Breadboard power supply
Last Sunday I woke early so I started on a project I’ve had in mind for a while but not gotten around to doing. I built a power supply module that plugs in to a breadboard. There are a few kits for these kind of things around from Adafruit and others but I had slightly different requirements.
My basic requirements were 5V and 3.3V supplies with the unregulated supply coming from a power adapter plug. I built the circuit on strip board as I had some available, it saved me designing a circuit board, and the holes lined up. The size of the board was set by the width of the breadboard together with how much of the breadboard I wanted to obscure. I also wanted indicators for the unregulated supply, the 5V supply and 3.3V supply so that I could spot any faults. And I wanted it to look relative tidy. This is what I came up with…
I kind of put the cart before the horse since I didn’t have a circuit when I started. It was built basically from a design I had in my head. Its a fairly text book design with a diode to protect the circuit from reverse current, smoothing capacitors in to the regulators and smoothing capacitors on the outputs. LEDs and current control resistors make up the rest of the circuit. The electrolytic capacitor values were basically based on what I had available. I suspect a 100uF on the input smoothing would be better. The schematic is below.
I like my electronics to look neat so I laid out the major components to ensure the board was symmetrical, the LEDs lined up and it plugged in to the breadboard without issue. Everything else was fitted around those components. There are no breaks in the tracks on this circuit although there are a couple of wires underneath to provide the GND ‘plane’.
Finally here’s a close up of the board. This is annotated on Flickr so you can see what does what.
All in all a nice way to spend a couple of hours on a Sunday.