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Post 24 made on Wednesday October 28, 2020 at 16:22
Ernie Gilman
Yes, That Ernie!
December 2001
I just realized that, while you talk of 8 relays, you have not told us how many combinations of these relays are needed. It could easily be a dozen, or as few as three, combinations. That will decide how complicated the control circuitry needs to be.

Let me offer an outrageously retro idea of how to handle this. The only thing that makes it not retro is that it will probably work great in an RF environment, especially if you use RF filtering on all power leads. You mentioned chokes, I believe; don't forget bypass capacitors.

Diode logic. That is, if in one case you need relays A, b, and iii turned on, take three diodes and run each one to a relay, one being A, one being b, and one being iii. Supplying voltage to that combo of three diodes turns on those three relays. Assemble separate diode combinations for the other combinations you need. Wire 'em all up. I once built a controller for a digitally addressed 8-position loudspeaker demonstration switch (MTI in Oregon, if it matters). The "controller" was several diodes, several switches, and an IC that latched eight outputs to whatever state they were in when a trigger voltage went to zero.

This involves custom work from the start, but you're then TOTALLY in control of all aspects of shielding.

On October 25, 2020 at 17:54, ftbrady said...
What is the name of the xmtr fob and receiver product? If clicking the fob can causes a switch to change state on the receiver, then I suppose all I have to deal with is

I've seen at least two brands, and they're not always in stock. For a long time I only saw these during Christmas season (that is, most any time after March 1...). Over the last several years these have been available year round at my local Home Depot. And I harvested the picture from the internet. Several models can be found there.

* replacing the xmtr button with two activation wires
* finding 8 different IR IDs

These are RF controlled, not IR controlled. Of course, your RF field might be a problem.
* wire the rcvr switch to a 12vdc supply to send to a relay.

Each receiver switch has a 120V power socket, so a wall wart on each would give you the switchable power.

NOTE: you can only switch one of these things at a time, which might introduce loading problems to your transmitter. On the other hand, if there are any places where two relays ALWAYS have to be switched at the same time, that's easy -- hook a wall wart's output to two relays.

I don't suppose there are any 8 channel versions of the product? Or products that expose their xmtr wiring rather than embedding it in a fob?

There are three channel versions, but I have no idea whether there's just one such product (i.e. with channels 1, 2, 3 only) or several (i.e. with other channel combinations).

Really, though, I offered those halfway as a joke, since they appear to be total misfits for any serious electronics that we are likely to do, yet their specs matched the overly general description of what was needed.

EDIT: I just caught up with where this thread has gone. It's an example of the breadth of knowledge and helpfulness this great group of people have to offer.

Last edited by Ernie Gilman on October 28, 2020 17:13.
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