PC ignition switch mod

[crazyknight]

Hey everybody,


I started working on a project for my father-in-law and I am missing an article I had seen somewhere showing how to use a key ignition switch to start a computer. Has anybody else seen it or maybe know where it is. Thanks...

[cobalt6700]

yup its right here:

http://www.modfatha.com/ma_military_switch.html

go to the forums if you have any problems. there is only the 3 of us on it!

gaz

[crazyknight]

That's not it but thats pretty cool too! I was looking for a guide I had seen using a keyed ignition switch from a car; put the key in, turn it, and the 'puter comes on. I love those military switches just haven't come up with a project for them yet. Oh and yeah, it is pretty quiet over there...

[Starbuck3733T]

Same basic principle though. The ignition switch needs to use the momentary position on the key mechanism, the one that's usually used to turn on the relay to crank the engine (turn the starter). Find the terminals for that position (or terminal, if the other is shared) and solder it to your ATX power on cable. Cake.

[crazyknight]

Cool thanks! I didn't remember there being anything to complex about it but I figured I should ask just to make sure.

[cobalt6700]

whats the paperclip trick btw?

[zittware]

I can see it now... for the next car-based mod MNPCtech does; I can already see an ignition switch incorporated.

[bobvillain]

Same basic principle though. The ignition switch needs to use the momentary position on the key mechanism, the one that's usually used to turn on the relay to crank the engine (turn the starter). Find the terminals for that position (or terminal, if the other is shared) and solder it to your ATX power on cable. Cake.
with that setup, will it do a soft-off when you turn the car back off? or does it only use the momentary position when turning on?

[Starbuck3733T]

if you wanted to soft-off the system with the simple hookup, you'd just "crank" the key again. to force a shutdown, crank it for 5 seconds. You could set it up with something more complex, but it might require some electronics know-how that you may not have...

Hey mnpctech: another kit product for you to put up as part of the pro-line, pro ignition switch??

[crazyknight]

The reason I was concerned was the fact of how the switch appears to work. Turn it all the way to start the car and then it goes back into another position while the car is running. A third position turns the car off. It seems to me that the second position (while the car is running) is not in a switched off position and if it is, what does the off position do? I know this is confusing and I am probably over thinking it but hey, it does sound neat :cool:

[ỒĊBłůē]

A car's starter circuit is far more complex than that of your PC.

Your car needs latching contacts on the ignition switch to energise certain circuits, along with the momentary contacts purely for starting. Without having those other circuits, the car won't start (more or less how immobilisers are used).

Your PC only needs the momentary contacts (unless it's an old AT style system) to start it - a second 5-second press of your Power button should shut it down.

By fitting an ignition switch, you're simply replacing the momentary Power button with the momentary 4th position of the ignition switch.

[Pug]

whats the paperclip trick btw?It's where you jumper the green wire in the ATX power lead to a black ground to fool the PSU into thinking that there's a motherboard attached (it won't power up otherwise).
I seem to recall that you have to have a load present on the 5V rail to avoid damage to the PSU but I could be remembering wrongly.

The reason I was concerned was the fact of how the switch appears to work. Turn it all the way to start the car and then it goes back into another position while the car is running. A third position turns the car off. It seems to me that the second position (while the car is running) is not in a switched off position and if it is, what does the off position do? I know this is confusing and I am probably over thinking it but hey, it does sound neat :cool:I was going to rig one up myself with the first position powering a pump and the second doing the momentary contact for boot but I haven't really found a suitable switch yet - all the average car ones seem pretty bulky and I don't have access to a decent scrapyard locally.
Guess I'll make one eventually if I do end up using one. :dremel:

[brandon mitchel]

Its better to have a car switch to start a car. Because when your car incurs a short circuit you can easily prevent it.