Car alarm starter - turn on accessory?

**ryguy** · 06-13-2005, 02:29 AM

I have a black widow alarm with a pager remote. The remote has both a car starter and an accessory button on it. I would love to be able to hook one of these buttons up to my ignitian so that it would simulate someone turning the key back. My point would be to startup/turn off my computer remotely.

I have an opus in there and it would be great to be able to power the computer on in the morning when i know it will need time to sync music etc.

Is this possible? any suggestions would be great!

**Jahntassa** · 06-13-2005, 02:59 AM

well, you can either have it remotely start the car, and just have the car running with the pc running as well, or if your accessory can 'latch', it can simulate having the car on to the opus and you can do it that way.

**ryguy** · 06-13-2005, 03:05 AM

i don't think the brains of the alarm actually support the remote start (i could be wrong). I'm wondering if the accessory route would be the most logical option. I have no idea how this would/could be done. Just looking for suggestions/help

**blazinlow** · 06-13-2005, 03:09 AM

I had my alarm power up the computer when I remote started it.

There was a wire coming from the alarm brain that got a negative pulse once the car was started.

I used this negative pulse to trigger a relay, which ran to the power button on my carputer. When the relay turned on via the alarm wire, it basically "connected" the two power button wires simulating a button push.

I can give you a diagram if you need. It worked great!

**PatO** · 06-13-2005, 06:35 PM

I ran my negative out into a series of relays to provide a latching signal. Then ran that into a shutdown controller (of my own design, but it would work with any SDC).

4 relays is kind of an embarassment, but I wasn't able to get any solid state circuits to work...

Prior to the 4 relays, I used blazinlow's technique and it worked quite well. The problem is that you always have to feed power to the computer. It doesn't use much power, granted, but it's still power.

**ryguy** · 06-13-2005, 06:42 PM

Would there be an easy way to have my accessory button on the remote simply trigger a 'key turning back' in my ignitian? Because right now my computer turns on when i start my car or turn the key back. To me that would be the easiest...not sure if its possible. Ie press once to turn key back, press again to turn it to the off position?

**PatO** · 06-13-2005, 07:39 PM

Originally Posted by ryguy

Because right now my computer turns on when i start my car or turn the key back.

Let me get this straight -
1) You want to turn your computer on/off via the momentary switch from your car starter.
2) You also want to continue to have the ability to start your computer via the ACC wire (turned on by the key) from your car.

I believe the uSDC in the store will do that. I'm not sure the CarPC's support a push button. But I could be wrong - check the manuals.

I made my own SDC which is similar to what you want. Fun way to get into soldering and circuit design. Cost me around $30 in parts and days and days of research, but it works. Let me know if you want more info and I'll dig up some schematics.

**ryguy** · 06-14-2005, 02:55 AM

Yeah, basically i'd like to be able to have the accessory button on my remote to simulate someone turning the key back/forth in the ignition....

Thanks for your time guys.

**binary.h4x** · 06-14-2005, 07:14 AM

Having an Opus makes it easy.
Use a circuit like this:

http://www.the12volt.com/relays/page5.asp#mtc

use that to control the accessory line to your Opus.

or even this one

http://www.the12volt.com/relays/page5.asp#mtc

that circuit was mentioned earlier.

**ryguy** · 06-14-2005, 04:46 PM

LOL ok, well...i wish i would have paid more attn in electronics class in highscool

I have no idea what that represents =D

Is it a simple relay i have to wire up? So my opus would operate as it does now...except now i could hit the accessory button on my remote to trigger the computer to turn on? If thats true, will the opus still shut off in 20 minutes...or will this keep the opus on (i don't really want that...i still would want it to shut off in 20 minutes as it does now).

Also how would this interface with the accessory option on my alarm? Is it just an output on the alarm? (pos and neg)?

Thanks and I appreciate your patience!