Secondary trigger signal creation

[james008]

Hi,

I have a twin relay board, one relay I trigger with a sensor signal V1=3.5V.
I want to activate the second relay with a signal V2 that goes high for about 1-3 secs (settable) after V1 goes low.
I was thinking if is possible to do it with few analog components, as I want to keep it as simple and cheap as possible.
Any help with a possible circuit would be appreciated.

Many thanks,
james

 

[BradtheRad]

A 555 timer IC, configured to operate as a 'one-shot'.



The input level does not have to be 3.5V. But it does need to drop low enough to trigger the timing cycle.

The resistance and capacitor values can be adjusted so the 555 will yield between 1 and 3 seconds delay.