I bought one of these cheap off ebay DEI 528T Pulse Timer:
Adjustable pulse length. I paid $9.90 with shipping.
Yup the guy called beakmyn who posted the link
I made a circuit almost identical to yours (except with a diode, similar to Mike Carr's design,) and it has a problem with the cap discharging and sending a second pulse a minute or two later. Let me know if yours works. I even spoke to Mike Carr about it and he admitted that he had no idea, he just copied the circuit from someone else himself.
What is the blue thing above the resistor in your design?
Your controller doesn't send a second pulse and shut down the computer a minute or two after starting? Do you mind if I ask the exact specs of the parts you used? My circuit is only half that design since I only need the startup pulse, but I think it should work anyway.
its just a tes probe ( its a screenshot from a circuit simulator)
www.digital-car.co.uk - The UK CarPC Forum
I have no second pulse on the circuit as far as I could test.
Parts are :
-3x Scrack T7NS5D1-12 10A@28VDC Relays
-2x 1000µF 25V El. Capacitors
-standard diodes and resistors
Update: the unwanted pulse was coming from the Mucha controller, not my startup circuit. I didn't have the time to futz with it, so I replaced the whole mess with an ITPS (modified to bypass the regulator) and everything is working great now. I really wanted the flexibility that the Mucha contoller offered, but I've had nothing but problems with it.
How about a circuit that pulses once when a switch is closed, and then pulses twice when a switch is opened? It could operate on either 12V or 5V.
The reason I ask is because I think the Lilliput (in pieces at the moment) cycles through the VGA, Composite 1, and Composite 2 video inputs with each input switch closure. This circuit would make it possible to implement automatically switching to a rear camera input when reverse gear is engaged, and back to VGA when it is disengaged.