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Step 2Making the Circuit Board
Take the 22 x 12 stripboard, mark and cut as shown. To cut stripboard, score it deeply with a craft knife (using a ruler) on both sides. Then use a pair of pliers to very gently flex it. The board should weaken and break. Later on I accidentally broke off the thin leg so substituted a brass pin and used this to connect the -ve battery terminal.
This layout developed as I built it, so look at the front and back photos to get the component and cut track locations. A spot face cutter is the best tool, but failing that, use a handheld 5mm (1/4") drill bit or a craft knife. Make sure no thin bridges of track are left.
Put in the programming socket and links first, then the resistors and finally the diodes and IC. Normally I'd use an IC socket, but there's no room for such luxuries here - The sounder wouldn't fit! Trim off anything sticking out the back of the board to reduce height. I did say this was tight!
Because we're not using an I.C socket be very careful when soldering the chip. Solder each pin for the shortest possible time to get a good joint, and let the chip cool down between pins.
For the piezo mounting posts I used brass pins from a wire-wrap IC socket, but any stiff solderable wire would do. Use two pieces (approx 8mm) soldered into the board for the posts the piezo sounder will sit on. Once soldered, bulk them out a bit with heat-shrink. Cut 2 lengths from the biro spring so that when you sit the sounder on the posts and slide the PCB into the box, the sounder is sprung against the top.
I've used the 'repair' brass wire to connect another stiff wire to and solder to the -ve of the battery. This holds the battery reasonably firmly in place. The terminals are easy to solder to, but do it quickly so as not to overheat the battery. Leave the wire from the positive terminal unconnected at the moment, until we're ready to put the whole thing together.
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Look at the 3rd picture in step 2 showing the back of the board. The socket is in the top right . The top 2 are linked and the bottom 2 are linked. The tracks connect to the rest of the circuit. Relate the top side photo to the bottom side and the circuit diagram to see where.