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3 switches, 7 lamps (no solid state)

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Cyberdragon:
I made a circuit using 7 relays, but that's with the lamps and coils in the same circuits (so either low or mains).


--- Quote from: Benta on February 27, 2019, 08:34:10 pm ---Nice little exercise  :)

You'll need 7 spst relays for the lamps, 3 spdt switches and 4 spdt relays for the additional logic.


--- End quote ---

only 4 spdt? I tried using only 4 spdt and couldn't figure it out. note DPDT relays allowed)

Nusa:

--- Quote from: Benta on February 27, 2019, 09:15:29 pm ---
--- Quote from: larrybl on February 27, 2019, 08:48:09 pm ---000  0ff
001  lamp 1
010  lamp 2
011  lamp 3
100  lamp 4
101  lamp 5
110  lamp 6
111  lamp 7

Binary says it may ne possible with three switches and 7 relays, How to wire it up  :-//

--- End quote ---

That is very basic and obvious. But the problems is that both switches and relays are SPDT. With DPDT switches, only the 7 relays would be necessary.
To emulate the DPDT switches, 4 extra relays are needed.

--- End quote ---
Strange, With 7 spdt relays, I can't see any need for more than 3 spst switches. With dpdt switches, you can make do with 4 spdt relays I believe.

It's easier to think of this as an 8 light problem, then simply eliminate one light when you're done.

ebastler:
Assuming that DPDT relays are allowed, but only SPDT switches:
Three switches and three relays should be enough.

* Switch 1 directly multiplexes the voltage to two channels.
* Switch 2 controls relay 1 to multiplex those 2 to 4 channels.
* switch 3 controls relays 2 and 3 to multiplex those 4 to 8 channels.Use six SPDT relays instead if you want to avoid DPDT.

Benta:
"DPDT relays allowed"
This is not what you originally wrote.  :--

In that case, 7 SPST for the lamps, and 2 DPDT relays for logic.

Edit: 7 SPST, not SPDT.

Nusa:

--- Quote from: ebastler on February 27, 2019, 09:47:21 pm ---Assuming that DPDT relays are allowed, but only SPDT switches:
Three switches and three relays should be enough.

* Switch 1 directly multiplexes the voltage to two channels.
* Switch 2 controls relay 1 to multiplex those 2 to 4 channels.
* switch 3 controls relays 2 and 3 to multiplex those 4 to 8 channels.Use six SPDT relays instead if you want to avoid DPDT.

--- End quote ---
Now take the next step and use switch 2 directly instead of using a relay. And if you decide to allow switch 3 to be 4pdt, you can eliminate all relays.

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