Thread: Valet Switch HELP!

Originally Posted by Nickwell24

I want someone to tell me I did this correct. Power (obvious) ground (obvious) but Acc (is this the wire i'll run to my Computer?)

it sounds like you're using a lighted switch. lighted switches work the same as any other SPST switch, but they also have a ground lead (to ground the bulb). so to answer your question... yes, the switch's "ACC" lead goes to your computer.

NOTE: if you want to use it as a valet switch (as opposed to a main power switch), then your main power should go through a relay switched on/off by your car's ignition or ACC line. you can then install a switch on the IGN or ACC line to act as your "valet" switch.

this is what I mean:

Originally Posted by skystitt

why not just wire the power to your ignition? i'm new to this but it would just be like audio right? or is there a remote wire? is there a memory wire so you dont lose all your stuff you have saved?

you should NOT power anything directly off the car's ignition or ACC wires. these wires are not 'general use' power wires, they are specific circuits for specific purposes. the wires and fuses are large enough to power what came with the car from the factory. if you add things (like a carPC) then you need to run your own power wires to the car battery to power them.

you can use the IGN or ACC wires as a signal wire to control a relay, but you should never power any device directly off the car's IGN or ACC circuits.

Originally Posted by Nickwell24

how do you wire a relay, and how exactly do relay's work

a relay is basically an automatic switch. it uses an electromagnet to open/close a circuit that would otherwise have to be opened/closed manually by flipping a switch, pressing a button, etc.

with a relay, you can control a high current circuit (carPC) with a low current circuit (IGN or ACC). in this case, the IGN or ACC line will be used as a 'signal' wire. it is not directly powering any device, it's only providing a small amount of current to power the coil which will close the circuit (automatically "press the switch").

a standard bosch style relay has 4 or 5 leads, numbered 30, 85, 86, 87 (5-lead versions also have an 87a). two of them are for the coil (86=power / 85=ground). 30 is the high power input (car battery) and 87 is the relay switched output in the 'closed' position (on 5-lead versions, 87a is the switched output in the 'open' position). when you apply low power to the coil, it physically pulls the internal switch to 'close' the high-power circuit (connecting 30 with 87). when no power is applied to the coil, then the high-power circuit is left 'open' (on 5-lead versions, 30 and 87a will be connected).

wiring your main power through a relay will allow your car to automatically switch power on/off to the PC just by turning the key. (mechanical relays are cheap. they only cost about $5-$10 at an autoparts / electronics store)

Think of the future....

If you get hooked on this like so many of us, you will be glad that you did things as well as you could at the beginning.

I is really easy to carefully plan a hole drilled through the firewall of your car to run the power cable. Best Buy and such have install kits that come with large gauge cable, intended to be connected directly to yr car batt through a fuse:
http://www.bestbuy.com/site/olspage....equestid=55928
http://www.partsexpress.com/webpage....ctGroup_ID=731


There are firewall grommets to pass the cable through, then you can give it a squirt of silicone caulk for good measure.

The kits come with a power distribtion block, that once screwed in a location of your choosing, has several output connections for our carpc, screen, amps, whatever...

12 volt power is a big issue and should be done as best as you can. It's one thing I did right the first time. A car fire, or even a little smelly smoke really puts a damper on the fun.

blessings and good luck!