There are a lot of people asking about the startup option of the shutdown controller lately (www.mpegbox.net). Basically, if you want the unit to send a pulse when the Aux line goes high, you have to add a cap to the design. The only problem with this is it sends a pulse every time the ignition line goes high.
Here is the MOD:
There is a row of caps going away from the relay. (Medium, Large, Small) You add a 10uf capacitor in the holes that are not
used right next to the small one. The plus terminal goes in the square hole. The value is 10uf.
The only problem is that this sends a pulse every time the aux line goes
high, even if the first timer didn't expire.
Set the main timer to 8 minutes.
Drive into gas station.
Turn off car, computer stays on.
Come back in 4 minutes.
Turn on ignition, pulse gets sent, computer turns off.
You are now driving around with a computer that is off.
You turn off the car, turn it back on and every thing is normal again.
If you don't care about the gas station model or you are just using the SDC so it doesn't kill your battery, maybe this is ok for you.
If you can use the AC Power loss feature of the motherboard, do it and don't mess with the capacitor for the "startup option"
MPEGBOX - Plexiglass Computer