Auto power on a dell laptop?

turboICE · 01-28-2005, 08:08 PM

First post. I did search.

Found this schematic which I would like to use at it should work:

http://www.mp3car.com/vbulletin/show...73&postcount=6

However, I don't know which of the 2 contacts of the 5 on the momentary switch to use. Anyone know the schematic on their momentary switches on dell docking stations? C600 laptop (and actually the port replicator) if that helps.

Also, what type of relays should I use. I assume a normal automotive relay coil wouldn't be activated by the LED power - though I could be wrong.

Scouse Monkey · 01-28-2005, 10:05 PM

why not jsut turn your lappy off. put some probes on 2 legs at a time and then press the button and see what links.

Nomally on momentary switches (the little tactile ones) you get 4 contacts which are set in pairs. You switch might have a common connector eg middle and one pair of normally open and one pair of normally closed. Will take you a few minutes of trial and error to work out how it all works seeing what is connected to what and when.

As for the realy problem - no the led power would not be enough but you may beable to get a logic/led signal activated relay which has a circuit attached. Basically ithinkt his is just a transistor which applies the current ot the relay but i am b no means an electronics expert. The rela circuit you would need can be got from most little electronics hobby stores

turboICE · 01-28-2005, 11:20 PM

You know some people make it really hard on me when I am trying to be lazy, sheez.

OK well go out to the workshop and grab the VOM and a jumper wire, and get the pins on the first try.

Not sure why I always forget about transistors, I get reminded often enough. Yeah that will work.

This is what happens when a financial person tries to do electronics.

turboICE · 01-29-2005, 11:16 AM

Well the voltage on the power on LED is 2v, so USB power makes more sense for that relay. However, having a hard time finding a 5v SPST NC relay. Anybody know a source?

turboICE · 02-05-2005, 09:41 AM

anik321 - tried to respond to your pm but got an error back from the system let me know if you didn't receive it.

As an update the circuit above works.

I have a 12v DC adapter powering up my docking station. It is attached to an ignition on circuit for power.

Using the circuit above when the car is turned on it sends a momentary signal to the docking power switch to turn the laptop on, unless there is already power at the usb port. The laptop's power saving settings puts it to sleep if inactive after a length of time if there is no external power (running on its battery).

The capacitor used is 1000uF and the resistor is 10K ohms.