Constant 12 volt sources (+) (dimmer?)

[Tiki2777]

I have some new gauges and know i can use the cigarette lighter for ground and switched 12 volt (+) source. I am not sure, but i have heard that the dimmer is a constant source. Is this true, and what are other constant sources?

 

[steve]

No the dimmer output isn't a constant 12v source. It's variable which is why it's able to dim.

The FSM has a list of which circuits at the fusebox are connected to the battery (constant) and which are switched.

 

[mitsu-luver]

I have some new gauges and know i can use the cigarette lighter for ground and switched 12 volt (+) source. I am not sure, but i have heard that the dimmer is a constant source. Is this true, and what are other constant sources?

You'll want to hook it up to a "constant source" which is really just called Direct Current. You don't want to hook it up to a variable voltage source because the Voltage regulator (turns 12v into 5 or 3.3v) inside the gauge needs the full voltage. The only way you should be able to dim them is if that's a feature that came with The gauge, which im sure it did? If not Its just full brightness.

 

[Tiki2777]

No the dimmer output isn't a constant 12v source. It's variable which is why it's able to dim.

The FSM has a list of which circuits at the fusebox are connected to the battery (constant) and which are switched.

Whats FSM?

 

[steve]

Whats FSM?

The Factory Service Manual. Something every DSM owner should have for their car.

 

[1990AWD]

Wouldn't you want a switched power source for you gauges? That way they're not always on draining battery.

 

[dexterholland04]

Wouldn't you want a switched power source for you gauges? That way they're not always on draining battery.

Correct, I believe he just misspoke. You would want your gauges wired up to a switched, 12V source. If all your gauges are mechanical, you could wire them in to the dimmer; since the only the lights in the gauge are the only thing that requires power. If you have digital gauges, then you would need the full 12V to the gauge from a switched source. Mitsu-luver is correct in the sense that a digital gauge regulates the 12V from the car down to 5V for any input/output to the gauge and also regulates 3.3V as well for the digital logic.

 

[mitsu-luver]

Wouldn't you want a switched power source for you gauges? That way they're not always on draining battery.

Yeah of course, I thought they were talking about something else. When I hear switched power source I think of a pwm power supply oops.... I work on electronics more than cars now but yeah that's kind of obvious...

 

[steve]

Wouldn't you want a switched power source for you gauges? That way they're not always on draining battery.

Typically, but peak holding might require a constant backup source in addition to switched.

 

[1990AWD]

Typically, but peak holding might require a constant backup source in addition to switched.

Oh, makes sense. I learn something new every day.

 

[Tiki2777]

Oh, makes sense. I learn something new every day.

The reason for the constant source is one of the wires holds memory for the color the gauge is illuminated, There is a switched source wire that lights the gauge, thats why I need a constant, for the memory, otherwise a switched would work

The Factory Service Manual. Something every DSM owner should have for their car.

Looked in my fsm on my ipod in ibooks, but i really could not find much on the actual fuse box in the cabin area on the driver's side. Do you know where i could find more information on constant sources from the fusebox or elsewhere? Thank you so far because it has helped quite a bit.

 

[steve]

Looked in my fsm on my ipod in ibooks, but i really could not find much on the actual fuse box in the cabin area on the driver's side. Do you know where i could find more information on constant sources from the fusebox or elsewhere? Thank you so far because it has helped quite a bit.

It's called the junction block and under the multi-purpose fuse list you'll see which fuses are connected to the battery and which are switched along with when (IG1, IG2, ACC) then when you look at the power distribution diagram you'll see when they go and the wire colors.