Variable colour LED clocks - Possible?

[Daz155HGT]

I was planning to change the colour of the dials, but after getting some insparation from a car on top gear, i am going to attempt to fit the same thing in my Bravo...

I know someone has managed to get rid of the green (by sanding?), i wan't to do the same, but fit 3 LED's in place of the bulbs.

Then i have the task of getting the colours to change. It would be "easier" to fit 3 coloured LED's and use switches to have a choice of Red/Blue/Green or a combination (ie Red & Blue on at the same time). But my idea is to fit 3 variable potentiometers and control each colour gradually.

This is where i need your help.

Has anyone used variable pots to control LED's, for a dimming effect?

Or any suggestions would also be helpful...

Cheers

Daz

 

[Tom]

Just using pots won't give you a good dimming effect, you'd get on.. a little bit dimmer.. off.

LEDs need to be pulse controlled. Which isn't that hard.

You could either do it with a microcontroller, say a PIC or use some 555 timer chips and 3 pots to control the 555s.

 

[Daz155HGT]

"Just using pots won't give you a good dimming effect, you'd get on.. a little bit dimmer.. off"

I just found that out , i have to turn the pot to around 90% before you see anything on the LED, then its very sensitive upto 100%, too sensitive to control.

I have found a good tri-colour LED (4 legs), which will be better than 3 seperate ones, as i won't get red/green/blue area's.

As for the microcontrollers, got any links or sources...?

Daz

 

[Tom]

Drop me a mail with exactly what you want to do, I may have a solution.

 

[Daz155HGT]

Mail sent.

Daz

 

[Craig]

maplin do the 555's
there are or were lots of projects on the net for the 555 and 556 chips as they can be used for lots of different things.
motor speed control was what i used the 556 for at the time, its two 555's in one package.

 

[Anonymous]

Don't mess about, use a PIC (www.microchip.com)
You are probably best using the PIC to drive a transistor, and use that to drive the LED, as the PIC can only drive 25mA.(You will need three transistors to drive the 3 leds that are necessary for the complete spectrum) I've knocked up little light circuits that slowly change through all colours of the spectrum, or you can program your own patterns. A more advanced circuit could be linked into the rev counter so that the colours change with rpm.

But if you don't have the time/skills to program a PIC then Maplin are selling colour change balls for £9.99 that go through the colours of the spectrum and you might be able to extract the circuit and bodge that in. You'll probably have to use a voltage regulator to reduce the voltage from 12V but these are easy enough to rig up. You will need a 7805 (Maplin) and a bit of Veroboard and a soldering iron. The datasheet for the 7805 will be available on the web from the manufacturer who makes it (loads do, but go to the right manufacturer to make sure the pin-out is the same), and it will show you the circuit needed for a 12 to 5V regulator.

Nick

 

[Allan Wall]

re

when i did electronics at school we did loads of 555 chip projects,

that was 6 years ago and i cant remember anythgin now though !Lol