WAYNE CHIRNSIDE wrote in a message to MIKE ROSS:

 MR> The galena used to be substituted in the early 20's by some 
 MR> specific brand of safety razor blade. Apparently the razor blade 
 MR> metal manufacturing underwent a "bluing" process that made it an 
 MR> ideal rectifier. Probably some type of oxide, in other words a 
 MR> metal/oxide rectifier. Those had a pretty low junction voltage 
 MR> just as germanium. The easiest is still to simply use a 1N60A or 
 MR> 1N34 but then they didn't have those in the 20's.

 WC> Popular Electronics ran a circuit of a modified Xtal reciever 
 WC> where the signal diode was biased into it's active region by a 
 WC> common carbon - zinc battery with the bias voltage adjustable to 
 WC> just above the barrier voltage with a center tapped 1.5 Meg ohm 
 WC> potentiometer IIRC. Never built the critter but it looked good on 
 WC> paper.

I ran across something pretty similar on a web site,  only they used a
schottky diode,  and a watch battery.  No real current drain,  since it was
biased just short of conducting,  but it did reportedly have a heck of a
lot of sensitivity.

I forget what he did for headphones,  not being able to get those other ones.

Maybe a piezo "buzzer" would work?  That's basically the same
idea,  isn't it? And they're scroungable here and there...

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