Interfacing to AC; lamps, relays

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Davetracer@xxxxxxx 


    I would like to ask for some help in interfacing a 
microprocessor to some unusual parts. Well, unusual for me, anyway.

    I was very impressed with the "singing Tesla coil". I would like 
to try a few things along this line.

    What I would like to do is interface an 8255 PPI chips 
(essentially, three 8 bit I/O ports, programmable) to several things:

    A: 24 volt AC relays. I am especially concerned about the 
inductive "kick" that's going to happen when an energized relay 
opens. (If necessary I can set these up for DC, but I happen to have 
a lot of these relays at this voltage).

    B: 6 volt incandescent light bulbs (e.g., pretty much flashlight bulbs).

    I could (and probably should) change these out for LED's.

    I need to go both ways; e.g., turn on the relay, and also sense 
whether or not it is on. Same for the light bulb; turn it on, and 
also sense if it is on.

    I'm thinking that perhaps optocouplers might be a good idea.

    If there is good information online, I'd appreciate you pointing 
me to it!

    Thank you,

    Dave Small

p.s. Whatever we do, I'm going to have to repeat it 24 times per 8255 
chip, and there will be several 8255's, so hopefully it'll be nice, 
simple, and very robust.