Hi guys..
Was browing through silliconchip and got wind of apparently how easy it is to build a turbo timer.
Anyways, the circut seems to be based about a 555 operating in one-shot mode, trigger would likely be the zero pulse present from the tachometer wire.. Correct me if i'm wrong, i'm just speculating.
just FYI a turbo timer is supposed to be there to "take over" after you have driven and turned the car off to leave it to cool down the turbo bearings so that the oil doesnt' cake up and choke the turbo.
Anyways.. I was planning on a very non-descript one. NO fancy timer display, just a few preset values.. say 30 and 60 seconds of running. Just want to be able to chuck a black box under the dash with no prying hands to play with it.
But if it's not too hard to implement a timer display, I supposed it'll need another IC to control it, it would be a good idea.
Here's a rough look at the interior of a simple turbo timer, slectable at 1/3 minutes. frankly, it doesn't look like much work. Don't bother reading.. the site's in Japanese.
http://www.yagisawa.net/noah/pw_window/index.html
Anyways, to recap.. where do I start with for a trigger input? It's supposed to detect the moment the car switches off and takes over immediately.