Thread: momentary switch -> latching circuit?

havent listed the end use because atm i havent decided exactly what i want to run from the circuit, but for the purpose of this, imagine i want to trigger a regular automotive relay..... from that i can turn on/off whatever i need to

what i am certain of, is that i have no other use for a momentary switch, but the bezel and switches are available to take up what would otherwise be a blanking panel

Originally Posted by Sprint

havent listed the end use because atm i havent decided exactly what i want to run from the circuit, but for the purpose of this, imagine i want to trigger a regular automotive relay..... from that i can turn on/off whatever i need to

what i am certain of, is that i have no other use for a momentary switch, but the bezel and switches are available to take up what would otherwise be a blanking panel

Then the easiest solution is to grab one of the VW relays I described earlier, and wire the switch directly to that. Next easiest solution, grab one of the Jaycar latching relays, and use that to drive the coil of a standard automotive relay.

considering where i am, it's gonna be easier to hit the local jaycar shop than find a wrecker with VW's.....

Dammit, I did a bit more digging on the Jaycar relay and fond that it's not a true latching relay. The pdf they provide doesn't give a pinout of the relay, however the following link does:

http://info.tactnet.co.jp/shinmei/e/.../pdf/E_RSB.pdf

Pin 1 is coil 1 positive (12v)
Pin 16 is coil 1 negative
Pin 2 is coil 2 positive (12v)
Pin 15 is coil 2 negative

Why two coils? If you apply momentary 12V to coil 1, the contacts will "set" (toggle) to the other position and stay there, even if you disconnect the 12V.
If you then apply a momentary 12V to coil 2, the contacts will "reset" (toggle back) to the original position.

In other words, you can't operate this relay with a single momentary switch, which you want to do So it's back to the VW relay until I find something else.

[edit]You can do it with for standard relays seriesed up..... else we're getting into the realm of more complex circuitry....[/edit]

Alright, how good is your understanding of electronics, because there are a couple of ways of doing this. If you know anything about IC's, then the simplest is to use a 7404 hex inverter from Jaycar to toggle a standard relay on and off with a pushbutton circuit.

Like the rest of us, I am not sure what you want to do, But from just turning on relay, why not just buy (i will assume you have either a D1 or D2 as you do say factory switches that are momentry) (this is all James Bondish isnt it) the latching switches from a wrecker/dealer. They are all the same size (you may have to shave the alignment tags as they are tagged to go into certain slots) & the front covers come off & can be replaced with a blank cover(from the one you remove) & be tagged anyway you like).
D1 Driving light or rear wiper switch
D2 cruise control switch

They arent that expensive.

Cheers.

I went through a similar exercise with original Disco momentary switch(es) for reversing/work light and spots using the Jaycar latching relay. For a high current application the latching relay can drive another automotive relay. You can find a simple circuit in siliconchip.com.au May 2010 - circuit notebook. Uses the Jaycar latching relay, with a couple of diodes, resistors and capacitors. Cheap and the relay only draws current when being switched ie/ momentary

Lets say I wanted to do a similar thing to this thread - using momentary swirches - one in dash and one at rear of vehicle - driving a rear work light. What would I need and how to wire it ?

It would need to be able to be switched on AND off from either or both switches.
(that is, ON at dash then OFF at dash or ON at dash then OFF at rear or...)