Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!ncrlnk!ncrcce!ncrons!johnson
From: johnson@ncrons.StPaul.NCR.COM (Wayne D. Johnson)
Newsgroups: sci.electronics
Subject: Re: Using computer to switch high current circuit
Message-ID: <225@ncrons.StPaul.NCR.COM>
Date: 5 Jan 90 21:02:48 GMT
References: <1990Jan2.005157.12780@uokmax.ecn.uoknor.edu>
Reply-To: johnson@ncrons.StPaul.NCR.COM (Wayne D. Johnson)
Distribution: na
Organization: NCR Comten, St Paul
Lines: 23

In article <1990Jan2.005157.12780@uokmax.ecn.uoknor.edu> blpike@uokmax.UUCP (Brian Lee Pike) writes:
>I am trying to build a circuit that allows my Commodore 64 to connect a
>110,000 microfarad (that's not a typo, I mean 0.11 farad), 18 volt capacitor

There is a device known as a solid state relay.  It consists of a LED optically
coupled to a triac or transistor.  When the LED lights, it triggers the 
triac.  I have used these on circuits as heafty as 400 Amps (with a 4' x 1'
heat sink of course).

I'm not sure how these would work with DC, with a triac, you have to bring
the voltage across the power terminals to almost 0 to turn them off.  There
may be a version that will turn on and off with the light (as the name implies).

The Opto triacs I've seen are too fast, they tend to generate RF noise on
the line because the signal is so square.

I've seen Solid State Relays at our local Electronics Surplus for $3 to $10.

-- 
Wayne Johnson         |  Is a baby's life worth more than the right to 
NCR Comten, Inc.      |  make a choice?  Babies are people too.
Roseville MN 55113    +-----------------------------------------------------
(Voice) 612-638-7665   (E-MAIL) W.Johnson@StPaul.NCR.COM