Momentary contact relay

[sc204]

I am new here and have a basic electronics understaning (very basic). I have an electronic device that has seperate on/off switch and start/pause switch. I would like to activate it via a timer, but you have to hit the start/pause switch after turning it on to activate it. The start/pause switch is a pcb type push button. Pushing and holding or pushing and releasing activates it. Pushing again or releasing and pushing again places the device in hold. I can easily wire to the PCB to activate the switch. Is there a cheap momentary contact relay that I could use to mimic the pushing of the switch? This I could hook up to the timer to start and stop the unit.
An internet search did not reveal anything that I could recognize as doing what I need.

Thanks for the help,
Stuart

 

[ljcox]

I'm not sure I understand what you want.

I think you want a timer that starts when the on/off switch is set to on and, when the timer expires, you want to pulse a relay briefly to simulate pressing the Start/Pause button.

Is that correct? If so, I posted a circuit that would do this some months ago. Search my posts. I can't recall the subject exactly but the op wanted a pulse to start a laptop when the power was turned on and another pulse to stop the laptop when the power was switched off.

So you only need the start part. So search on my user name and "laptop".

 

[sc204]

Not quite, i think I need something much simpler. What I am envisioning is that the timer activates the relay and the relay will activate the switch. That part is simple but the problem is that I want the switch to be activated again when the timer goes off. The switch is a momentary contact type. Push once for on push again for pause. So it should work with a double throw relay that opens the connection between throws long enough to register with the switch. I am not sure a standard DP relay is open long enough that the electronics will register it. I may try that though if another simple solution is not available. I was hoping for a relay that would be NO, close and then open again when activated. The same would happen when power is removed.

Thanks again,
Stuart

 

[ljcox]

I still don't understand exactly what you want. A diagram would help.

What I think you mean is that you want a relay to pulse when the on/off switch is set to "on" and to pulse again when the timer expires.

How long is the delay? It may be possible to use a relay timer.

Note that the circuit I posted was for a laptop powered by the 12V from the car electrics. Thus the ICs have to be protected from the alternator spikes. So if your device is not going to be powered from a car, truck or motor bike, then the circuit can be simplified, ie. the 6.8V Zener diodes and associated resistors can be removed.

In short, I need a better explanation.