I need to gradually change the hue of a 3 colour LED depending on it's position or angle...

The LEDs will be mounted on top of a rod which may be vertical or tilted. I want it to be one colour when vertical and gradually change as the rod tilts. The height of the LED will decrease, as the angle of tilt increases, from around 2 metres/6 feet to 0.5 metres/2.5 feet. It needs to be a cheap solution as I have to make many of them. I'm guessing that a tilt sensor might be the best way to go but they seem to be simple on/off devices in the price range I'm checking. Is there a better approach?

Thanks.

Like (0) Log In or Register to reply

MikeWeed
51 posts since
Oct 21, 2011

Currently Being Moderated

Jan 10, 2013 9:27 AM (in response to BongoPedro)
I need to gradually change the hue of a 3 colour LED depending on it's position or angle...

Consider an accelerometer. Some are very inexpensive, but unfortunately the cheapest only come in very small packages that are not feasible for manual assembly. The best I could find for manual assembly is the MXR6500MP ($4.91US from Digikey). This is a 2-axis accelerometer analog output with adequate sensitivity (with an op amp, such as LMC6482). With any accelerometer you will need a microprocessor. I favor Microchip's PIC16F886 ($2US in quantity). The '886 has an A/D converter that can convert the accelerometer signal to digital, and plenty of processing ability to make the LED drive signals. To dim the LEDs, you can use a pulse width modulation (PWM) method. The
'886 has 2 PWM modules, and you can synthesize the third from the timers in the '886. The '886 outputs have a 25ma sink/source capability, so can drive the LEDs directly. This could be a fun project!

Report Abuse

Like (1) Log In or Register to reply
MetMan
86 posts since
Oct 24, 2011

Currently Being Moderated

Jan 11, 2013 11:15 AM (in response to BongoPedro)
I need to gradually change the hue of a 3 colour LED depending on it's position or angle...

This does sound like an interesting project!

Mike's suggestion of a multi-axis accelerometer is a good one. You could also use a multi-axis magnetometer (compass), or if your rod is rotating on a shaft or axle you could detect the shaft rotation by coupling it to a simple potentiometer or a shaft encoder. Have fun!

Report Abuse

Like (0) Log In or Register to reply