Control 8 Electrical Devices With Your Parallel Port

Michael Williamson writes "A PC parallel port can provide 0 or 5v on 8 pins, individually controllable. This can be used to directly drive LED lights, or with the addition of an external power supply, some switching transistors, and some relays, control 8 higher-powered devices. I've written a handful of example programs that drive a homemade 8-LED display in amusing ways."

Comments

I've just built something like this

[skinfitz]

I got a relay kit from Carl's Electronics which switches 8 relays and works brilliantly. Great fun!

Nice coding, Tex

[ObviousGuy]

value = pin[0]*1 + pin[1]*2 + pin[2]*4 + pin[3]*8 + pin[4]*16 + pin[5]*32 + pin[6]*64 + pin[7]*128;

And they say Perl looks like line noise.

Re:Is this a slashdot story?

[Mr. Slippery]

Yes, it is a good /. story.

Believe it or not, there are geeks who've lived only in the software world, and never even picked up a soldering iron (sad but true), but would like to learn a little. A simple electronics project that gives them a taste of the hardware world is just perfect for them.