Hi guys,
I'm trying to make a small timer circuit for the indicators on my motorbike. I've made the circuit up on a breadboard and it works perfectly. The only issue I have now is that the trigger has to be low to start the timer but high again for it to turn off. With this being the case I've been using a N/C pushbutton to interrupt the voltage to the trigger.
I have a N/O pushbutton on my motorbike and would like to use a positive or negative pulse to set off this circuit as an Off-delay timer (pulse, on for 10 sec and then switch back to off as the relaxed state).
I don't want to use a bulky relay and the N/C contact on it to do this and I can't change the switch to a N/C.
Is there a small component I can add to the attached circuit to do what I want?
Regards,
Mick

 

Connect a resistor from + supply to trigger & NO SW from trigger & ground.

 

This should do what you want.

 

This should do what you want.

Seems more complicated than it needs to be.
Just use the circuit that Bernard suggested.

 

As said, put your switch across pins 1,2,,,

select the values for R1 C1 to give your time delay

https://www.google.co.uk/search?q=5...AUIBygB&biw=360&bih=512#imgrc=KQ6Qp9qpnm78bM:

 

As said, put your switch across pins 1,2,,,

select the values for R1 C1 to give your time delay

https://www.google.co.uk/search?q=555+monostable&client=ms-android-sonymobile&prmd=ivsn&source=lnms&tbm=isch&sa=X&ved=0ahUKEwihj8r1--7PAhVhF8AKHQr9CLsQ_AUIBygB&biw=360&bih=512#imgrc=KQ6Qp9qpnm78bM:

Thanks heaps for all your help guys! That was the simplest fix ever. I've soldered up a prototype board this afternoon and hit another snag though. Being for a indicator system I have made up two of these circuits side by side and just connected the pos and neg feeds together and the light comes on with the signal from the button but immediately switches off when the button is let go. I assume this is either due to connecting the two circuits together or my trying to solder a tiny prototype board with a non-electronics soldering iron. I've checked over the circuit a few times and can't find anywhere I've messed up.
Can somebody tell me if I've this is what would happen with the two circuits connected, due to resistances or capacitance in parallel or if it's more likely my soldering job just sucks?
Also if it is the former, can I split the circuits using diodes or something?
FYI when I bread-boarded the first single circuit this morning I used a 1000uf Cap and a variable 10kohm resistor to get 0-11sec output.
I set both Variable resistors to about 6kohm before soldering them into the circuit.
I've also attached a pic of the circuit below (red and black indicating the links between the two circuits).
Look forward to some more expert advice!
Cheers,
Mick

 

Powering them in parallel should not be a problem.
Do you have one switch or two?
Did you get one circuit to work by itself?
If so then you likely have a wiring error somewhere.

 

Powering them in parallel should not be a problem.
Do you have one switch or two?
Did you get one circuit to work by itself?
If so then you likely have a wiring error somewhere.

Hey Crutschow,
I was just changing the switch and led connections to the other trigger and output to test. I'll have another look over the circuit and try to find the issue.
Cheers for the help,
Mick

 

Powering them in parallel should not be a problem.
Do you have one switch or two?
Did you get one circuit to work by itself?
If so then you likely have a wiring error somewhere.

Hey Crutschow,
I found the problem with my wiring, cheers for the heads up. I'd dripped a bit of solder from Vcc to C1, cleaned it up and voila.
I'm now thinking of a nother thing to try so I can use the same circuit but with 2 555 ICs. I was thinking I'd solder one 555 on top of the other and just bend out the pins for input and output so I can connect them to different switches and relays.
I'd be almost halving the amount of components in one shot.
I'll give it a try next time I get the chance and post the results.
Thanks again,
Mick