From: Sean Breheny <shb7@cornell.edu>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Wed, 18 Aug 2021 13:07:01 -0700
Subject: Re: [EE] off the shelf TRIAC module?
Thread-Topic: [EE] off the shelf TRIAC module?
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Dwayne,

You said "Note that you must choose
a SSR that allows phase control (as opposed to one that has internal
zero-cross detection)." Are you talking about the type of turn-ON criterion
(random fire vs zero-voltage switching)? Because all triacs turn OFF on
zero-crossing (of the current).

It also sounded to me like the original poster was looking for, not a
thermostat, but a module which accepted an analog input which indicated the
% duty and which automatically converted this to a "time to fire" the triac
internally.  If that is indeed what he wants it is important to note that
phase control isn't quite like PWM. It is inherently nonlinear in its %
duty to effective output voltage (or average power) because the majority of
the power for a resistive load is near the peak of the sinusoid.

Sean


On Wed, Aug 18, 2021 at 3:56 PM Dwayne Reid <dwayner@planet.eon.net> wrote:

> Hi there, Jason.
>
> We use a variety of 1/16 DIN PID temperature controllers.  Although
> the units we use have a 4-20mA output, they are also available with
> both relay (on-off) control as well as phase control output suitable
> for driving a standard Solid State Relay.  Note that you must choose
> a SSR that allows phase control (as opposed to one that has internal
> zero-cross detection).
>
> dwayne
>
>
> At 05:37 AM 8/18/2021, Jason White wrote:
> >Yeah, you are right. I suppose most applications would just implement
> >control signal synchronization with respect to mains in a microprocessor=
..
> >
> >For some reason, I was picturing a self contained module that took an
> >analog control signal in - a glorified light dimmer intended to be wired
> up
> >for industrial use cases (eg. fast cycle by cycle control of power
> >commanded by a 0-10V output from a PID module or similar)
> >
> >Jason White
>
>
> --
> Dwayne Reid   <dwayner@planet.eon.net>
> Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
> 780-489-3199 voice   780-487-6397 fax   888-489-3199 Toll Free
> www.trinity-electronics.com
> Custom Electronics Design and Manufacturing
> --
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