How to: Automatic startup/shutdown controller for 3.50 dollars in parts

sgtpepperaut · 10-30-2007, 04:53 PM

ok here it is:

USE: this gives a single impulse when the iginition is turned on and then again when turned off. The lenght of the impulse can be adjusted by different capacitor values (1000uF) will give u about 0.5 seconds.

IMPORTANT: the direction in which u wire up the capacitor matters so pay atttention to that!

you need:
2 x standard automotive relayes (2 dollars from local junkyard)
1 x 1000uF capacitor (1.49 at radioshack)

wire it up like this:

e voila...no more pushing buttons....
i was looking for this for quite a while and didnt feel like spending 30 bucks on a controller...hope this helps someone!

before i forget idea comes from: 12v.com and a post in this forum which i cant seem to find anymore lol

BartDP · 11-07-2007, 01:59 PM

And how it works :

12V apllyed to to coil of the first relay (between 86 and 85)
This activates connection between 87 and 30 so current can flow to the coil of the second relay with will load the capacitor.
Moment capacitor if full, potential level between 86 and 85 will become 0 volts and coil 2th relay falls off.
Puls generated.

By take off the 12 volts :
Coil 2th relay (pin 86) connects to ground.
Capacitor discharges via coil
Coil active (87 connected to 30)
Capacitor discharged
Coil falls off.
Puls generated.

Pandaman72 · 11-09-2007, 04:11 PM

I did a similar thing, but it doesn't work as I would like.

When I turn the key to 'ACCESSORIES' the carputer starts up just fine, but if I shut the carputer down while the key is still on, it just starts right back up again.

Also, it won't turn the carputer off for any reason.

Instead of automotive relays, I used smaller relays -

So I guess all I will have to do is figure out which is the normally opened / normally closed pins on the automotive relays and replicate that on my setup.

Thanks for the tip

Panda

andyman · 11-10-2007, 03:29 PM

I looked into this circuit myself.
The problem I see is:
If you turn the car on the laptop switch is closed which starts the booting process. If you turn the car off before windows is loaded then the laptop will not turn off.
Windows has to get up and running in order to perform the shutdown/hibernate request from power button activation.

Pandaman72 · 11-10-2007, 07:07 PM

Quote: Originally Posted by andyman

Windows has to get up and running in order to perform the shutdown/hibernate request from power button activation.

That's not really a big problem though. The scenario you mention would not happen very often, but for the vast majority of time this would do exactly what I wanted, i.e. -

Key On = Carputer start
Key Off = Carputer shutdown

Panda

meddler · 11-10-2007, 07:55 PM

nice simple solution. good work sgtpepperaut

andyman · 11-10-2007, 08:37 PM

Your right pandaman,
Even if it did, it is fixed pretty quick.
Thanks for your input!

alienmanfc6 · 11-21-2007, 09:52 AM

i just want to thank you sgtpepperaut. i have been trying to work on a setup just like this but i had like 6 relays and a bunch of caps and resistors. this is so simple i dont know how i did not think of it. Thank you

kirk78h · 12-03-2007, 10:04 AM

I've used automotive relays before, but I'm a novice with them at best. Since soldering to a power button is out for a lot of us, could a similar setup with relays be used to initiate a short between two wires? If so, this could be used in conjunction with the serial port shutdown solution in the forums (and at carpcstore.com). From the description in the first post, this seems very possible -- I'm just not sure of the connections to the relay. Can anyone shed some light on this one?

Thanks,
Kirk

alienmanfc6 · 12-10-2007, 09:44 AM

I just wanted to say that i tryed to make this and it did not work. I played with it for a while and found that you have to change one wire from a switched to a const. If you do it the way sgtpepperaut has it drawn it will start the computer but will not shut it off. Here is a diagram of how it worked for me. and i also added another relay and capasitor to delay the turn on about 2 1/2 secs to allow the car to crank and start before turning the computer on.

O and kirk78h if you wanted to short two wires on a serial port you would use power wire 1 and 2. when the car turns off it would short these two wires. I would also short then when your car turns on but your computer would be off so i dont think it would matter.

(The relay i added is the one on the left)
(Small correction. the capasitor on the left should be 4,700 not 47,000, sorry)

kirk78h · 12-10-2007, 11:32 AM

Quote: Originally Posted by alienmanfc6

O and kirk78h if you wanted to short two wires on a serial port you would use power wire 1 and 2. when the car turns off it would short these two wires. I would also short then when your car turns on but your computer would be off so i dont think it would matter.

This is very cool. Thank you for the reply. By using this with the serial port, it is a viable solution for laptops and other carputers where you can't solder to a power switch.

Kirk

Roadmaster11 · 01-22-2008, 03:51 AM

I assume that Power button wire 1 and power button wire button 2 refer to the f_panel on the mother board?

anchim · 01-24-2008, 08:12 PM

Quote: Originally Posted by sgtpepperaut

ok here it is:

USE: this gives a single impulse when the iginition is turned on and then again when turned off. The lenght of the impulse can be adjusted by different capacitor values (1000uF) will give u about 0.5 seconds.

IMPORTANT: the direction in which u wire up the capacitor matters so pay atttention to that!

you need:
2 x standard automotive relayes (2 dollars from local junkyard)
1 x 1000uF capacitor (1.49 at radioshack)

wire it up like this:

e voila...no more pushing buttons....
i was looking for this for quite a while and didnt feel like spending 30 bucks on a controller...hope this helps someone!

before i forget idea comes from: 12v.com and a post in this forum which i cant seem to find anymore lol

Could someone please let me know where does the power button wire 1 and 2 connect to on the mobo.
Thanks

anchim

sedtc · 01-29-2008, 08:56 AM

connect the wires to the power switch header on the motherboard. normally, the power button on a computer is a momentary switch that merely shorts the two wires. this simple circuit illustrated here is acting as the momentary switch.

ankitgoenka · 06-29-2008, 12:16 PM

Kindly confirm if the circuit works!
Also what specs of the relay can be used ? would ne 12V relay do?