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Date:	Tue, 18 Jun 2002 10:06:29 PST7
From:	Ray Davison <raydav@charter.net >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: Printer switch boxes

Content Type: text/plain

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> intermittently cause an "interruption" in the connection (this used to
> drive young TTL designers nuts when they tried to trigger their test
> circuits mechanically).

I guess that depends where you went to school. That is not something we
were left to find out the hard way.

> Yes. I'm glad *somebody* around here uses an oscilloscope!

I have four scopes, plus an ignition scope, but I didn't need one to
determine my 550C would not work with my mechanical switch box. In this
case "they" were right.
>
> Good advice, thanks Rocky. (The debouncing is typically done with a
> "one-shot" circuit on each data line which makes the switch look like it
> is electronically closed even while it's still bouncing.)

I have a clock radio I fixed by just hanging a ten mic cap across the
push button.

> If you are going to throw the switch while it's carrying data then you
> ought to at least solder some zeners onto the data lines.

I assume you mean a pair of them back-to-back.

> Some of the mechanical switch boxes might already have them.

Not likely.
>
> (zeners are cheap).

So are electronic switches.

Peter: What printers do you have that work with mechanical switch
boxes? I have several switches and printers, and if I have nothing
better to do I may play.

However, even if it worked, what's the point. Why would I want have to
mount a switch, with all the cables, where I can reach it, rather than
behind everything and switch it from the keyboard?

Ray

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