Hello everyone I installed retractable mirrors on my car and I am trying to figure out how to create a 12 volt pulse so when I start my car they will open and when I shut off my car they will retract and close. So basically what I need is a 12 V pulse when I start the car and another 12 V pulse when I shut off the car.

 

My immediate flash of mind. Will be better ways.
A resistor -capacitor combo.
Car start - capacitor charges.
Car shut off - capacitor discharges.
2 comparators - one HI when capacitor charges above a certain voltage.
other HI when capacitor discharges below a certain voltage.
an OR gate that triggers a 555 in both cases.

 

Are these both for the same control line, or two separate lines?

 

Are these both for the same control line, or two separate lines?

Same line

 

My immediate flash of mind. Will be better ways.
A resistor -capacitor combo.
Car start - capacitor charges.
Car shut off - capacitor discharges.
2 comparators - one HI when capacitor charges above a certain voltage.
other HI when capacitor discharges below a certain voltage.
an OR gate that triggers a 555 in both cases.
Can you provide me with a detailed diagram?

 

Develop on this............



https://www.electroschematics.com/positive-trigger-timer/

 

Same line

Then I assume one pulse is positive and the other is negative.

How long a pulse, and how much current is required?

 

Then I assume one pulse is positive and the other is negative.

How long a pulse, and how much current is required?

Both pulses have to be positive. 1 second should be good enough

 

12 V current

 

12 V pulse when I shut off the car.

if against all odds your engine stops in the middle of the traffic - then at the 1-st order your mirrors retract?

 

Both pulses have to be positive. 1 second should be good enough

So how does the mirror know if the pulse is to retract or open?
Is it just alternate action?
Then you will need some method to synchronize the mirror with the on/off engine signal.

12 V current

How much current?

Do the mirrors have a separate connection to the 12V power, or is it supplied by the pulse?