Matthew Smith wrote: > Quoth Folderol at 2008-11-15 21:49... >> Fascinating bit of kit. I'd be inclined to try to keep it as complete >> and original as possible. I doubt you'd have a problem with the >> capacitor. I know someone with a WW2 communications set that still has >> almost all it's 'dry' caps, and only half the electrolytics have been >> changed. > > I have to confess, I do feel an urge to restore it. > > I will certainly do preliminary tests (once I've got the thing spinning) > with and LED and a phototransistor, just to see what it sounds like, but > getting a proper setup with the lamp and selenium cell seems like the > Right Thing To Do. I doubt it'll be a selenium cell LDR, that wouldn't really be fast enough for 3kHz. What you might find is that it's an early photodiode, consisting of a thin metal rod for the anode and a C-shaped cathode. There are special coatings on them, and the current flowing through changes with the amount of light falling on the cathode. They need biased to about 150V to work properly, but you should see *some* sort of output with as little as 9V. Gordon _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
