I just installed a car PC it has a power supply that allows for pulse start meaning it will start the PC as soon as it gets a electric pulse. Now the way I would like it to work is as soon as I press the unlock button on the key Fob it triggers the pulse to the power supply to start the car PC.

The question then is what can I hook the cable up to in the car to get the small electric pulse that happens when the doors unlock and the dome light comes on?

Preferably without running the cable to far from it's location near the passengers side kick panel.

Thanks My car is a 2005 coupe

 

You should probably post in the Car PC section.

 

Trying to find the pulse start location doesn't have much to do with the car PC.It's an electrical question this would be closer related to alarms and remote starters.

 

I just figured that someone in the car PC section might have already figued it out for their setup. Most members don't install their own alarms or remote starters, or have a need for a pulse.

I take it that you need a pulsed + signal rather than a pulsed ground.

 

when you unlock your car do your parking lights or any other lights flash?
if so you may be able to hook it up to those.
Your parking light wire is a red with blue stripe in the drivers kick going to the rear.

 

well you could build a relay setup that draws juice somewhere and triggers off the dome light. I don't know if there's such as a thing as a pulsed relay, but there ought to be. If not, go build you a circuit out of a 555 timer chip to shoot your pulse out from the relay.

However, i don't know that the dome light is the best choice. You'd get the pulse whenever it comes on, e.g. the opening the doors, interior lights, etc. I'd get a copy of the service manual and see how the system disarms itself. If it's something that can be triggered off of (e.g. a specific signal vs a network message... unsure how our cars do this... CAN BUS?), then you can use that to trigger your relay/timer setup. KPierson would be a good guy to ask.

 

Thanks for all the replys

Gilley it does need the pulsed + signal.

TroysG I may try what you said I will look for that wire and try to test it.

Glycerine you are rite I can't use it of the dome light it would trigger a pulse every time I opened the door.

From what I have read on the 12volt forums the pulse for the door lock/unlock is in the door but I will try Troys advice and see if tapping that parking wire if it is not going to have power all the time.

Here is what the manual says.

4.1 Pulse Start Connections
The Pulse Start input can either be an externally applied voltage (ie +5v or +12V) pulse, or a momentary relay contact closure. The externally applied voltage pulse is connected to Pin 1 of J1 using the Blue wire. The momentary relay contact closure is connected to Pins 1&2 of JP1 (see Section 2.2 for location). You can use either or both of these connections to start/stop the PSU.
4.2 Pulse Start Operation
4.2.1 What is a pulse?
Voltage Pulse on Pin 1 of J1
When connecting to Pin 1 of J2, the “pulse” must be a voltage that transitions from 0V to +V, and then transitions back to 0V. The SSC will wait (hang) if the voltage stays high without going back to 0V after the initial transition from 0V to +V.
The value of the +V can be any voltage from approximately +2V to +20V. Typical voltages are +5V or +12V. The value of 0V must be below +.2V or open circuit (ie you could drive this input with a relay that momentarily connects to a +12V source and then provides an open circuit).
The current required to drive this input is very low (milliamps).
Contact Closure Pulse on Pins 1&2 of JP1
When connecting to Pins 1&2 of JP1, the “pulse” must be a low resistance metallic contact closure (ie relay) that transitions from OPEN to CLOSED, and then back to OPEN. The SSC will wait (hang) if the contact closure remains CLOSED after the initial transition from OPEN to CLOSED.
The current passing through this relay is very small (milliamps) so a low power relay can be used

 

Enigma,

I think i just read into what you're trying to accomplish. You want the pc to be booting from the time you unlock so it's on when you drive away?

That true? .... You sure you want to do that?

If i'm offbase, ignore, but wouldn't starting the engine interrupt the power? If you're using a straight tap off the battery, then it shouldn't, but i'd be a lil worried about the psu while cranking...

Also, what about unintentional clicks? How does it handle that? e.g. you accidently hit the unlock in your pocket, PC fires up. You realize it and lock it back, or it auto locks back. Either way, PC is now running. You either a) go turn it off manually (since you have it wired to constant power and the disarm, *not* the ACC wire) or b) it stays on. If it stays on, how does the psu handle the next pulse sent when you unlock the doors again? Do you have protection on your battery to prevent the pc from draining it down all the way?

Most of the DC-DC PSU's i've seen trigger off the ACC wire to wake up/put to sleep a PC. Some folks i've known to put a CF disk in there, strip down windows, and get a boot up time of under 20 secs. That may be a pain, but i'd wait the 20 secs and rely on the DC-DC PSU to handle things cleanly rather than worry about the issues above.

Again, like i said, i'm rusty on this, and you'll find more info at mp3car or carmp3.com (forget which it is), or i could totally be wrong on what you're wanting to do here. Just thoughts