Hello festive chaps...Ive fitted 3 Stack gauges to my pillar pod and they have built-in LED white lights but they are far too bright:thumbdown: I cant wire them into the dimmer system as then the speedo lights become so dim i cant see them so my question is can i put some kind of a resistor in-line to reduce the brightness of the gauges??? and what value will that resistor be???.

Hey znut

 

are your guages same as mine? I just took them off to have a look - see pic below (obviously guages are upside down in pic)

 

The top one (boost) has red/black/white wires

 

The middle one (fuel mixture) has red/black/grey

 

the bottom one (baterry voltage) has just red/black

 

It seems fairly obvious the red is 12V, black is 0v and the grey/white wires come form the sensors for boost and fuel mixture

 

That means they don't have a separate feed to built in LEDs and dropping the voltage on the red wire may well dim the guages but certainly the Battery Voltage one would read wrong and probably the other two as well

 

I've got the guages on the bench now just having a look what can be done to dim them yet still have teh guages working properly

 

dicky

Hmm OK the problem I have is I can't see anyway to get these guages apart because the front bezel is formed around the outer casing so I can't ge tto the internal wiring and the illumination circuit itself

 

Therefore when you reduce the voltege supply to dim the guage on the red wire it also affects the voltmeter. It probably has some effect on the boost and fuel mix guages though i can't test this without attaching it all to the car which I'll probably try tomorrow

 

Here's the circuit diagram.

 

The LM317T is a variable voltage regulator that is used to power the guages

 

When the sidelights are off the output from the LM317T is set by the two resistors 390r and 3k3. These values have been chosen to allow 12V to be supplied to the meters - threfore they have full brightness

 

When you turn on your sidelights this also supplies voltage to transistor TR1 via the 10k resistor

 

The transistor turns on and connects the variable resistor VR1 to the voltage regulator. This alters the voltage supplied to the guages and so the brightness. You adjust VR1 to set the desired dim level. I used a 10K variable resistor as that is what I had around, but all the voltage adjustment happened towards one end of the resistor being turned, so I would suggest a lower value, say 4k7

 

You only need to connect to two of the legs on the variable resistor (the middle one plus either of the end ones). The arrow on the symbol for VR1 is the middle leg

 

The transitor could be just about any general purpose NPN transistor. I used a BC337

 

It only takes a few components to build the circuit and all these parts are available from maplin quite cheaply.

 

 

 

I took a photo of the LM317T and BC337 transistor so you can see which leg is which

 

 

The video shows the circuit in operation

 

Sorry that's the best I can do unless someone can figure out how to dismantle the guages without destroying them

 

dicky

Edited December 27, 201212 yr by dicky96

Great info Dicky...not the same as mine but now i have a resistor value to work with...thanks for your help

I've built it on a very small piece of veroboard

 

I used some components of different values as they are not critical and I just used what I had lying around. In particular I used a 6K8 resistor instead of a 10K one nad also a 0.047uF Capacitor instead of a 0.1uF

 

Here are the photos

 

It's small and narrow enough to glue to the inside of the pods holding the guages

 

Don't mount it by the metal tab on the LM317T - it's connected to 12V !!

 

 

Fitting

--------

 

Cut the red wire feeding power to the guages.

 

Connect the cut end of the red wire (feeding the power in) to the red wire in my photo below

 

Connect the other cut end of the red wire (feeding the guages) to the orange wire in the photo below

 

Cut the black wire going to the guages. Connect both the cut ends plus the black wire coming from my circuit all together

 

Connect the green wire from my circuit to your side lights +ve

 

Turn on the side lights and adjust the variable resistor for desired dim level

 

Turn the side lights back off and you are back to full brightness

 

The guages probably won't work properly when dimmed (certainly the voltage meter does not) but at least you are no longer dazzled by night

 

Rich

^^^^^^:bow::bow:

FAO Dicky...it seems your into your electronics mate,found this for you and others who play with resistors:thumbup1:

http://www.ealnet.com/m-eal/resistor/resistor.htm

When I did my City & Guilds (remember those?) in electronics we had this little nursery rhyme

 

 

 

That was 'Acceptable in the 80's' even though we had one or two ethic folks on electronics course, and personally I'm still fine with it, but then of course the PC numpties got involved so it changed to Bill Bloggs Raped Our Young Gladys Behind Violets Garden Wall as a way to emember Black (0) Brown (1) Red (2) Orange (3) Yellow (4) Green (5) Blue (6) Violet(7) Grey (8) White (9)

 

 

Oh BTW the new dimming guages look great (will put some pics up tomorrow) but they dont work while dimmed and that bugs me. If only i could get into the damn sealed up things - so I need a really mechanical engineer to advise here then it will be perfect

 

dicky

Edited December 31, 201212 yr by znut
Sorry Mate,ime fine but it could offend people.

I did some gauges a while back that were sealed, the rings/bezels were sort of crimped on, so eased the edge up bit by bit till it came off, any dents in the metal ring is on the back so is covered once in place, might be worth a try.

I did some gauges a while back that were sealed, the rings/bezels were sort of crimped on, so eased the edge up bit by bit till it came off, any dents in the metal ring is on the back so is covered once in place, might be worth a try.

 

These were mine weren't they Graham, expect so and he expertly changed the colour from white to blue :cool3:.

 

And Rich you're basically making up something like this ?

 

http://www.ebay.co.uk/itm/Universal-Daytime-Runing-Lights-Lamp-DRL-Module-Relais-12V-LED-R87-Car-Auto-/320980050640?pt=UK_Other_Clothing_Protection&var=&hash=item4abbe6e2d0

Ok update....my mate who is all there with this type of stuff has made me a 3 pin pedometer with 1 resitor and 1 transistor with a full working range from off right up to full brightness and it works perfect. He told me to try it and see iff it gets hot which it does not so he got the values spot on,now i know it works on 3 gauges with what looks like 2 leds in each i with go and see him to ask for a detailed component drawing and post it on this thread..this mod does not effect the working of the gauges in any way just the backlighting:cool3:

That would be interesting as I can't see anyway to dim my guages without affecting the operation, as the power to the guage and power to the LEDs is the same connection.

 

Without opening up the guages and modifying them that is

 

But if it saves me the effort of trying to get the guages apart without trashing them, then thats a bonus

And Rich you're basically making up something like this ?

 

http://www.ebay.co.uk/itm/Universal-Daytime-Runing-Lights-Lamp-DRL-Module-Relais-12V-LED-R87-Car-Auto-/320980050640?pt=UK_Other_Clothing_Protection&var=&hash=item4abbe6e2d0

 

 

Yep my circuit does exactly what that DRL controller does

That would be interesting as I can't see anyway to dim my guages without affecting the operation, as the power to the guage and power to the LEDs is the same connection.

 

Without opening up the guages and modifying them that is

 

But if it saves me the effort of trying to get the guages apart without trashing them, then thats a bonus

 

I have a seperate pin on my gauges for the lighting mate...as you say with a combined live its a bit more complex