I want to have an as-compact-as-possible (but no limit on size) power brick/supply that takes power from a UK Wall socket and has multiple outputs with different voltages. Need 12V@2A for stepper motors, 5V@500mA for the arduino and 3.3V@300mA for some LED's.

What would be the best way to go about this? I don't need specific part numbers or anything, just the main concept so I can research what bits I need and build it. Any videos or documentation on such a thing would be great.

It's something I will probably need to mass produce (about 10 of them for all of my different projects) since I am doing the minimized version of the Arduino UNO (without the board, just the ATMEGA328P microprocessor bare.


closed as unclear what you're asking by Andy aka, Daniel Grillo, PeterJ, nidhin, Dave Tweed Jan 12 '16 at 17:30

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    \$\begingroup\$ Can you tell us what research or effort you have already made? Give us a starting point where you are at. \$\endgroup\$ – Marla Jan 7 '16 at 13:09
  • \$\begingroup\$ You haven't included perhaps the most important criterion: How much current does each rail require? \$\endgroup\$ – CharlieHanson Jan 7 '16 at 13:11
  • \$\begingroup\$ [1] I'm hoping to get a starting point from here, since all the resources I found always tend to either use something they already have and I don't, or show a variable voltage power supply with a potentiometer which doesn't suit my simultaneous multi-voltage need. [2] I knew someone was going to ask this! I think it'd be out of the scope of this question since I want to know the base concept of the solution - like - "You'd need a transformer + regulator setup or something high level like that. To answer your question, 12V@2A, 5V@500mA, 3.3@300mA \$\endgroup\$ – Pasha Siraja Jan 7 '16 at 13:23
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    \$\begingroup\$ Compact as possible but no limit on size? Aren't those contradictory? \$\endgroup\$ – DoxyLover Jan 7 '16 at 13:23
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    \$\begingroup\$ The chances are that the simplest option would be to buy a ready-made 12V adaptor, then make up a small box with regulators to drop the voltage down to 5V and 3.3V. By buying the 12V adaptor, you can get one that's CE marked for safety. \$\endgroup\$ – Simon B Jan 7 '16 at 13:27

First thought was a re-purposed PC power supply, but that may not suit your size requirements.

  • \$\begingroup\$ How about an ATX power supply intended for Mini-ITX cases. There are smaller. In any case, an ATX supply is probably the best bet for a novice. \$\endgroup\$ – DoxyLover Jan 7 '16 at 13:26
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    \$\begingroup\$ e.g. linitx.com/product/minibox-12v-80w-picopsu80/… which will give you the lower voltages from 12V. Then add a laptop power brick for 12V at, say >3A to connect to the mains. \$\endgroup\$ – pjc50 Jan 7 '16 at 13:31
  • \$\begingroup\$ Well the problem with that would be - I will be paying the price for the labour/industry/factory work gone into the device, and the brand etc. I'd much rather build something myself - smaller, while learning about how to best do it! \$\endgroup\$ – Pasha Siraja Jan 7 '16 at 13:32
  • \$\begingroup\$ Sure, although it will be more expensive to build your own. I strongly advise you take the mains -> 12V route through an external brick for safety, then build some buck converters for the 5V and 3.3V outputs (powered by the 12V input). \$\endgroup\$ – pjc50 Jan 7 '16 at 13:35
  • \$\begingroup\$ @pjc50 Yes absolutely, I will definitely use something CE to go from the wall to 12V. It's the remaining part that I haven't figured out yet - Regulators or Bucks or a combo of 12V>5V Buck then a 5V-3.3V Regulator. Hopefully the CE mark will be real CE and not China Export :P \$\endgroup\$ – Pasha Siraja Jan 7 '16 at 13:41

There are many energy efficient solutions available but since you have mentioned that you are a noob, I'll try to provide an easy solution which won't be energy efficient but should work fine for your project.

Step 1: Get a 220V to 12V wall adapter. Choose a current rating to suit your requirements. Most of the current will go in DC motors unless you have a long LED strip tied to your project.

Step 2: Decide whether you are going to use an off the shelf arduino or you are going to make one yourself. If it's a ready made material, then there is a DC jack where you can plug in 12V directly to power up the arduino. Problem solved. If you are rolling your own arduino using atmega IC, then use 7805 IC to get the power required to run your micro controller. Usually arduino consumes very low current and thus you should be fine with a linear power supply without heat sink. But if it's really going to consume 500 mA, better add a suitable heat sink to the 7805 IC.

Step 3: Most likely the LED should work with 5V or 12V. You might have to change the series resistor. Till date I haven't seen an LED which works on 3.3V but not from 5V or 12V. (Please provide the link.) I'd suggest you to wire up the LEDs on 12V line with suitable resistors and use a transistor to turn them ON using arduino GPIO pin.

However if you are sure that you can't make it work using 3.3V, then you can use a similar solution as in step 2. Get a linear regulator for 3.3V and power the LEDs using its output. you can use LM1117-3.3V for this purpose. And yes, a heat sink too.

Here is another answer I provided to a similar question. This requires a little knowledge to implement but you should know the better ways of doing things.


I have a product which has exactly this requirement and I used an AP5004 buck regulator to produce 5V from 12V, and an AP1117D33G linear regulator to produce the 3.3V


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