Basically the schematic is of my startup solution to my laptop (and my whoel power system!).
Relay 1 (manual override switch included) Is to allow power to flow from the battery to the compents when the ACC line is charged.
Now here comes the startup controller...
When power is first applied Power flows through relay 1, and goes into relay 3 pulling it closed and therefore the power pins are shorted together. When the laptop turns on my docking station powers up the ps2 mouse port (5v). With the power comming in from the ps2 port the transistor starts conducting and relay 2 closes causing relay 3 to loose power and opening the power contacts and thus achieving a momentary effect.
Also it works when I turn off the car, and the laptop is still on and I start the car again the power button is not shorted again rather relay 2 kicks in before relay 3 thereby stopping relay 3 from closing. The resistor is there to protect the transistor. The diodes are to protect from reverse voltages and the voltage spike when a relay looses power.
The signal source can be anything such as a status led. I just chose the mouse port as it wasn't being use and easy to get to (no leds ont he docking station). There was a schematic around here that involved placing a relay over the Usb 5v+ to achieve a momentary affect however I had no 5v relays (neither did Dick Smith electronics, even if their website said they did!) and didn't want to loose a precious USB port, so this schematic was born.
It works as I have tested it in the car. But if anyone notices anything wrong with the schematic, or anything that can be done to it or even just to comment on it feel free to post.
2004 Toyota MR2
Modified Intel Xeon E5450 3Ghz Quad Core 2GB RAM 160GB SSD M4ATX Xenarc 700TSV TS Toslink Audio BU353 DiNovo Mini Car2PC ODBII Bluetooth HF 16x2 Character LCD