As I reported in my last entry, I put together a small interface circuit to key my rig using the parallel port of my laptop computer. I built the circuit on a little piece of perfboard that fits inside the DB-25 connector shell.
The first circuit I built consisted of one resistor and and one transistor. Bending the leads on the resistor just so pretty much kept it on the board, but I had no way of affixing the transistor to the board very well. I bent the leads so they would go through the .100-in. holes and tacked the wires from the cable and the connector to the leads. That worked OK, but it really wasn’t the best solution. As luck would have it, I put the transistor in backwards and probably destroyed it when I powered up the circuit.
Before building the second circuit, I came across some adhesive-backed pads and traces that I’d purchased years and years ago. The brand name of these products is E-Z Circuit, and they were manufactured by a company called Bishop Graphics in Westlake Village, CA. These are very cool, actually, and pretty easy to use. See the photo below.
For the second circuit I built, used a 4N33 opto-isolator in a six-pin DIP package. I didn’t have any six-pin DIP sockets, but I did find an eight-pin socket. Using the pads on one of the strips that were laid out specifically for IC sockets, I cut out two strips of four pads, lined them up properly with the holes on the perf board, and pressed them onto the board. I then inserted the IC socket into the holes on the board and soldered the pins to the pads.
Connected to each of the IC socket pads is a strip of two or three more pads that you can use to the IC to other components. Using the E-Z Circuit pads, I put the thing together in about 15 minutes. Nothing needed to be tacked together, and the circuit worked right the first time.
Now the problem is that I’m running out of these pads and traces, and apparently Bishop Graphics is no longer in business. A Google search turned up only one reference to the company, and that page belongs to an idustrial electronics distributor in WI. I’ve emailed them about availability, but am not getting my hopes up.
If any of you out there know where I might be able to get more E-Z Circuit supplies or something similar, please e-mail me with the information.