I saw a post on this forum for something similar, but not quite the same. Here's my issue;
I have some headrest DVD players in the car that the kids love. but sometimes, when the kids (between 2 and 4 years old) are watching a movie I'd like to keep it running when I pop out of the car for a couple of minutes. For instance, when paying for petrol. Obviously I don't want to leave the keys in the ignition, and I normally lock the car for the 3-4 minutes it takes to go pay.
What I'd like is a simple time circuit that can keep power to the headrest DVDs for a short period, say 5 to 10 minutes.
I have key-1 power and also permanent power in the center console where they're wired. I'm guessing what I need is some kind of transistor, capacitor, 555 circuit kind of thing where the circuit takes power from the permanent feed as long as the Key-1 power feed is live. But as soon as the Key1 power is removed it will keep drawing power from the permanent feed for a few more minutes. Preferably tunable to between 5 and 10 minutes.
Ideally, a pushbutton or switch that disables the circuit or simply shorts the timer to zero would also be useful if I'm home and leaving the car completely. Obviously, I don't want it to be drawing power in the off-state if I can help it.
Well that's the limit of my not quite passable O-Level electronics grade knowledge exhausted. I believe I could solder one together from components if I knew what to build but other than that I don't really know where to start.
Is there anyone in this forum with enough electronics knowledge to cig-packet sketch a workable circuit for me that would do this? Ideally, an off-the-shelf kit that could be tweaked would be ideal.
many thanks