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#1448882 - 28/07/08 04:56 PM

Building a gps into the car...automatic powerup?

Big Frost
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Registered: 07/06/08
Posts: 97

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Ok, so im happy with my head unit, dont want to change it...im also happy with my plug and play gps.

My problem comes with my custom built center console...i want integrate the normally removable gps into the console...no thats not hard as far as power supply and physically fitting it into the console, but id like it to power on automatically when i start the car, and power off when i stop it.

Now upon taking it apart, i soldered wires onto the button terminals, and noticed that a tap of positive electricity turns the unit on, and a tap of ground turns it off.

i would normally use a relay, but i dont think its safe to have constant power running to that terminal, especially when its not needed...plus it wouldn't account for turning the unit off.

so does anyone know a way to do this? the headrest monitors work the same way, and id like to hook them up to a switch...but any info you guys have on this would be helpful.

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#1456398 - 07/08/08 09:50 PM

Re: Building a gps into the car...automatic powerup? [Re: Big Frost]

Big Frost
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Registered: 07/06/08
Posts: 97

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nobody?

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#1456427 - 07/08/08 11:10 PM

Re: Building a gps into the car...automatic powerup? [Re: Big Frost]

keep_hope_alive
Snooch to the Nooch
SD I chew on Mike Tyson's ear

Registered: 24/04/07
Posts: 8658
Loc: Quad Cities, IL

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hmmm, i hadn't seen this post before now. you'd need a momentary contact closure to simulate pressing the button. that can be achieve with a latching relay configuration. off the top of my head (and without actually drawing it out) i think two or three 5-pin relays, a diode, a capacitor, a NPN transistor, and a resistor. the capacitor, resistor, and transistor provide the delay. maybe use a potentiometer instead of a relay to provide an adjustable delay (i.e. adjustable discharge of the cap). the cap and resistor would be in parallel with the base input to the transistor and ground. the diode would just be in series before the cap/resistor to control current direction.

the ignition voltage would trigger the first relay which would start the contact closure for pressing the button in and the delay circuit would then latch the relay back to it's previous state to simulate letting the button go. the issue you'll have is with the two ignition signals (due to losing ignition voltage when starting the car). you'll need a delay in there to prevent the circuit from losing power when starting the car or prevent the circuit from starting the sequence until ignition voltage is maintained for a period of time.

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#1456434 - 07/08/08 11:25 PM

Re: Building a gps into the car...automatic powerup? [Re: keep_hope_alive]

gibby
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Registered: 17/02/08
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Loc: Pittsburgh, PA

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Not to hijack but that would work for any type of unit that has a push-button turn-on?

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#1456595 - 08/08/08 07:25 AM

Re: Building a gps into the car...automatic powerup? [Re: gibby]

keep_hope_alive
Snooch to the Nooch
SD I chew on Mike Tyson's ear

Registered: 24/04/07
Posts: 8658
Loc: Quad Cities, IL

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most likely. you'd have to desolder the existing push button (rendering it useless), then wire into it's place with your new circuit. you could build in a new manual push button that controls your circuit.

may be possible to replace the relays with transistors (to save money and physical size).