I recently added a small circuit board to delay my car stereo powering up. The idea was to prevent the stereo coming on in the brief period between turning the key from ACC to START and back again. It played havoc with my Bluetooth connectivity.
Anyway, before adding this little board my stereo was more than happy to accomodate temporary voltage drops such as when I turned on the Air Con or a drop in revs.
It seems the new board doesn't like the drops, so when the revs drop (and the voltage from the alternator drops), the board resets and disconnects the output supply and after another 10 seconds the stereo is powered again.
I was wondering if, between the supply and the delay circuit I placed a diode and then a capacitor to ground might help matters.
[SUPPLY] -- [DIODE] ----- [DELAY BOARD] -- STEREO | | [CAP] | | | GND GND
Thoughts? Thanks, Scott
UPDATE: After checking out a few diagrams, I realised the above diagram is wrong. The DELAY BOARD is actually actuating a 12V relay - ie, the stereo is not powered directly from the board, rather the same 12V supply it was on, except now that 12V is switched by the board. So that should remove the possible problem of a voltage drop induced by the board.
+---------------------------+ | | [SUPPLY] ---------+------ [DELAY BOARD] -- [RELAY] | | | [STEREO] | | GND GND
Here's a pic (no schematic, sadly): NB: the pot is to adjust the relay-on delay.