I have the following 12 volt automotive circuit setup and working to trigger about 60 seconds of power output to a relay on output pin 3 of the 555 Timer chip.
This setup allows a negative 1 second input pulse to turn on a the 12V automotive relay for about 1 minute.
The 2nd requirement of the circuit is to also trigger the 60 second output of the 555 Timer to fire once the 12 Volt Ignition wire changes state from 12 volt to off/ground. While I can easily make it turn off by sensing ground, the timer needs the input to be momentary, because latching the input to ground keeps the 555 Timer's output high for the duration of the ground input.
Any suggestions how to send about a 1 second ground pulse when the ignition changes state from 12 volts to ground?
I know I could add a 2nd 555 Timer circuit to accomplish this but I am trying to keep the circuit complexity down as well as keep the standby current as low as possible.
Thank you for your feedback.
This setup allows a negative 1 second input pulse to turn on a the 12V automotive relay for about 1 minute.
The 2nd requirement of the circuit is to also trigger the 60 second output of the 555 Timer to fire once the 12 Volt Ignition wire changes state from 12 volt to off/ground. While I can easily make it turn off by sensing ground, the timer needs the input to be momentary, because latching the input to ground keeps the 555 Timer's output high for the duration of the ground input.
Any suggestions how to send about a 1 second ground pulse when the ignition changes state from 12 volts to ground?
I know I could add a 2nd 555 Timer circuit to accomplish this but I am trying to keep the circuit complexity down as well as keep the standby current as low as possible.
Thank you for your feedback.