I always wanted an adjustable Power Supply that would shell out about 1-1.5A for most of my applications as a hobbyist. But the Space they occupy and the price they come with are always a problem. So, I thought of building a very small power supply that would serve my purpose.
Having worked with LM317 earlier , i choose to build my around it. LM317 can give out about 1.5A according to the datasheets which is more than enough for most of my applications. Now the next hurdle was to make it as small as possible. The schematic is given below:
It took a couple of design iterations to make it suitable for a single sided board and i was finally able to come up with a very small one.
The size i was able to build was 3cm X 2.5cm with all components included on board.
Before making(etching,soldering) it was necessary for me to do some 3D- Rendering of the PCB so that i can have a better Idea of how the final board will look. I used Google SketchUp for the same. The Isometric image is provided below:
It took me a while to make the board as the Bourns Pot i had was faulty and the local store took some time to get it for me.The board has a heat-sink for LM317 glued using processor heat glue to dissipate heat.There is also a small switch that i managed to squeeze on the board and a diode..just in case you had polarity issues.
The completed board that i built looked like this:
This is the demo picture showing the output as 2.9V at a 8V input from a standard AC adapter.
Cheers and Regards,