it. Set at 6.9V with a 1A current limit the unit barely gets warm. I'm using a 12V 2A mains adaptor. Current drops to the region of 4-7mA depending on temperature when fully charged. I do intend to fit one of the more basic twin-pot regulators to free up that B3603, though I have 3 more lying around. One thing to note though - the whole unit powers up when connecting the battery. I didn't want to add a diode as regulation would suffer. Final version will include a relay to prevent this. The heatsinking on the B3008 seems a little better, but I'd be tempted to bolt the devices to a much larger heatsink if I used one for something permanent. Simon.
Lance Guilin (4 years ago)
+Julian Ilett I kept unit at 2A max. stilled started malfunctioning after a few days of use. 
Julian Ilett (4 years ago)
+Simon Parkinson The B3603 is an excellent little converter, but these Chinese modules should always be de-rated - 2A sounds about right. I think there's a P-channel MOSFET circuit that you could use to prevent the battery on the output from powering the circuit
Robert Cookson (4 years ago)
GREAT explanation with a very easy to follow demo. Now it makes sense on how the two do there function and why its mostly one or the other from the supply. 
W Boumans (4 years ago)
Good video. I might pick one of these up on Ebay :)
Michael Walker (4 years ago)
Found this one, allegedly UK location but we'll see... :) http://www.ebay.co.uk/itm/B3603-Digital-controlled-Current-Voltage-DC-Step-Down-LED-Driver-Power-Module-/291225168644
Neil Perry (4 years ago)
Is that UART to the left of the top board? Does that allow for remote setup?
Neil Perry (4 years ago)
Shame that could have been useful for an arduino based charge controler
Julian Ilett (4 years ago)
+Neil Perry In theory, but it doesn't appear to be implemented. Shame.
Dobrica Pavlinušić (4 years ago)
Julian, I can see that you have four pin header soldered on the board. Do you have any info about it? I would love to drive it with something other than buttons...
nasrin banu (2 years ago)
nasrin banu (2 years ago)
+Julian Ilett Hola jhuuu788
+Julian Ilett Thanks for sharing. I have the B3603 with the 4pins labeled, from top to bottom, Vcc TxD Gnd RxD.
Julian Ilett (4 years ago)
+Dobrica Pavlinušić I've just put a photo of the Communication protocol on my Facebook page: https://www.facebook.com/pages/Julian-Ilett-on-YouTube/743713062366989
Dobrica Pavlinušić (4 years ago)
+Julian Ilett ZXY6005 control board looks different to me than this one. however, this one also has additional four pins next to buttons, and I would guess that those are programming header for ST8. I would also love to find document about serial protocol, or at least have idea of at least one command. I'm interested in driving B3603, but control boards looks same so that's why I was asking this question at the first place.
Eqvaliser (4 years ago)
Interesting, I'm working on a home automation for my greenhouse using arduino for control and a car battery for power. Was planning on using a linary voltage regulator for the 5v to the arduino, reason for the car battery is because window servo is a 12v also my water pump is 12v. but I doubt an arduino would be happy with 12v for a longer period. Any suggestions about voltage regulation on Car battery(12V) > Arduino(5V)? btw. I'm charing the battery on sunpower, with a 12v controller.  So no sudden spikes of power like with an alternator.
Eqvaliser (4 years ago)
An update,, I got a 15v -> 5v Buck down converter, and it works like a charm.. Thanks for the tip.
Eqvaliser (4 years ago)
Thank you, will look into this   Good video ;)
Julian Ilett (4 years ago)
+Eqvaliser If you're using solar power, use a DC/DC buck converter for your 12v to 5v conversion - it's more energy efficient than a linear regulator. You won't have any issues with switching noise - the Arduino, pumps and servos are all pretty noisy themselves.
area46241 (4 years ago)
Most excellent!

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