If I had AC, I'd probably just run it through a little transformer, rectify it and regulate the current, but I have half wave rectified, so a standard transformer is out. I'm planning in a couple of pretty big smoothing caps, which will bring the RMS up, but I'll still have 167 or 68 peak. I think if I can get the min voltage up to about 20 or 24 volts, flicker will be imperceptible. The LEDs come on at 30 or 31 volts and Cree calls "typical" 100 % at 35 volts, 120mA. 175mA is absolute max current and 40V is max voltage - according to Cree. So, if I get the min volts to 34 or 35, there should be zero flicker. AND, this is the Low circuit, so I want probably 150 or 200 lumens rather than 400 - 450. There ought to be an easy way to get from 120V VAC -> half wave rectified -> 40 or 48 smooth volts DC. This has always been the challenge. The high circuit from the switch is 120 VAC, the Low circuit - from the switch is 120 VAC,,, half wave rectified. I can't change the switch, it is part of the key pad assembly. I have considered using the OFF-HIGH-LOW switch for nothing more than a control signal to a different power supply, which would drive the new lamp. Too much trouble. I'd have to take the stinking microwave down from where it's hanging. I'm gonna screw in my nifty intermediate base (E17 - I think) converter, plug into that, punch a "button" on the nuker panel, and "Let there be light",,, in the appropriate amounts.
I'm gonna say this again. I've already learned way more than I intended to when I started this project,,, and it has been FUN!