One Touch Window Button

Hi,

My car has a one touch window button. Should it be lit with the headlights on? If so is the bulb replaceable?

Cheers,
Niek

Yes.
No, unfortunately Citroen only sell the complete switch. I did take one apart some time ago, the bulbs (tiny little thing) can be removed but I was unable to source any replacements.

I recall doing a similar excercise.

The bulbs, or atleast similar shape, size and rating ones, can be sourced from www maplin co uk.

i dont recall exactly which model no. i purchased but they are not the standard push fit type found in the dash. The type of bulbs required are with flying leads which you need to wrap around or solder to the connectors inside the switch.

it can be done but fiddly springs to memory. if i can dig out the details of the ones i purchased i will advise.

This post has been edited by Gav on September 09, 2005 09:07 am

you can get 12V LED's these days, use them - cool and longer lasting

Will be fiddly to do though

I'll give that a shot, thanks.
If I recall right though, a LED is a diode. Does this mean you it will only work the 'right' way around?

Yes.

Peter.N.

LED=Light emitting diode.

From my distant memory, most LEDs had one leg longer than the other to denote which way round they went. Sadly my memory fails me as to which way round was which

I'll apply the trusty trial and error method

Niek,

I like the idea of using an LED instead of an incandescent lamp. I've replaced a few of these in my time with ones bought from Maplin and other places of that ilk. I too have some dark buttons in need of new lamps. However, a word of warning. The lamps in the buttons see 12v across them in operation. If you put 12v across a diode you'll simply blow it. LED's work on very small currents. As such you must have a very small voltage across them. It is normal to have a resistor in series with every LED to lower the PD across the LED itself. As far as I can remember I think the value is approx 1000 OHMS.

I'll need to have a closer look to see if the resistor and LED will fit in the space originally occupied by the incandescent lamp. I think it will be problematic.

Does anyone know of LED's with the resistor built in for 12V operation? That would be very useful.

Cheers

noz

Hi All

Each colour of LED requires a different operating voltage, Red is the lowest voltage and either blue or white, I cant rember which, the highest. I was going to get some white LED's to try for the dash bulb holders as LED's have almost infinite life. I was going to use a pair of LED's in parallel then the resistance in series. This would mean that one or other of the LED's would light up irrespective of the supply polarity. The calcs for value of the resistor are fairly simple, in the Maplin catalogue I suspect. Will go out and see if I can get some minature white LED's and let you know how I get on.

Regards

XMexc

Hi XMexc,

The polarity of the voltage to the lamp stays constant. Its only the windor motor voltage which reverses. As such you'd only need to establish the correct polarity once and install one LED only. The reson I say that is that the space where the lamp is located inside the button is very tight and I'm not sure you'd be able to get two LED's and a resistor in the space.

From a space point of view I was thinking about one of those tiny little surface mount resistors. Has anyone ever tried this? You'd think there would be a market for LED's with the correct built in resistor for 12v operation.

Cheers

noz

Hi Noz

It was for the dash bulb holders I was thinking about the back to back LED's. I guessed that Citroen would not worry about polarity here particularly if it added the cost of a couple of extra through plated holes for the printed circuit board every time there was a need to change the bulb holder contact polarity. I must admit that I was looking to design and prove the idea then make up enough to change every one in the dash as taking the dash to bits every time a bulb blows is not my idea of fun.
I have looked at some small red LED's on a PIC tutorial board that was to hand. They are less than 3mm in dia and 5mm long, the dropper resistor is 2mm in dia and 6mm long. Assembled as a package this will definitely fit the dash bulb holder but I will have to find a non working switch to pull apart to see how much space is available.
I have just found a little components catalogue from one of our local electronic surplus stores. They are offering: "a clear LED 3mm ultra bright supplied with a resistor to work off 12v or use on its own off 2.5v. Very bright - hurts when you look at it". I will go and get some next week to try as 6 in series in a switch would not need a resistor at all.
They also have another item: "fiber optic cable. stranded, transmits light, whatever colour you put in you get out the other end - if you split the cable you get lots of light"
It might be possible to bring the optic strands out the back of the switch into a single bundle that was lit by one led. I will get some of this cable also.
Will let you know how I get on with these bits.

Regards

XMexc

This sounds fascinating - please keep us posted.

Derek

Hi All

Have been up in the roof looking for LED's and other bits. To explain I have a little work room in the roof space where I keep all the electronic and computer junk (another of my hobbies of much longer standing than XM's). Had to move all the XM leather seat covers and door cards that I have been working on but eventually found a few colured leds to play with. A standard yellow led and resistor running off a 9v battery did not produce enough light to light up one of the warning symbols on the central dash display until I switched off the room light. I recon a white high brightness led running off 12v will work OK. I took a standard door window switch to bits to look at the bulb. It is mounted on the underside of a small piece of green plastic by winding each of the wire leads around two side projections. The bulb shines through the green plastic to illuminate the white arrows on the switch top with a greenish colour. None of it looks too difficult to repair. There is space for leds etc in these switches. Surprisingly the switch and its light still worked after I had put it back together. When I find a spare one touch switch I will take that to bits to see what that is like inside. I will see if I can identify the bulbs take some photos and put together a help note.

Regards

XMexc