gEDA-user: SSRs vs. discrete triacs

Randall Nortman geda-lists at wonderclown.org
Sat Mar 3 10:34:35 EST 2007


I need to switch <1A @ 24VAC loads, and I've been looking at various
DIP-package SSRs.  The cheapest ones are MOSFET-based with no
zero-cross circuit.  Triac-based SSRs with zero-cross circuits are
more expensive.  But comparing this to building my own out of an
opto-triac (for isolation) and a discrete power triac, I can build it
for less even than the cheap MOSFET SSRs, while taking up only
slightly more board space.  Plus, I can get a zero-cross opto-triac
and still be cheaper.  Am I missing something?  Doesn't integration
pretty much always result in cost savings?  I guess in this case it's
a matter of power dissipation limiting the ability to integrate it all
into a single package?  Is there any reason to prefer the integrated
MOSFET SSRs?

TIA,

Randall


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