Aprox 1.07 vdc no load / open circuit (my RS $8.95 mm)(remember: B3). A 2K pot gives me 195 mv and an Off condition ... turn, turn, turn... 55 mv (880 ohm) = On. Unturn, unturn... 125 mv(1800 ohm) = Off. My CdS cell shows 25k dark and 450 ohms with the LED on it. Hmmm, charting that says I should be good. However any advice gladly taken.