Monday, 24 October 2016

Power Supply board, part 1

Following on from my previous post about the power supply board, I made a number of improvements to the layout since the initial design. Also I completed it by adding the bias supply components.

Confident I had something I was ready to produce, I went through the process and learning curve of making a PCB. This resulted in some difficulty transferring the design successfully from the plastic film it was printed on, to the board ready to etch.

However a few trials and errors and finally I had this ready to start stuffing, after carefully etching and drilling:

Ain't it beautiful?

The first usable PCB I ever made, or at least, almost usable... 

On this board is a galactically stupid n00b mistake which renders it completely useless: I'd neglected to mirror-image the pinout of the 555 IC I'm using as a start-delay. So in order to get this working I'd need to mount the IC to the underside (ie. solder-side) of the board.

Not happy with that at all. 

So I've corrected the design and it's back to the electronics shop, can't go tomorrow as it's a public holiday, so now need to curse my naivety until Tuesday when I can get another board and transfer the design onto it one more time...

THEN I will have a power supply board that works...

However this experience has taught me a few useful things. Firstly, the heat transfer method of getting an image from a laser printer onto a board is a bit hit-and-miss, but I found polishing the board with Brasso first then roughing it up with steel wool helped.

Secondly, despite this board having 110 holes (or thereabouts) the drilling process did not take long, the drill stand makes it easy.

Thirdly, sharpies are magic for filling little holes in the resist prior to etching the board.

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