Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!deimos.cis.ksu.edu!uxc!garcon!tuna.cso.uiuc.edu!kline
From: kline@tuna.cso.uiuc.edu (Charley Kline)
Newsgroups: sci.electronics
Subject: TTL to 1500 watts - query
Message-ID: <1164@garcon.cso.uiuc.edu>
Date: 6 Jun 89 02:30:19 GMT
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Organization: University of Illinois at Urbana-Champaign
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Having recently been promoted to assistant Technical Director at
the local community theater, and being the only person there with
a degree in an engineering discipline, naturally the "neat gizmo"
wishlist fell to me. Top on the TD's list is a box which will
perform some complicated sequencing of lighting.

Now, I've had as much logic design as the next guy, so the
sequencing part is easy (shift registers and such). Where my
knowledge of how electrons in silicon behave is sorely lacking is
in the part that's going to have to take the delicate little TTL
signal from my shift register and use it to turn on and off a
1500-watt lighting instrument.  A mechanical relay is right out
because our tech booth is right next to the audience and has no
sound insulation to speak of. So this thing is going to have to
operate silently.

I recall from the elemental projects I built in high school that
there's this thing called a triac which is essentially two SCR's
in parallel and facing opposite directions. I figure this is what
I want to use (but please correct me if I'm wrong). The problem
is that I have no idea how to connect this thing. What, just put
the load in series with the main terminals of the triac and con-
nect the gate to the TTL signal? Surely not. And I looked in the
Newark catalog under "Triacs" and they had a million of them, all
rated by "RMS", "Itsm", four different kinds of "Igt" and "Vgt",
and "Vgrm".

Can someone help me with these numbers and tell me how to connect
one?  Thanks in advance!


In a related vein, I remember seeing some talk here from people
who were doing technical theater projects. Who are you all? I'm
on a rampage to evolve our VERY low-tech theater into the 1990's,
and I could use some good ideas as well as some technical gui-
dance, because as I say, I'm not much good at high-energy elec-
tronics. And besides, us technical theater nerds should hang out
together anyway. :)

-----
Charley Kline, University of Illinois Computing Services
kline@tuna.cso.uiuc.edu
{uunet,seismo,pur-ee,convex}!uiucdcs!uiucuxc!kline

"They always said I would be nothing but a fish head. And look at me now."