Propably a dumb question ..

**kungmpton** · 04-25-2005, 12:11 PM

Ok, first of all, im quite n00b on electrics so i need sum help please

In attached picture relay passes a pulse of 12v true relay right ?

My question is can this diagram be used to press pc´s power button to
turn it on ? Or how to modify it to use for it ?

**Bugbyte** · 04-25-2005, 12:54 PM

That looks like circuits I've seen that will do startup/shutdown for you. I'll leave it to the electrical genius' to answer but I think that's it.

**kungmpton** · 04-25-2005, 12:58 PM

Originally Posted by Bugbyte

That looks like circuits I've seen that will do startup/shutdown for you. I'll leave it to the electrical genius' to answer but I think that's it.

Yup thats a momentary relay connection indeed, i just dont know how to modify it the way that it connects 2 wires, not actually give out pulse of 12v ...

**Bugbyte** · 04-26-2005, 02:07 AM

You only need a short pulse to signal the PC to turn on. How long does that circuit stay "pressed"?

**strohmrs** · 04-26-2005, 07:00 AM

Terminals 87 & 30 should go straight to the motherboard pin headers for the power switch. They only need to be shorted together briefly. That 12V fused would probably kill your motherboard. The on time of the relay will depend upon the value of the RC network (resistor & cap).

**kungmpton** · 04-26-2005, 07:55 AM

Originally Posted by Bugbyte

You only need a short pulse to signal the PC to turn on. How long does that circuit stay "pressed"?

This layout, ½second which is good for this purpose

**kungmpton** · 04-26-2005, 07:57 AM

Originally Posted by strohmrs

Terminals 87 & 30 should go straight to the motherboard pin headers for the power switch. They only need to be shorted together briefly. That 12V fused would probably kill your motherboard. The on time of the relay will depend upon the value of the RC network (resistor & cap).

Ok this was the information i wanted to know

Thnx

Now i just need to figure out how do i prevent it to press again if i take a leak or sumthing and shutdown engine for a while and then start it again.

-Kungmpton

**Bugbyte** · 04-26-2005, 01:44 PM

Depends. Does your current power supply survive cranking the car? If not, don't bother. If so, put a switch to break the signal line when you stop (that is, normally closed but you would set it to open). That would prevent the signal from being sent to the mobo.

**kungmpton** · 04-26-2005, 02:09 PM

Originally Posted by Bugbyte

Depends. Does your current power supply survive cranking the car? If not, don't bother. If so, put a switch to break the signal line when you stop (that is, normally closed but you would set it to open). That would prevent the signal from being sent to the mobo.

Yeah i have tank battery stuff, no probs with cranking. How do you mean, put a switch ? A Manual switch ?

I was thinking like i need sum sort of time based switch.

Switch stays active after turning of car for ½h and prevents relay system to send pulse to mobo. If line goes active inside ½h interval, it stops counting. IE mobo stays on for ½h after turning of car.