Hereís a mod I did to put RGB functionality into a light without sacrificing the white beam. Iíve done a lot with the multi-die color emitters (MCE and XML), but using the white emitters in those usually result in a poor beam (especially with reflectors).
For this one, I took one of my favorite cheap lights, the Romisen RC-A4, and set red, green, and blue emitters into the reflector. The primary emitter was upgraded to XML, and the driver electronics were highly customized to operate all the LEDs.
For the driver, I removed the 8-pin microcontroller from the stock boost driver, and replaced it with a PIC12F617 with custom software. The PIC takes over the job of the original chip by sending a PWM signal into the boost driver to control the brightness of the white LED, and it uses three other pins to control the color LEDs. Each color LED uses a single 7135 350mA current regulator, and gets its positive supply from the output of the boost driver. This allows me to operate each LED independently and simultaneously, so I can do PWM for each color channel and mix colors.
The software is an adaptation of the code I originally wrote for my RGBWUV flashlights that I put into the Romisen RC-C6 aspheric light: http://tterev3.blogspot.com/2012/10/...ashlights.html. It has a number of improvements over that light, including more strobe options and the ability to customize the low level. I know many here on CPF hate having too many modes, but I build these multicolor lights because theyíre fun to play with and show off the LEDs, so I have a strict policy of adding more modes every time I revise the code and never removing any. Iím up to 28 modes on the most recent revisionÖ
I used a small manual mill to add the spots for the RGB emitters, milling down to leave about a 1/16th wall on the inside of the reflector, and then drilled a hole to fit the domes of the LEDs. I drilled wire routing holes down the base of the reflector, and then installed the LEDs by filling in behind them with Arctic Silver. This is possible because the AS isnít electrically conductive, and the end result is that the reflector can still slide right into the host and the LEDs have a good thermal path.
The stock driver only needs 1 output from the microcontroller to send PWM to the boost driver, so I just ran wires from 3 other pins. The 7135s are sealed in shrink tube to insulate them. Thereís plenty of room in the driver cavity for all the extra wiring. There was a tricky issue with not being able to screw the base into the reflector with the added wiring, so I drilled axial holes into the base and ran the wires around the outside. It still fits into the host because the base is narrower than the reflector.
Hereís a demo of the modes and user interface. Here's a link to the source code in case anyone is interested in developing their own drivers: http://code.google.com/p/everetts-bl...0RGBW%20v1.ASM