The D25 Plug

You will be using only a limited number of connections to the D25. But to get a secure mating with the computer you really have to use the full plug.

I used a nine strand ribbon cable rather than a full width one.

Take the cable lines. Start at the red-striped line on one of the edges. Number it 1. Carefully break the line from the rest of the cable for a length of about 3 inches. Make the next line 2 and strip it out in the same way. Call the third line 15 and strip it out and the fourth 12 and strip it out. Go to the other end of the cable and strip the last line out and number it 18. (Picture)

Now snip off the unused lines back at the 3 inch point.

Next strip back a half an inch of the plastic cover of each line. Be careful because it is easy to cut the strands of the wire .  If you don’t usually do this type of cable stripping, then practice.

Solder the lines as numbered onto the D25 plug.

The Circuit Board

The circuit board is dead easy.

Start with the transistor. Place its legs through the top of the VeroBoard as shown in the diagram, Push them through about 0.5. Bend the legs out a small amount so that the transistor doesn’t fall out when you turn the board over.

Quickly tin each leg and then apply solder so that each one joins onto the its copper strip. Do not leave the iron in contact with a leg for more than couple of seconds. Transistors can be cooked - then they don’t work.

Next, put in the resistor and bend its legs. Tin and solder.

Now take each length of wire you have prepared. Twist the wire on the stripped ends and tin. Following the sequence on the diagram, insert each wire and solder it to its copper track.

Take the other end of the D25 cable. Break out each line you will be using and follow the same procedure as you did for the plug end, snipping off the unused lines. Now insert each of the lines into the appropriate hole on the VeroBoard (see the diagram) and solder to the copper strip.