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From: murray@sun13.scri.fsu.edu (John Murray)
Newsgroups: sci.electronics
Subject: What are some typical characteristics of mechanical relays?
Message-ID: <2640@sun13.scri.fsu.edu>
Date: 31 Mar 91 20:48:49 GMT
Organization: SCRI, Florida State University
Lines: 29

Howdy, folks. I'm in the process of doing some cheap-and-cheezy design
work as the preliminary stage of a hobbyist project, and I'd like to
get some typical characteristics of mechanical relays.

Application: High-current (peaks may be around 40V, 20A or more) switching
of the magnetics on a coil gun... :-)

Why relays, and not SCR's or something? I've got some relays sitting around
unused, (take-outs from surplussed equipment) and swallowing the cost of a
couple of pounds of magnet wire is going to be tough enough by itself. Besides,
it's more challenging this way! And think of the great noises! (open-frame
style relays..)

So, specifically, I'd appreciate any information on typical switching times
of relays. I assume times would be in the milliseconds range, is this
about right? Also, which is typically faster, turning on (energizing the
coil) or turning off?

I know this info is entirely dependent on the specific relay, I'm just
looking for ballpark figures (so far..)

(Anybody have any handy hints about driving relay coils with
phototransistor/led pairs as detectors?)

-- 
*Standard Disclaimers Apply*|        ---Get Out Of HELL Free!---
John R. Murray              |The bearer of this card is entitled to forgive
murray@vsjrm.scri.fsu.edu   |Himself of all Sins, Errors and Transgressions.
Supercomputer Research Inst.|                                -- D. Owen Rowley