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Resistor-Diode-Relay Logic Source Selector
Resistor-Diode-Relay Logic Source Selector
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Old 16th March 2013, 05:48 PM   #1
pmbrunelle is offline pmbrunelle  Canada
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Default Resistor-Diode-Relay Logic Source Selector

Here is my rough concept for the logic of a source selector. I wanted no microcontroller, and the concept should be easily expandable to a number of inputs.

Desired functionality:
When you push a button, any other active source is deselected, and the new source is connected, even when you release the button.

Buttons are DPDT momentary toggles or pushbuttons.

Relay coils need to be 12 VDC. 5 VDC relay coils have guaranteed turn-off voltages close to the 0.7 V diode drop.

The relay that selects the input might be the same one as for the logic, or it could be separate...

Does this idea make sense?
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Old 17th March 2013, 12:44 PM   #2
Mooly is offline Mooly  United Kingdom
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Resistor-Diode-Relay Logic Source Selector
I don't get it tbh ... you need to draw it much much clearer and with one relay in the conducting state. It seems a very "clumsy" way of doing things tbh, sorry that's not meant as a criticism.

This is a simple selector (I'm sure it came from someone on the forum, maybe Lineup from a few years back) and uses one CMOS chip. No micros, no clocks.
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Old 17th March 2013, 02:32 PM   #3
mickeymoose is offline mickeymoose  Canada
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Here is an interlocking 4 pos. switch schematic, easy to expand. E
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Last edited by mickeymoose; 17th March 2013 at 02:34 PM.
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Old 20th March 2013, 03:10 AM   #4
nezbleu is offline nezbleu  Canada
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Resistor-Diode-Relay Logic Source Selector
Here's another one using a single 40174 hex D-type flip-flop, I used it on my preamp.


The momentary switch is the clock for the flip-flop.
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