Thread: Wiring Flow Diagram, please help fill in blanks

You're going to want to run external power to the hub if you want to prevent potential issues, especially if you're going to have a slim DVD player hooked up to it. Also, in your diagram you're missing a data line (USB) from the touchscreen to the laptop.

Originally Posted by Nickwell24

what extra wires would i have to run for a relay? You said there are two extra wires, my guess would be Acc and Ign?

close ... one wire is a plain old ground (for the relay coil), the other is a switched power input (for the relay coil). the relay power input should be wired to the ACC or the IGN circuit. the ACC circuit (first key position) is live when the key is in the 'ACC' or 'run' position. the IGN circuit is live only when the key is in the 'run' position.

a standard bosch-style relay has 4 or 5 leads. 86 is the coil power (from ACC or IGN line), 85 is coil ground, 30 is your PSU's power source (car battery), 87 is the switched output (87 and 30 are connected when the relay coil is powered). on 5-lead relays, 87a is the other side of the 'switch' (87a and 30 are connected when the coil is NOT powered. for your setup you have no need for 87a, so just leave it disconnected).

I think I remember from one of your other posts that you wanted to use a lighted switch. if that is the case, then it would only be 1 extra wire (since you would be wiring a ground wire anyways )

Originally Posted by Nickwell24

My main concern about a relay is where i'd put it....

a 30A relay is generally a 1 inch cube... that's it. even with the wires connected it's still only about the size of a single "C" cell battery. you can pretty much hide it anywhere

Originally Posted by Nickwell24

Also with a relay when i turn my car off it sounds like the pc would turn off, unless i put an addition switch infront of the relay which would bypass the relay and direct signal directly to the pc.

with a desktop-type setup that would be true. but since you're using a laptop, it can run off it's own battery. when the relay switches off, the laptop will simply stop receiving power from the car's battery. it would continue to operate with it's own battery until you turn it off (or it's battery dies). if you want to continue powering it from the car's battery without the engine running, then you simply leave the key in the 'ACC' position

What happened to the ComputerGeek Name?

I would suggest that you power your LCD Monitor from the 12VDC output of your power supply. The raw 12VDC from the car's system usually runs about 14.8 with spikes and sags on the line from starting and as other loads are switched on and off. The thought is that the regulated output of your PSU will give you generally better prefromance and life on one of the most expensive components in you system.

Neil

Because i'm using a laptop i'm not using a PSU, i'm running my power battery relay switch laptop power supply.

Fusion, question about a relay, if i have a relay before my switch when my car turns off is it going to kill all power to my switch? I'm guessing this is when the valet switch would come into play by by passing the acc line (relay) and sending power straight to the switch?

Originally Posted by Nickwell24

Fusion, question about a relay, if i have a relay before my switch when my car turns off is it going to kill all power to my switch?

yes it will. if you wire a relay before your switch, then the relay will cut power to anything hooked up to lead 87. you shouldn't put a switch after the relay. remember, the relay itself is a switch, so there is no need to add another switch the the relayed power wire. if you add a switch, it should be on the coil power line (to prevent the relay from switching power 'on').

Originally Posted by Nickwell24

I'm guessing this is when the valet switch would come into play by by passing the acc line (relay) and sending power straight to the switch?

no. the purpose of a 'valet' switch for a carputer is to manually cut power so that a valet driver (or anybody else you don't want screwing with your stuff) can't turn the equipment on. a 'valet' switch is wired on the coil power wire (lead 86). when the valet switch is in the 'open' position (off) then the relay coil will not be powered regardless of whether or not the car is on.

a valet switch should be wired like this:


you could wire an 'override' switch, but I don't really see the point. I can't imagine a scenario where you would need to use the carputer without the ignition key. if you want to use the carputer without the engine running, then just put the key into the 'ACC' position.

IMO, an override switch would defeat the purpose of using a relay in the first place, so I wouldn't recommend it. that being said, if you still want to wire an override switch then you can wire it in like this:

Wow, thanks for the diagrams, it's really nice being able to see what people are actually talking about. Thanks man, the main reason for the switch is because it's about the only way the GF will be okay with me spending 2 - 3 weeks working on this and giving her no attention, because in her opinion the switch "looks cool", worst mistake ever is take a trip to radio shack w/ a girlfriend to buy a switch, they make you buy the "pretty one" so i end up w/ a $5 switch that looks like it belongs in an F-15 rather than a car.

Originally Posted by Nola111

You're going to want to run external power to the hub if you want to prevent potential issues, especially if you're going to have a slim DVD player hooked up to it. Also, in your diagram you're missing a data line (USB) from the touchscreen to the laptop.

Nola can you explain this a bit more? I have 2 hubs that are powered with DC-DC adapters, but I was not sure how to connect them. I was worried that if I connected them to my relay, they would loose power before the PC could shut down or hibernate. So I decided to add them to the 12v rail on my OPUS 320. Was this a wise idea?