(warning ! this text assumes my personal conditions, other locations might
use other net voltages like 380V or 110V instead of 220V)

OUTPUT
======

This is the schematic of an output device. When the SIG wire is connected
to ground (or a logic 0 from yout parallel port), it will switch the
relais to inactivated state.
When the SIG wire is connected to a 5Volt potential (or a logic 1 from your
parallel port or any ttl device), it will switch the relais to activated
state.
It needs a 12V Vcc to operate the relais. I build the resistor R1 and
transistor T1 seperatelly from R1, D1, D2, REL1. I then put the ttl to
12V convertor in the MER (Main Equipment Room). From there a wire goes to
the actual switching location (inside a lamp, tv, wall socket, whatever)
and is connected with the relais control (R2, D1, D2, REL1).
If you have a couple of units spread over the premises, concentrate all
bundles and split off where necessary (thus creating a sort of
'backbone'). This means you can use a general feed of +12V and gnc shared
by all units (thus using only 1 wire) instead of multiple feeds for
individual units.
				
				+12V
				  |
		  ________________|
		  |		  |_________________
		  |		__|__		   |
		 _|_		 / \   D1=1N4007   |_
		|   |		/___\		     \
		|   | R2 = 1K	  |		     /  REL1=12V, use a 
		|___|		  |		     \   model for 220V 
		  |		  |		   __/   and as much amperes
		__|__		  |		   |     as neccesary (1A,5A)
		\ | / D2=LED	  |		   |
		_\|/_		  |________________|
		  |		  |
		  |_______________|
		  	|
			|
			| C
		  |    /
		  |  /
         ____	B |/
  IN ---|____|----|   T1=bc547
    	 R1=	  |\
	  10K	  | _\|
		  |    \
			| E
			|
			|
		      __|__
		       ___
		        _



Input
=====

There are several types of input. One of them is infra red (for remote
controls). I used the excellent schematics which are on one of the several
lirc homepages. The gpc homepage (chaos.concepts.nl/~gmc or
www.bitcon.nl/~gmc) has links to four different lirc sites. The lirc
solution includes an excellent linux driver for the module (just 5 parts,
really easy to build) and software for (mostly american) remote controls.
I had to redo the software for european rc's, and that code is included in
the gpc distribution.

Another form of input is a simple on/off switch. Maybe one of your
lightswitches. Normally the switches on the walls you use to turn on/off
your light are wired with 220V. Once you have installed an output module
(see first schematic) on the light, you can disconnect the switch from the
220V circuit since it isn't needed anymore. You could use virtually any
switch you can get your hands on btw.
Now hook up 12 or 5 volts to the one end of the switch, and another wire
to the SWITCH wires of one of the below schematic (respectively for 5V or
12V). This device will filter out any interference, and will output a nice
TTL signal to your parallel port.

For 12V:

			       +5V
				|
				|
				|
			        | C
			  |    /
			  |  /
                ____	B |/
SWITCH----|----|____|-----|      T1=bc547
          |   R2=4k7      |\
         _|_		  |  \|
   R1=  |   |		  |  - \
    10K	|   |		  |     | E
	|___|			|
          |			|______________ TTL (to parallel port)
	  |			|
	__|__		       _|_
	 ___		      |   |
	  _		      |   | R3=1K
			      |___|
				|
				|
			      __|__
			       ___
				_


For 5V:



SWITCH----------------------TTL (to parallel port)
		|
	       _|_
	      |   |
	      |   | R1=1K  (ain't electronics like magic?)
	      |___|
		|
		|
	      __|__
	       ___
		_

Well have phun experimenting but remember ! Never hold the high voltage
lines while they are operative (I did a couple of times and it gave me an
unpleasant buzz :)

signed, gmc