I have a 12v DC (continuous) source that holds an exhaust brake on a diesel pick-up closed. The new exhaust brake requires a momentary 12v DC pulse. Is there a simple way to convert a continuous source to momentary?
A capacitor in series with a relay coil would work. That's about as simple as you could get. How long does the momentary pulse need to be? How much current does the exhaust brake draw?
Thats what I figured, just wanted a confirmation.
The draw is only the coil on a 12v automotive solenoid. It needs to pulse about a 1/2 second.
12v pos. to coil, 12v neg to capacitor then ground?
Yup. The size of the capacitor will depend on the relay. With a typical 150hm: automotive relay coil, try 4700uf or so. You may need a diode across the coil to prevent the relay from clicking again when the voltage disappears.
You should always have some margin for error. Choose a 16V one or higher because the charging system on the truck typically will float the battery up around 14.2V when the engine is running.