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"Toggle" circuit?

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JackSmith

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Hi all,

I need some help...I'd like to build a circuit that will simply toggle between two outputs when power is applied to an input. That is, the first time power is applied, light A should turn on, then turn off when power is removed from the input. The second time power is applied, light B should turn on, then turn off when power is removed. The third time power is applied, light A comes on again, and so on.

Is there any digital or analog circuit that will do this? Simplicity is key, but I'll try just about anything once.

Thanks,

Jack
 
Since you need to remember state with power off, you must use a mechanical toggle (pulse escapement), or some sort of non-volatile memory.

How about a compromise where you use a CMOS low-power latch with a battery keep-alive?
 
An alternating action relay may do what you want: https://www.amazon.com/712XBXCK-120V-Electromechanical-120VDC-120VAC-Alternating/dp/B00WDH5BJS (search term:alternating relay)

One application is to equalize usage of dual-pump systems. When power is first applied, say from a float switch, pump A works. After the float opens and power is re-applied, pump B works. There are lots of vendors on the web, That is just one example. This link lists several brands: https://www.directindustry.com/industrial-manufacturer/alternating-relay-83432.html

John
 
Since you need to remember state with power off, you must use a mechanical toggle (pulse escapement), or some sort of non-volatile memory.

How about a compromise where you use a CMOS low-power latch with a battery keep-alive?

I'm intrigued - can you give me an example circuit? Not sure what I'd search for, exactly.

Jack
 
An alternating action relay may do what you want: https://www.amazon.com/712XBXCK-120V-Electromechanical-120VDC-120VAC-Alternating/dp/B00WDH5BJS (search term:alternating relay)

One application is to equalize usage of dual-pump systems. When power is first applied, say from a float switch, pump A works. After the float opens and power is re-applied, pump B works. There are lots of vendors on the web, That is just one example. This link lists several brands: https://www.directindustry.com/industrial-manufacturer/alternating-relay-83432.html

John

Those are pretty cool, but I guess I should have said that I'm running this all from a 12v DC battery setup.

Thanks,

Jack
 
... I guess I should have said that I'm running this all from a 12v DC battery setup...

How much current can the circuit draw from the battery with the switch open?

What type of switch?
SPST? (Form A)
SPDT? (Form C)
 
How much current can the circuit draw from the battery with the switch open?

What type of switch?
SPST? (Form A)
SPDT? (Form C)

I currently have everything at less than 1 amp, actually around 300 mA. However, it can draw more if needed - that's just what I have so far.

As for the switch, it would be a SPST. Just switching between circuits A and B. At least an SPST should be all I need.
 
I currently have everything at less than 1 amp, actually around 300 mA. ...
That is the load current when the switch is closed. I was asking about the allowed current drain with the switch open; nothing to do with your load.

This is the current required to maintain the state memory. Using a CMOS latch, for example, the standby current might be ~10uA. Since that drain would be 24/7 (forever), would that bother your battery?
 
Before you design, build anything, define load voltage current, inductance, capacitance or specify exact loads by Model.

Motors take 8x rating on switch contacts than lights.
 
That is the load current when the switch is closed. I was asking about the allowed current drain with the switch open; nothing to do with your load.

This is the current required to maintain the state memory. Using a CMOS latch, for example, the standby current might be ~10uA. Since that drain would be 24/7 (forever), would that bother your battery?

Ah, sorry! I didn't sleep much the last few days and thought I'd read your post, but missed that bit. But to answer your question, yes, 10uA would be completely acceptable.
 
Before you design, build anything, define load voltage current, inductance, capacitance or specify exact loads by Model.

Motors take 8x rating on switch contacts than lights.

Thanks, Tony. Yep, I figured as much when I designed it, and was pleasantly surprised that actual working current is well within the range I expected, even on the low side.
 
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