Background

Parallel Port Interface


During my high school years I took a robotics class, my teacher, Jim Fuller saw that I had an excellent grasp of electronics and computing, and when I requested to build a parallel port interface based on his design that he used for his classes, he was rather generous and provided me with one of the pre-fabricated Printed Circuit Boards, all I had to do was supply my own parts, which I scavenged from old discarded ISA expansion cards.

The design provides 4 Relay switched outputs with status LEDs, 4 switchable LEDs, and 4 binary inputs.

I did make one minor improvement to his design, I added an inverter to one of the inputs that gets inverted on the parallel port, meaning that it would behave like all the other inputs.
I also used a regulated DC power supply "brick" from an old laptop that outputted the 12 Volts needed, rather than an unregulated power supply and having to use a rectifier, regulator and filtering capacitors on the circuit board.

Picture

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