Gauge Light

[81CJH]

81CJH if what your saying is true then how has everyone else been using the signal from the traction control switch or the ciggy lighter bulb in the past to successfully dim their gauges?

Let us know how the circuit you make up works. maybe you could put a variable pot in there too so you can adjust the overall signal at the start of your circuit as ive been told the brightness of the cobalt gauges are brighter than the dash gauges.

Sorry, missed your post earlier.

In short, I don't know why mine should be different to anybody else's gauges. The fact is that when my gauges were installed they did not dim with the dash lights, and did the weird night light thing on unlocking. Upon investigating further, this is what I found.

The circuit I'm building is also intended to bring the gauges down to the same brightness of the rest of the dash. I haven't built it yet, but I picked up the parts from Jaycar just now for under $3.

Sorry about the crap pics, the GF's camera battery has died so I am reduced to using the camera phone.

As you can see the Black/Ground is connedted to the blue/red wire of the Cig Lite and the Red is connected to the Blue/white.

I ran the red wire to the traction control hole so I could access the POT/Rheostat when I removed the Trac Control Button.

...But you still have to pull out the TC button and adjust the trimpot to dim the gauges, right? I'm hoping to get them to dim automatically with the rest of the dash lights like they should.

Hopefully should have an answer for y'all by tomorrow morning.

...Basketballer Vince: I don't know what seventytwo's pot is, but a 1k ohm potentiometer should do the trick. Jaycar part # RP7504 - $1.75.

Edited 22/09/07 06:48 AM by 81CJH

[seventytwo]

The Trim pot/Rheostat only brings down the brightness to the level of the dash lights. The dash brightness control will then be able adjust all the lights to suit.

I used a 1k pot, but only used the middle and one of the outside legs..

I preferred not to hack the Traction control, Cig lighter has power and a light power source. The Trac button is easy to pull out, so its easier to adjust from there.

[81CJH]

Well guys I'm happy to report that my circuit works a treat.

All up it costs $2.45 and can be built and installed in 30min, if you're handy with a soldering iron and have pulled your dash apart a few times.

I'm yet to take photo's or exact voltage measurements, but here's the parts list and circuit diagram for those who want to give it a shot:

dimmer_circuit.bmp

Parts:

1x 10k ohm resistor (Jaycar Part# RR0596 - $0.38)

1x 110 ohm resistor (Jaycar Part# RR0549 - $0.38) <---- edited: previsouly had 100 ohm (sorry)

1x 300 ohm resistor (Jaycar Part# RR0559 - $0.38)

1x NPN transistor (Jaycar Part# ZT2285 - $1.20)

The resistors are 1% tolerance metal film resistors, and are probably a bit special for the job, but at $0.38 for a pack of 8, I figured it wasn't worth looking for cheaper ones.

The transistor is also overkill given the application, but I chose it because of its size and robust nature. Once again, for a buck twenty, I'm not too fussy.

Output pins on the transistor (text side up): left = Pin 1 (base), middle & tab casing = Pin2 (Collector), right = Pin 3 (Emitter). Also see attached image.

TIP31_Pinout.bmp

Connections:

Negative wire from cig. bulb to Pin 1 (through 10k resistor)

Positive wire from cig. bulb to Pin 2 (through 300 ohm resistor)

Black Ground wire from cig. lighter socket to Pin 3 (through 100 ohm resistor)

Gauge illumination wire to Pin 2 or tab/case (no resistor)

I haven't actually put mine together properly or installed it yet, I just tried it out on some breadboard to make sure it would work. I'll try to do a nice neat job of putting it together & take photos 'n' stuff to make a dinky dye how-to if the moderators would like one.

Please also note that the above circuit is good for a pair of Autometer Cobalt series gauges. Different gauges will require different amounts of power, so you will need different resistor values attached to pins 2 & 3 to get brightness right for your gauges.

Enjoy.

Edited 23/09/07 05:57 AM by 81CJH

[81CJH]

...sorry folks, ran out of edits on the last post.

Here's a new circuit diagram showing a 110 ohm resistor (not 100 ohm)dimmer_circuit.bmp

[XF Falcon]

Awesome mate.

So are the gauges now dimmed to the same brightness as the factory dials? Or do you still have to put a variable pot there somewhere?

[81CJH]

No pot, it dims like it should, cycling through like all the rest of the dash & ICC.

My gauges are now pretty well spot on matched for brightness with the rest of the dash, but like I said, different gauges may be brighter/dimmer than mine.

[81CJH]

P.S. I now have the circuit installed in the car.

[XF Falcon]

awesome mate. I'll be getting my 3 autometer cobalt gauges as soon as some place in the US emails me back.

take plenty of pics mate and put them up, the more the merrier. I like soldering so I might give this a shot

Edited 23/09/07 08:55 AM by XF Falcon

[Basketballer_vince]

any pictures of it installed and off all the parts that you used ?

Edited 23/09/07 01:57 PM by Basketballer_vince

[81CJH]

Just threw up a new topic with all the nuts, bolts & juicy bits.