Electronic Memory!

[Mukhalled]

Is it connected to something that is powered all the time including during starting the engine? 

No, it's connencted together with the amplifier and they get the voltage from the (electric lighter, cigarette lighter) which is not always powered. I don't want to connect the audio system directly to the car battery because i might foreget to switch off it, then the battery may be "finito"  ;D.

so is there any hope  ??? ;D

 

[audioguru2]

It's a can of worms. A huge cap is expensive. A rechargable battery might not fully charge but might work.

My new car shuts-off the stereo if I open the door with the engine off. It shuts-off after about 10 minutes with the engine off but if I don't open a door (right in the middle of a breaking news report).

My cheap portable CD player charges its two AA Ni-MH battery cells and would work for you.

My portable Creative Nomad MP3 player holds thousands of songs on its 10GB hard drive and charges its four AA Ni-MH battery cells. It would work for you.
I have 3 more of them to fix. Two of them are smashed so I use them for parts and one is nearly like new (about 2 years old) but its hard drive is broken, it needs a special USB cable (but I might have it in a huge box of cables) and it needs a battery.
You wanna buy it after I fix it??? ;D 

 

[Mukhalled]

I can buy a new CD-player to my car but I think it's cool to build my own things  ;D

 

[Alun]

I'm guessing a bit here, but thie 5V rail is probably a low current supply to power the microcontrolers and logic, if you keep it powered then it'll remember where it was even if the 12V rail goes down. You could test my theory by momentarally disconnecting the 12V, if I am right then you could use my circuit with a 7.2V battery and a low dropout 5V regulator for the 5V rail.