Looking for a 12 volt simple relay circuit that can stay on even when power is removed. When a momentary contact activates the circuit, I want the relay to stay in its on position even when power is removed. The only time that the relay will be deactivated is when the momentary contact is activated again. Any help greatly appreciated. Thanks

 

have you heard of latching relays?

 

That sounds exactly like an alternate action relay! I have two og them, both removed from older television remote control assemblies. Actually, it is the contact that stays activated, the relay mechanical part moves with the coil being powered, the alternate action is the switch closing and opening.

 

have you heard of latching relays?

I'm not very good at circuit design. Can you help me? Thanks

 

A latching relay has a single coil and is DC powered. The two leads will either activate or deactivate the relay. A momentary (for instance) Positive charge will pull the normally open contacts closed. There's also a magnet involved. The magnet will hold the relay in the closed position even with no power to the relay. When a momentary (for instance) Negative charge is sent it will repel the magnet and the normally open contacts will once again fall into the open position.

I'm not on my big computer so I am not near my drawings. Hopefully this description will help you understand.

 

this might help:

https://au.rs-online.com/web/content/discovery/ideas-and-advice/latching-relays-guide

 

Many "alternate action" relays do not require ANY special circuit to function. They are not the same as an latching relay using opposite polarities, as describer earlier. BUT an alternate action relay will provide the requested results.

 

Looking for a 12 volt simple relay circuit that can stay on even when power is removed. When a momentary contact activates the circuit, I want the relay to stay in its on position even when power is removed. The only time that the relay will be deactivated is when the momentary contact is activated again. Any help greatly appreciated. Thanks

One suggestion using a 2 coil 12V latching relay.
Operation:
Press and hold Sw1 until The relay activates then immediately release the switch. Hold time is appx 1.5 to 2 seconds.
The relay is now latched ON and power can be removed.
When power is back ON press and hold Sw1 again until the relay deactivates and immediately release the switch.

 

Is a latching relay also a flip flop?

 

There is not any scheme that is simpler than an alternate action relay, which relay types are certainly available. Of course, it would need to be purchased from a larger electrical distributor because I doubt that it would be an amazon or youtube offering. And who knows what ebay might present.

 

Is a latching relay also a flip flop?

Basically.
But a latching relay requires no steady-state power to stay it its selected state, whereas an electronic flip flop does.

 

One suggestion using a 2 coil 12V latching relay.
Operation:
Press and hold Sw1 until The relay activates then immediately release the switch. Hold time is appx 1.5 to 2 seconds.
The relay is now latched ON and power can be removed.
When power is back ON press and hold Sw1 again until the relay deactivates and immediately release the switch.
View attachment 341738

Thanks. Just what I was looking for. What website do you use for getting these parts.

 

Thanks. Just what I was looking for. What website do you use for getting these parts.

Is there anything on amazon I could order

 

Thanks. Just what I was looking for. What website do you use for getting these parts.

First need to know what the relay contacts will be used for as far as voltage and current required.
In other words what is the load?

 

First need to know what the relay contacts will be used for as far as voltage and current required.
In other words what is the load?

I'm trying to bypass the foglight switch on my car. It's a momentary contact on the column. When I activate it, the fog lights come on, but when I turn the car off the relay resets to the off state. I'm trying to activate the switch once and have it keep the on state even when I turn the car off.

 

Not sure if the circuit I posted will work correctly in your application.
To turn ON and OFF the fog lights requires a momentary push of the switch on the column correct?

 

Not sure if the circuit I posted will work correctly in your application.
To turn ON and OFF the fog lights requires a momentary push of the switch on the column correct?

Yes. That is correct. As a matter of fact, I installed a device that disabled the auto start/stop on my car and it does the same action as the circuit I'm looking for. The start/stop is a momentary push button. The device remembers the last state the setting was and keeps it even when the power is removed. That's what I'm trying to do with my fog lights

 

Yes. That is correct. As a matter of fact, I installed a device that disabled the auto start/stop on my car and it does the same action as the circuit I'm looking for. The start/stop is a momentary push button. The device remembers the last state the setting was and keeps it even when the power is removed. That's what I'm trying to do with my fog lights

I have the ability the provided constant 12 volts if that helps

 

The device remembers the last state the setting was and keeps it even when the power is removed. That's what I'm trying to do with my fog lights

Problem or may not I'm seeing with my circuit is that the relay contact remains closed and not momentary.
It will hold this setting until reset.
Will that be a problem wired across the the Fog switch in the column?
Or do want to use a separate relay contact to activate the Fog lights not connected with the column switch?

 

I'm trying to bypass the foglight switch on my car. It's a momentary contact on the column. When I activate it, the fog lights come on, but when I turn the car off the relay resets to the off state. I'm trying to activate the switch once and have it keep the on state even when I turn the car off.

Don't bother! The car computer will switch it off even if you use a maintained contact switch. I leave the parking lights on in my car and five minutes later the computer assumes that i forgot them on and switches them off. When I park alongside a dark road I want those lights to stay on until the battery runs flat dead! Much better than getting hit by a car who does not see the car. But evidently somebody does not understand the purpose of parking lights.