Relay that turns device off when ignition is turned off

I am drawing a total blank in my memory here. I know I have made up these circuits before, but I can't find the diagram or parts list that I used. Here's what I want to do:

• Build a circuit that is powered by 12 volts from the battery, but activated by an ignition-on circuit.
• The switch that turns on the device is a momentary contact push button.
• Pushing the button turns on the device.
• Pushing the button again turns off the device. Or pushing a second button. Or using a SPDT momentary contact rocker.
  
• Turning off the ignition turns off the device, and it won't turn the device back on until the truck is restarted and the button is pushed.

I recall that this uses a fuse or two and at least one relay, but to save my life I can't recall what the relays are. Or is. The current load on the device, at 12 volts, will run maybe 5A.

Sound familiar to anyone? @caribe makaira The memory is the second thing to go. Any help, even snarky, that'll jog my memory, will help. I don't want to go physically tearing into prior work to get that "aha!" moment.

Similar devices are used on stationary power tools, but they are larger and use higher voltages.

 

Using a fused ignition source will get you the ON only at Engine/ACC on. And also turn off when ALL is OFF. If you want control after the added IGN activated circuit is on, then add a switch to the relay coil ground. That would allow control before or after the circuits is activated.
What are you assembling?

 

I'm planning a pusher fan for a radiator. Not exactly like the circuit envisioned in the Toyota TSB.

Controlling the circuit from an "ignition on" circuit will ensure that it turns off with the engine. But I don't want the fan to turn back on by itself when the driver turns the engine back on.

So controlling it from an "ignition on" circuit will accomplish about 80% of what I need.

 

The added switch on the relay coil ground would control the OFF, when needed.

 

Momentary switch (for the relay ground) and latching relay possibly? Momentary switch momentarily activates the latching relay which then holds until ignition is cut?

 

You'd need both, (momentary switch and latching relay).$$$

 

Right, that’s what I’m suggesting. The “possibly” was for both of them, though I could see how it doesn’t read that way.

 

Johnny has a gadget, tells Johnny.

 

Get's expensive for something that could be a simplicity.

 

Yep…more fun wiring to run too.

 

you're looking for a latching relay circuit.

can also look up start/stop relay diagrams.





or, the ultra lazy can spend $6 on Amazon(i used to build my own, but i can't even buy the parts for that price!)

$9 Flip Flop Relay Module - Mini 6-24V Bistable Self-Locking Switch

https://www.amazon.com/gp/product/B07VL9DBGT

 

The relay at Amazon is inexpensive enough to buy two and experiment. Thanks.

 

just be warned, many pusher fans can pull upwards of 20-40A at full power, so it might not be enough.

 

Yup. I am looking at a dual relay setup, anyway.
Small relay to activate the big relay.