How Do I Power My Finished Circuit? Here's the Fix! Just Plug It in !!

About: Just getting into the microcontroller craze. I used to do this sort of thing building circuits for 8 bit microprocessors back in the early 80s, so this is kind of like reliving a bit of my childhood. Back th...

OK - so you've moved your project to a perfboard or you're designing a PC board for it.
The question is - what's a cheap and easy way to power it?
Well, we are familiar with the wall warts, but they are often bulky, and not always convenient.
Yes, you can use an iPhone charger, but the USB cord comes out too easy, plus you may want to market your device, and although that solution works great for you, it's a bit cheesy for anything other than an iPod or iPhone.

Well, Recom has the RAC02 series of voltage converters.
They will take an input of 70 to 277 volts AC in, and give you a constant DC output.
You can choose your converter to suit your needs.
Output voltages available are 3.3, 5, 12, 15 and 24 volts.

This means that once your PC Board is made and in a project box, you can have just a standard plug and cord going to it.
And the devices are about the size of a small relay, so they are easily mounted and hookup is a breeze - it's just AC in, and DC out.
One component, job done!

I have included a photo of my driver board from my LED Cube. It's a bit of a different design than you will see on the internet because I put all the driver I/O on the one board, including the transistors and 3 to 8 line demultiplexer. I wanted it set up so any microcontroller board could be easily interfaced to it, be it the Atmega32A, Arduino, Launch pad, or whatever.Also it can be disconnected from the cube so that it can be used for other projects where you just need a huge number of outputs..

With this module supplying the power to the board, I can send 5V back to the controller (whatever it is) so the entire project can be powered from it.

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    10 Discussions

    Ya. Unfortunately, my LED cube project draws about 650ma when it's got all the layers full, so it's not good for that. So I wound up getting a bunch of those iPod chargers and using those for most of my circuits. But these things are great for a nice sealed on board supply that isolates your precious circuit from the AC coming in.


    5 years ago on Introduction

    WOW! just checkin' it out looks like this could also be an awesome / useful device to use with generated power ie: wind turbines as the power coming off those are AC!

    Very nice SuperT

    1 reply

    6 years ago on Introduction

    May be just the thing for some projects. In a nutshell the device is a 65-77% efficient 1 or 2 watt switching supply able to provide up to 400 ma for the 5v version for about $16.

    Thanks for sharing.

    2 replies

    Reply 6 years ago on Introduction

    Yes, 400mA is about the limit at 5V which is the most you should put through the regulator on an arduino without a heatsink on the 1117-5 regulator anyway.

    P=IE and these devices are pretty consistently 2 Watts handling capability.
    Don't think getting the 12V module and regulating it will get you more power, because the 12V module only handles up to 167mA which guessed it...2W. If you regulate it down to 5V, you'll still get 400mA minus losses for the regulator. LOL. However, they should be able to handle just about any project I've seen hooked up to the Arduino, and certainly any project powered by the Arduino.

    A further point I would like to make here - in a project such as the PONG CLOCK - use the recom to power the LED MATRICES and the arduino can power itself off the 5V from there. If you were to power the arduino through the power input jack, and then have the arduino power the LEDs, you will heat up and (without a heat sink) possibly damage the regulator on the Arduino. This saves that worry.


    6 years ago on Introduction

    Please read the datasheet first (always good advice) if using on 230v, this REQUIRES a specific MOV fitted across the input, presumably the size of spikes available on a 230v input could damage the module, whereas 110v would be fine? Also, 1A Slow Blow fuse in series.

    So, yeah, that's three components now. But still very nice. And isolated too, unlike some supplies that hang off the AC Mains to give +5v (with bonus possibility of death through gefingerpoken).

    1 reply

    Reply 6 years ago on Introduction

    Good point, I didn't think of that since I am in North America and don't deal with 230V.
    For those that don't know what an MOV is, it's the AC equivalent of a Zener diode.
    The Metal Oxide Varistor (MOV) is a voltage-dependent resistor applied in shunt across the circuit to be protected. The RAO02 has a maximum input of 277V, so where most spikes or surges on a 100-130V line won't go near this, on a 230V input, it's a definite possibility.
    Much like a Zener diode in a DC circuit, Until its voltage threshold is reached, the MOV acts like a high value resistor, carrying a small leakage current. When the threshold voltage is reached or exceeded, however, the MOV changes state to become a low value resistor, thereby limiting or "clamping" the voltage to the threshold value plus some additional IR drop through the MOV body. If too much current goes through the MOV, then the fuse blows, protecting the supply, and by extension, your circuit.