Newsgroups: comp.robotics
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!newsxfer.itd.umich.edu!agate!spool.mu.edu!caen!hearst.acc.Virginia.EDU!pen.k12.va.us!fculpepp
From: fculpepp@pen.k12.va.us (Fred W. Culpepper)
Subject: Re: relay control device ?
Message-ID: <DBHC64.1HCC@pen.k12.va.us>
Date: Mon, 10 Jul 1995 02:56:28 GMT
References: <1995Jul5.171732.2462@alpha.nsula.edu>
Organization: Virginia's Public Education Network
Lines: 37

 (nspoo1900@alpha.nsula.edu) writes:
> This may not be a good area to post this but here goes.
> 
> I want a device that will respond to a number sent through a parallel or serial
> port and switch relays connected to this device.  I want to control devices
> from my computer.  If I can switch relays I am home free.
> 
> 
> Thanks for any suggestions
> 
> 
> 
> Poole

If you have an Apple II (II+ or IIe or even a IIGS), you can input 
and output through the game port (16 dip socket on mother board) 
using Applesoft for programming.  Output and input terminals
are TTL compatable.


If you need source information and details, check the original
manuals that came with the computer for the topic, "Game I/O
Connector."  You will also need to check for the commands to
turn on or off the outputs (four - expandable to 16 with TTL
circuitry) or to detect the presence of an input (three -
expandable to 8).  These are generally found in manuals on
programming in Applesoft.

A power transistor or SCR can be driven through an opto-coupler
to provide control to the relays.  Currently, I am driving a
bank of 15 relays (24v. 4C) with this circuitry.  

By the way, the game port allows an input of 4 resistive or
voltage sensitive signals.  Very handy for the input of
resistive sensors.

Fred Culpepper
