constant to momentary + de energise

I've done a good search and read heaps of posts about momentary relay switching but I still can't find my answer.

My project requires a short pulse when 12v (ignition) is active. Activating the switch on my laptop docking station for car PC.

I've built the Constant to Momentary as per the diagram in Relays/Special Applications

I'm not running any voltage across pin 30 to 87 - I just use it as a switch.

This works for the 1st time, but when I turn off and back on again the pulse becomes a constant. I think that the capacitor has not de-energised.

Am I right to think that the resistor is what de-energises the capacitor ? If I remove voltage from the coil for a while (5minutes)  the circuit works as planned.

So if I used a different resistor will that help de-energise the capacitor faster. Do I go for a higher number 10K to 100K or the other way 10K to 1K.

Is there any special direction for the capacitor (stripe side) or resistor (gold band end) ?

Or have I completly missed the idea of this circuit.

With a 10K ohm resistor I wouldn't think it would take 5 minutes to bleed the current off - how big is the cap?

Also, double check to make sure the resistor is brown, black, orange on the color band.

To bleed off current quicker use a smaller resistor (I would cut the value in half until you have reached an acceptable reset time.

Yep the rtesistor is Brown Black Orange - 1K resistance

The cap is 1000 uF.

I just read this post https://www.the12volt.com/installbay/forum_posts.asp~TID~98760~PN~1. Dunno why I missed  it before.

It ends with

you'll need to put a resistor on the input to ground, to discharge the cap after you open the switch, otherwise it won't reset for the next pulse.

how would that be achieved given the circuit I already have

brown black orange is 10k, not 1k.

The cap should be bleeding to ground through the resistor if the circuit is setup as shown, you shouldn't need any other resistors.

How long is your pulse?  You may try going with a smaller cap which will in turn shorten the amount of time it takes to discharge it.

Ah yes by bad. [:oops:]  I meant 10K - Everything is the same as the pic.

I've gone out and bought a range of resistors to try.

Back from the lab.

I found that 220 works well. It takes less than 1 second to discharge the 1K cap.

Now to put it all onto a PCB board.