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

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.

Where to Buy?


  • Input voltage: 4.5-28V
  • Output Voltage: 0.8-20V (adjustable)
  • Output current: rated current 3A (MAX).
  • 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 not only useful for multirotors and RC planes, it’s also been extremely handy for some of my electronic projects as well.

Although it’s rated for 3A, I would not recommend using it for anything above 2A without a heatsink. From my experience, at 1.5A, it’s already getting very warm.

20 thoughts on “Review: Tiny 3A Voltage Regulator (4.5V-28V to 0.8V-20V)

  1. Callum

    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.

    1. Oscar Post author

      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 :)

      1. Callum

        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!

    2. jeff

      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.

  2. max

    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.


  3. Alexandru

    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?

    1. Oscar Post author

      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

  4. Tunedis95

    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.

    1. Oscar Post author

      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.

      1. Tunedis95

        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.

  5. Colin Conway


    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???

    1. Oscar Post author

      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.

      1. Colin Conway

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

  6. Tony

    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?


    1. Oscar Post author

      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.


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