I was thinking about connecting a ground wire to the A and D on the schematic.
And then connecting the B and F parallel to LOW and HIGH connection of my GM motor.
this way the original wiring stays functional and when the Velleman module closes both relays it ground both LOW and HIGH to ground and thus activating the LOW speed of the GM motor.
just wanted to confirm that for other users in future.
but have a another question:
when the car idles or drives very slowly the circuit switches to quick, causing the wiper to stop in the middle of window. also the delay time will be irregular.
a friend with the same car (Chevrolet Suburban) has the same problem.
I have it wired from the IGN (switched power supply) and he has it powered from the wiperwashermotor +12V connection.
something is causing interference I guess messing up the delay.
Any ideas what might be causing it?
I waas thinking in the direction of the HEI ignition. during idle and slow speed the mixture is lean, causing high resistance in the ignition system and thus more intereference??? and this could mess up the IC555?
as promised I am reporting back on how everything works out.
we had a very rainy knight and I drive the car for over an our in total. The circuit had not one hickup. So the rather small 22 uF capacitor seems to do the job.
Well…I am back again…problem wasnt solved completely. yesterday on a warm day the cooling fans turned on. And you guessed it, the circuit went crazy, ratteling like a rettle-snake.
I guess the fans make too much noise for the circuit. I am gonna dig up that bigger capacitor and see if it solves is.