Variable colour dash lights

[Apothus]

Im looking in the next couple of weeks to be making up a circuit where i can change the colour of my dash lights or have them cycle through the colour ranges using leds.

I originally tried the straight blue led replacements, Bad Idea! For some crazy reason some decided to turn into strobe light (cant even began to understand why! apart from faulty manufacture) before dying so currantly all i can see is the spedo at night.

I am planing on replacing the globes with RGB leds (Red Green Blue, the primary colours of light) then using a microcontroller (AVR) to controll a PWM signal to each of the leds, this will turn them on and off V.quickly and adjust how bright we percive each colour to be. A variable resistor will controll the PWM signal and ultimatly adjust the brightness of the leds so you can mix any colour you could imagine.

Hopefully this will result in a nice even dash light and rgb led controller. I am also plaing on making the circuit multipurpose so you can controll up to 2amps of leds/globes/lepricons/etc via pwm.

The reason im posint all this here? First i want to see if anyone has made something like this already that i cant find. I also wanted to see how many others are interested in this as to wheather i should make a complete DIY or even make up kits for those who dont have AVR programmers to make their own.

So what do you all think?

[rock_it]

I am very interested !!!!

I had the same problem as you ... I got the LED lights, and they worked great for about a week or too ... They were meant to be hyper white ( to match my Auto Gauges) but they still turned out to be kind of blue/grey ....

I actually wanted to try and get someone to make something that worked like the smoked gauges.... So, if you are making one with a dimming switch, you could use really bright LED's, tint the notmal perspex cover, and be able to see the lights day/night ... Which would be what I want ....

Like this ...

[Apothus]

Yeah that should defiantly be possible, the leds im planning on using are rather bright. im also going to be looking at adding a few extras to give a much more even dispersion of light.

I am also planing on including 5 other pins on the board as colour overrides. So when you apply 12v to either pin it overrides your preset colour to a different one. Essentially this will allow you to change your entire dash into one giant shift light and turn red at 8000rpm! or if someone leaves a door open it will remain a cautionary yellow.

Also if anyone knows what type of signal is sent from the ecu to the tacho that would be great, otherwise an external shift light would need to be cannibalised to make it work.

[rock_it]

I like the way you think ...

Hook me up ....

[RK1-WhiteKnight]

Sound similar to the 2" type-r gauges I've got, they cycle through about 7 different colours. I could make a video if your interested

[Apothus]

I know the style that you mean. and they work in a similar fashion. I personally am not a fan of fast colour changing leds (i prefer 5min between colours although this too will be variable).

Do the ones you talk about fade slowly or 'click' through the colours?

[Apothus]

After talking to a few of my mates about this and seeing confused glazes go across their face or their msn screens i thought i would go into a little more detail and break things down a little more.

1. Why not just use capacitors and resistors like regular globes?
A good question, leds are one of these awesome things called semiconductors! semiconductors behave differently at different voltage levels so when you connect an led to a variable resistor to fade it you are adjusting the voltage to the led. When you adjust that voltage strange things start to happen. first it will appear to dim and change as you move it but as you get towards operating voltage the intensity will jump and it just looks plain nasty!

2. so WTF is this pwm thingy?
Pulse Width Modulation is used in thousands of places! most commonly in applications such as remote controll cars to control motor speed and servo positions! PWM is a digital signal, it is either on or off, what we are changin is the difference between the on time and the off time, hence the "Pulse Width"
low brightness led voltage signal (ignore full stops in diagrams, just so as it formats properly, the lines indicate voltage)
..........._..........._..........._..........3v
_____| |_____| |_____| |__ 0v etc etc
when we want the led brighter we have the pulse length ON longer
.......___.........___........___ 3V
___|......|___|......|___|......|_____ 0V etc etc
full brightness has us adjust the ON time even more
..._____...._____...._____ 3V
_|..........|_|.........|_|.........|___ Ov etc etc

of course each pulse happens very quickly, less than 0.0001 seconds between pulse starts

3. wont this give me that same disco effect?
thankful no! you may have heard of something called persistence of vision (POV) our eyes take a "photo" 25 times a second then our brain process this into a moving image. TVs etc change the picture on their screens more than 26 times a second hence our brain sees moving pictures. The rediculously fast rate of the ON/OFF switching of the LEDS results in us seing a constant glow of light. SO the lnger the pulse of light the more that goes into our eye and the brighter we percieve it to be


any more questions just ask, as you can probably tell i ave a rather keen interest in this[/img]

[rock_it]

Hmm ... Some good info there ...

well, if you do get it all happening, and manage to make it look like the picture of my smoked gauges... I am in for sure ....

[Supplanter]

Sounds like a fun DIY project

Any chance of knocking up some PCBs or pre-programmed AVRs?

[Grue]

Something like this?

http://cgi.ebay.com/Rainbow-Colour-Chan ... 638Q2em122

I'd probably think that they were pretty cool for about 10mins. Then get fed up with them

[Apothus]

I am hoping if their is enough interest and if it all prototypes nicely to do just that. Order a batch of pcbs and components, ill probably get a new programer too, the one i have is 5 kinds of useless (damn you jaycar!).

The ebay lights are a little similar yet these ones will be able to do more than cycle. What i am wanting from it is to be able to select a colour and leave it set to that, a few days later i may want to change it so i just twist the dials. The reason i will have it cycle through colours is because on a programing scale it is very simple to add and a nice optional function. The part im excited about is the shift light option

[Jamie]

I am doing something very similar at the moment.

I am planning on putting RGB LEDs behind the instrument cluster on my FTO. The aim is to have the cluster start from green and change through yellow, orange and finally red. Effectively changing the dash into a giant shift light.

I was going to use PWM aswell. I am hoping the speedo has a digital input and that somehow I can use the changing frequency to change the colour of the LEDs.

Does anyone know if the 1997 FTO has a digital input for the speedo?

[Apothus]

Not sure. it must be a digital input of some kind as the cluster just has electrical connections. A voltage range would make sense as they are gauges although it may be variable pulses. If anyone has a scope they could tell

PHASE 1 COMPLETE-----

I have installed the leds in the dash, they look great but a few points.

1. I do not think they are bright enough to use as stealth gauges.

2. they draw a considerable ammount of currant, they make 5W resistors rather toasty.

LED INSTALLATION
Relatively easy to mount, used the standard connectors, drilled them out with a 6mm drill bit. Insert leds and set with hot glue.

Then i considered soldering wires to each but i decided in the long run it was easier to use 10pin connectors
http://www.jaycar.com.au/productView.as ... BCATID=278
then ran ribbon cable to connect them all up.
the beauty of this is that everything still fits together even after adding and extra 10-15mm of depth to the cluster.

then i just made up a little switching box so in the mean time i can just select the colour i want.

Ill be uploading photos of the final installation soon.

[rock_it]

Cool ... Can't wait for the pics....