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From: kenny@m.cs.uiuc.edu
Newsgroups: sci.electronics
Subject: Re: Switching from 5V to 120V
Message-ID: <21000063@m.cs.uiuc.edu>
Date: 23 Feb 90 17:43:37 GMT
References: <3709@uceng.UC.EDU>
Lines: 17
Nf-ID: #R:uceng.UC.EDU:3709:m.cs.uiuc.edu:21000063:000:758
Nf-From: m.cs.uiuc.edu!kenny    Feb 22 20:43:00 1990


Henry Spencer writes:
>Relays are possible, but the best way (my opinion) is to use a 3011 or
>one of its relatives -- an optoisolator with a small triac as its output --
>to drive a larger triac.

An alternative to this is something along the lines of a Potter &
Brumfield OA16-66, which has a one-amp triac on board -- more than
enough for the 25-watt load that the original poster envisioned.  It's
in a 16-pin DIP, and needs a heat sink, but the package is insulated.

5-volt relays still have the optoisolator approach beat if parts cost
is the major issue, but are slow to switch, noisy (both acoustically
and electrically), tend to fry driver transistors, and tend to fail at
the crucial moment.  I agree with Henry about optoisolators.

Kevin	KE9TV