Car Headlights, PWM

i am an idiot wrote: For the times that the PWM is at 0, the diode keeps the cap from trying to keep that voltage up. It will use all of it's capacitance to keep the relay energized.

Got it. Should I be concerned that excessive capacitance may keep the relay pulled in after the computer has signaled for the high beams to be off?

The time will be minimal.

i am an idiot wrote: The time will be minimal.

Are we talking minimal like on the order of milliseconds? I only ask because with the way the system functions, being pulled after the signal is gone can get counter-productive. If I find the time to be excessive, can I keep dropping the capacitance down to reduce hold-in time? Kind of "fine-tune" it until I achieve an optimal balance?

Yes you can reduce capacitance to shorten the hold time. I do not remember how long a 4700 will keep a relay energized, but I am thinking around a second.

i am an idiot wrote: Yes you can reduce capacitance to shorten the hold time. I do not remember how long a 4700 will keep a relay energized, but I am thinking around a second.

Yikes. That is way too long. When you are talking about dimming high beams for oncoming traffic, a second is like a lifetime. I guess I'll have to play with capacitance. I ordered some 220 uF caps, too. Will that be enough? If I'm not mistaken, I only need enough capacitance to keep what I will call the "effective voltage" above the hold-in voltage of the relay's coil, correct? Any guesses at how much capacitance will be needed?