I have an Olimex TMS470-P256 dev board (http://www.sparkfun.com/commerce/produc … cts_id=546) and I want to use it in an automotive application. Is it safe to run this board with a simple cigarette lighter connection (i.e. a cigarette lighter plug on one end, a 2.1mm/5.5mm coax power plug on the other)? The board seems to run fine from the 12-14V that is available on the cigarette lighter socket, but the silkscreen on the board says “9VDC” so I’m wondering what risks, if any, I might be taking by using this setup. I’m a software guy and don’t know too much about hardware.
It is dangerous IMO, the voltage can spike when the engine is ON and the input capacitor is only rated for 16V. I would add a cheap 9V regulator like the 7809.
You should have a big inductor to attenuate/absorb the kilovolt transients that last for miliseconds on automotive 12V power. Back EMF from motors and even light bulbs. Today’s cars have less, but it’s still there.
There are SAE specs on this, to guide one who is doing a robust design. A hobby thing, well, if it gets zapped, buy a new one!
