Sunday, November 18, 2012

Tiny Power Supplies for Micro Controller Projects

When you build micro controller projects, eventually you want to do something real that will have to work long term.  For this you need a power supply that is small, maybe small enough to put in a light switch, ceiling fan, or dryer control panel.  These things are hard to find.  I've spent hours on Google trying to find really small 5V supplies with some success, but never fitting my needs.  Nice little supplies that you have to buy in 100+ quantities, nice little supplies that cost US $50, etc are out there, but who wants to invest that kind of money in a technology that changes almost daily?

In a few project postings I describe how I cut the guts out of a wall wart like this:
These little devices work great as microcontroller power supplies.  The one above will put out up to 2A and doesn't seem to get hot doing it.  I've had several in service, out in the weather for two years.  At a cost less than US $5 each (usually with free shipping) they are a fine solution.  I've taken the supply out of the plastic case and installed it into devices like this <link>:
The little board in the upper left is the guts of the wall wart.  I've even used the entire wall wart as a mounting platform for another device:
This device <link> has an XBee mounted on the side of the wall wart transmitting temperature every minute or so.  All-in-all, a pretty useful device repurposed from the iPad craze.  However, technology moves on and I want to try a couple of ideas that would work better if I had an even smaller power supply.  I asked on a couple of forums and was pointed to one of these:
I already had two of them charging mobile devices in the house so I decided to gut one of them and see what was inside:
This little supply is TINY. Yes, I had to cut the case off with a Dremel to get to the guts; the top was seriously glued to the bottom and refused to come off. The two board with connecting cable configuration could create a problem mounting, but nothing I can't overcome, and the wires to the AC pins might give me a problem, but it couldn't be too hard to solve; I like this.  So, looking around the web to see what kind of deal I could get on them I found them for US $1 on Amazon.  Yes, you read that right, a single dollar, with free shipping.  So:
Here's my pile of stock devices.  

Since supply and demand act on everything, the price at Amazon has gone up to US $1.45 as of this writing and could go either up or down based on activity, but they are still a bargain.  

Even with this solution available, I'm still searching for possibilities.  The rough requirements for the supply are: minuscule size, 5V at a least an amp (relays, you know), easy to mount, things like that.  

To you suppliers out there, there's a market here that you aren't exploiting.  SparkFun, Lady Ada, Itead, etc. are you listening?  You folks in China, what are you waiting for?


  1. This Tiny Power Supplies for Micro Controller Projects is very crucial projects and hopefully such crucial projects are sound wonderful for continuing power supplies. Thanks

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