Delay in power supply...

[navveed]

ok, I've installed a dvd player in my car, however when i turn the ignition ON, the dvd player turns on too and starts loading the cd but then i have to start the car and as i do that, the dvd player turns off in the middle of loading the cd which i think would damage the dvd player. (cars electronic circuits are designed in a way that when you start the car, power supply to all the axuliaries is switched off in order to give more power to the starter motor, once the car has started, power supply to the auxliaries is resumed). When the car starts, the dvd player starts again. So basically it starts twice, once with the ignition and then when the car has fully started.
What I want is a delay in the power supply (around 5-10s) that is from the 12v battery of the car, so that when i turn the ignition on, the dvd player does not turn on immediately but waits for 5-10s so that i can start the car. In this way, the dvd player does not have to turn on twice but only once and that is when the car has started. The circuit has to be simple, the dvd player does not have to detect if the car has started yet or not, if the ignition remains on for more than its delay time thats 5-10s, the dvd player should start without waiting for the car to start. All i want is a delay of 5-10s from the 12v when the ignition is turned on.
Would a simple resister in series with the 12v power supply do the job. Any help would be appreciated.

 

[MikeMl]

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Would a simple resister in series with the 12v power supply do the job. Any help would be appreciated.

Hi Naveed,

No, the solution needs to be more complicated. The simplest thing I can think of would use a resistor, capacitor, Power FET, a 12V relay, and a diode. Could you round up the parts and build it?

Do you happen to know how much current the player draws while it is starting up? If not, do you have a Multimeter so that you could measure it?

 

[navveed]

Hi Mike,
Thanks for the reply. The current is 12A. I can buy the parts however if you could please draw the circuit including the required part values, that would be great. thanks again.

 

[MikeMl]

Hi Mike,
Thanks for the reply. The current is 12A. I can buy the parts however if you could please draw the circuit including the required part values, that would be great. thanks again.

Are you sure about the 12A; that seems awfully high for just a DVD player. I'm guessing it should be ~2A. This goes to what sort of relay you will need. I guess you could use an automotive 20A Bosch style (headlight relay/horn relay). I'll work on the timer circuit tonight.

 

[MikeMl]

Here is about the simplest delay timer I know how make.

 

[navveed]

Hi Mike,
first for all thanks v.much for the circuit, i will work on it and build it soon. The current 12A is basically in its specs plus there is a 12A fuse in it too. So I thought it must be 12A. Any way I think your suggested relay (lights relay) will be perfect for it. If i get stuck will have to contact you again, hope you wont mind. thanks once again. best regards.