Review: Mini 3A Voltage Regulator (4.5V-28V to 0.8V-20V)

by Oscar

I’ve been using this little step-down voltage regulator for years, and I absolutely love it! It’s cheap, small, light weight and capable of converting 4.5V-28V (2S to 6S) to 0.8V-20V (1S to 4S). You can adjust the output voltage by turning the knob, which is really convenient.

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Where to Buy?

Get this mini voltage regulator from these vendors:


  • Input voltage: 4.5-28V (2S to 6S)
  • Output Voltage: 0.8-20V (adjustable)
  • Max output current: 3A
  • Switching Frequency: 1MHz
  • Output Ripple:less than 30mV
  • Efficiency:96%(max)
  • Operating temperature: Industrial grade (-40 C to +85 C)
  • Module Properties: Non-isolated step-down module (buck)
  • Size:22*17*4mm (size of a coin)
  • Weight: 2g

3A-mini-back 3A-mini

It’s tiny and light weight, which is useful for FPV drones and RC planes, it’s also handy to have for electronic projects. It supports a wide range of input voltage from 5V, or 2S all the way up to 6S, and the output is adjustable using a screw driver (you also need a multimeter to verify the output voltage).

Although it’s rated for 3A, I would not recommend using it for anything above 2A without a heatsink and decent cooling from airflow. From my experience, at 1.5A, it can get very warm.

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Jesse 4th April 2022 - 9:16 am

Great info but I’m having trouble finding any info on the 600 tvl cam any brand and what or how to fix when the wires come off… I can’t find any positive or negative marks, so frustrating… Any help would be greatly appreciated….

stev 7th December 2016 - 2:26 am

1. Would you post the assignments of the 8 connections?
2. Nice inclusion of the JS requirement, a relief to see.

Callum 22nd February 2016 - 10:52 am

Hi Oscar, I purchased a few of these recently but I am struggling to get them to do their job.

I wired them up like this Just confirming all I have to do to change voltage is to screw the screw left or right?

My wiring is exactly the same as rcmodelreviews (the same as rcmodelreviews review video, I don’t have a pic of my own on hand right now.)

When I plug it in I measure 12.4v (straight battery voltage) coming out.

When I turn the screw I have zero change in voltage.

What am I doing wrong? Frustrated to be stuck on what seems like such a simple part of this build.

Oscar 22nd February 2016 - 12:10 pm

are they behaving all the same? if just 1 then i would say might be a faulty knob…
but if it’s happening to all, then it’s probably how you turn them? or just they have a defective batch?
i have used more than 10 of these and i have never seen this problem myself

by the way, I recommend joining this forum, it’s very useful and there are lots of helpful people there. I am a daily user too :)

Callum 22nd February 2016 - 8:01 pm

Hi Oscar, thanks for your reply.

I bought 3 and have tested 2 so far. All I have to do is turn that big outer screw right?

I contacted the seller and they told me to use a very small screwdriver to turn the inner screw?????

I will join that forum you mentioned, thank you!

Oscar 7th March 2016 - 2:23 pm

yes by turning that little pot (screw), you can adjust the output voltage.

jeff 25th May 2016 - 7:42 pm

Do you have the output / input reversed? … cause mine did the same thing until I realized I wired it backwards, lol!

Additionally, these regulators put out decent current … I am running 4 Mobius boards off one of these units … I did mount it externally so prop air will cool it.

max 24th December 2015 - 3:19 pm

hi oscar,

i also discovered this regulator as well and picked one up.
i hooked it up to my multimeter and the 12 volt rail of an old pc psu. when i turn the potmeter the output voltage’s range is only 0.8 to 1v, way of the desired 5v.

now i am wondering how you were able to get a voltage of 5v out of it.


Oscar 25th December 2015 - 8:21 pm

there is a knob you can turn with a screw driver to adjust the output.

Alexandru 21st September 2015 - 8:50 pm

What if to use an UBEC 12V instead of LC filter + Voltage Regulator? As I know LC filter, filters noise coming from ESCs. I’m not sure for 100%, but I think OPTO ESCs don’t make noise. So just a voltage regulator should be fine. And I was wondering if I will use an UBEC for FPV instead of voltage regulator. That will give me filtered 12V… Isn’t it?

Oscar 22nd September 2015 - 11:09 am

HI Alexandru, that’s a very idea, I will look around for a light weight 12V UBEC and test it :)
But i think LC filter is still required possibly at the UBEC output

mathew t 31st January 2015 - 10:34 am

Another excellent post answer yet another question I had!
Keep it up mate.

Tunedis95 9th October 2014 - 2:27 pm

Great blog and very informative just as everyone else said. Kuddos! Building my first quad following your blogs.

Question, how do you adjust the output on this voltage regulator? Use a phillips to turn that “screw”. Moniter with a voltmeter on the output side as adjusting? Just trying to be crystal clear.

Thanks again for all your time and effort, hope to do my part with my build and help others too.

Oscar 9th October 2014 - 3:58 pm

Glad you enjoy it! :D
Yes, you are correct.
There is a knob you can turn to adjust the output voltage, using a philips.
connect the output to a voltmeter, or a multimeter, to monitor the voltage.
Make sure you wrap the regulator with heatshrink or something similar, just to avoid the output voltage get accidentally changed.

Tunedis95 11th October 2014 - 9:43 pm

Ahhhh. Good words of wisdom. As far as the rest of the electrical components, I will be applying a clear Urethane Seal Coat to prevent any shortages from blades of grass and what not. I was Planning on spraying this regulator too. Spray alone i’m sure will keep adjustment screw in place.

Oscar 13th October 2014 - 12:41 pm

that is a very good idea! I would have done that to mine if I have got the spray!

Colin Conway 23rd September 2014 - 2:47 pm


Great site by the way, a wealth of knowledge here. I’ve built two quads since reading your blog, both working excellently.

Quick question for you, what order is best for the voltage regulator and power filter? I presume your battery is connected to the regulator and the power filter wired next and then your fpv camera system???

Oscar 23rd September 2014 - 3:08 pm

Hi Colin, that’s what I always like to hear :D

I prefer to place the filter before the voltage regulator, because when power filter (LC filter) is removing noise, you will see a voltage drop at the output of the filter, but the voltage regulator would not mind the drop, and will still output the desired voltage (or close enough). But if you have them the other way round, the voltage drop could be noticeable and it might upset the devices you are running on your regulated voltage.

Apart from this, there are also performance concerns (noise-removing result) that suggests LC filter should be placed before the regulator. But I am not familiar with this myself.

Colin Conway 24th September 2014 - 1:45 pm

Excellent. Thanks a million. Hooking up my FPV system to a 4S battery today so hopefully it works out alright.

Tony 13th August 2014 - 3:06 pm

Thanks for the interesting article. I have a few questions. Except being cheaper, how is this device different from a bec? Is it a switching regulator versus a linear regulator? In the photo showing the heat sinks, it looks like a different board (perhaps a higher resolution resistor for setting the voltage?) . I guess it is the one from this page: What is the difference between the two devices?

On the device pictured on this page, which component would you add a heat sink to?


Oscar 13th August 2014 - 5:24 pm

A few reasons:
– cheap (as you pointed out)
– adjustable output voltage
– wider input voltage range than a BEC
– smaller and lighter

In the post, the one with heatsink, is my old linear voltage regulator.
If you need to put a heatsink, put it on the 8 pin black chip.