🚀 go-pugleaf

In article <693@thunder.LakeheadU.Ca> dnwangus@flash.LakeheadU.Ca (Dave Angus) writes:

>I'm not much good at drawing schematics in ASCII, but here's the
>schematic (more or less) from the Computer Shopper article.
>The article was written by George Toft.  Any errors or mistakes
>are mine.

Because the circuit uses relays and connects to the computer, there 
is a danger that the high voltage spikes generated by relay coil
can cause harm to the computer circuits. When the current in the
relay coul is switched off, a high voltage spike is generated in 
the coil. It would be a good idea to add a reverse-biased diode
in parallel with the relay coil to avoid those spikes. The diode 
can be any common type, for example 1N4148 or something like that.
Some special relays have internal diodes for that purpose.

Here is the schematic from Dave Angus's original article slightly
modified. I have added the diode to the picture.

pin 1  (+5 volts) ---------------------------------------
		     |        |                         |
		     |        |                         |
		     |        \                        ---  Right switch
		     |        /                        ---  [Down]
    Left switch     ---       \                 --------|
    [Up]            ---       /        Diode   _|_      |
                     |        |                / \      |
		     |        |--------        ---    (   ) Relay Coil
		     |        |       |         |       |   for left/right
		     |        \       |         --------|   [up/down]
		     |        /      ---                |
		     |        \       /    N/C relay    | 
		     |        /      ---   contact      |
		     |        |       |                 |
		     |        |       |                 |
pin 6  (Input 0) ----------------------                 |
[pin 3 (Input 1)]                                       |
							|
							|
pin 4 (ground)  ----------------------------------------


















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