12v Latching Relay Question

Thread Starter

dmuth23

Joined Apr 18, 2017
2
I'm not sure if this is the right place for this question, but I'm looking for a relay that feeds a 12v load with it's own power supply that is normally on or closed, but latches open or off when a momentary button is depressed. I.E When power is initially fed to it, it feeds power, but when a momentary button is pressed, it removes power and latches that way until power is cycled. Any thoughts or ideas?
 

Alec_t

Joined Sep 17, 2013
15,118
Welcome to AAC!
How much current does the load draw? I ask because a solid state switch might be an optional replacement for a current-hungry relay.
 

MaxHeadRoom

Joined Jul 18, 2013
30,658
I have a circuit for a relay flip flop with single button, if that is what you are looking for.
Apart from the relays, just a couple of diodes and caps.
Max.
 
There are probably literally hundreds of ways to do something like that but you will need to clarify a few things to get an answer you can use...

You say the load has its own power supply, which is fine and suggests you would use one of the relays contacts to switch it independently of your control circuit.
However you also talk about cycling the power to reset the system once the load is off... Do you mean the power to the load, the relay control circuit or both?

Can you clarify stating what needs to happen in what order...
Something like:-
Load supply always on.
Control supply on - Load switched on.
Control supply on / button press - Load switched off.
Control supply on / button press - Load remains off
Control supply off - load remains off

I don't know if that is what you want but if it is then two relays is there simplest option.
If you can be a little more specific with your requirement I, and many others will be able to give you a specific answer with a circuit.

Al
 

Thread Starter

dmuth23

Joined Apr 18, 2017
2
There are probably literally hundreds of ways to do something like that but you will need to clarify a few things to get an answer you can use...

You say the load has its own power supply, which is fine and suggests you would use one of the relays contacts to switch it independently of your control circuit.
However you also talk about cycling the power to reset the system once the load is off... Do you mean the power to the load, the relay control circuit or both?

Can you clarify stating what needs to happen in what order...
Something like:-
Load supply always on.
Control supply on - Load switched on.
Control supply on / button press - Load switched off.
Control supply on / button press - Load remains off
Control supply off - load remains off

I don't know if that is what you want but if it is then two relays is there simplest option.
If you can be a little more specific with your requirement I, and many others will be able to give you a specific answer with a circuit.

Al
Thanks Al, I'll clarify a little bit.
Start:
Control Power Off - Load Power Off
Control Power On - Load Power On

Then:
Button Press - Toggle Load Power

Regardless of Current State of Load Power, Control Power Off - Load Power Off
There will never be a time that there is no control power, that the button has functionality. I'm a newb, so let me know if that'll help sort out what I'm looking for.

Thanks!!
 

Kermit2

Joined Feb 5, 2010
4,162
You need a simple self latching relay config.

You put load on one set of contacts that keep load powered while relay if OFF.

You put ground directly on one end of coil and use momentary switch that applies control voltage to coil ONLY when the button is pressed. This breaks the set of contacts sending power to the load.

On the second set of contacts you connected the switched pin to same point on the coil the momentary switch is hooked to. Connect control voltage to contact that is closed when relay is activated. This latches the relay by applying voltage to the coil when it is first turned on.

You can reset by putting a momentary off switch in series on the latch wire or on the ground end of the coil, or you can briefly remove control power some other way to reset the relay.
 
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