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    Building, troubleshooting and testing of these amplifiers should only be
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my latest 300B's
with ECC81 Telefunken pre stage current sources in anode and cathode
extremely quiet. almost 9W before clipping
 

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my latest 300B's
with ECC81 Telefunken pre stage current sources in anode and cathode
extremely quiet. almost 9W before clipping

My search may finally have ended - I've been trying to find the name/type of a numerical display unit I had once as a kid. I liked to take things to pieces and this one was lost. It was a stack of perspex sheets with indents which light up when you put a small incandescent bulb to the edge. So the perspex sheets were formed into waveguides so a bunch of bulbs at the back of the unit would be used to select which number would be illuminated. Well it just looks like you have a pair of these on your shelf - I can't be sure but I would love to know what they are called, who made them because I forgot.
 

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My search may finally have ended - I've been trying to find the name/type of a numerical display unit I had once as a kid. I liked to take things to pieces and this one was lost. It was a stack of perspex sheets with indents which light up when you put a small incandescent bulb to the edge. So the perspex sheets were formed into waveguides so a bunch of bulbs at the back of the unit would be used to select which number would be illuminated. Well it just looks like you have a pair of these on your shelf - I can't be sure but I would love to know what they are called, who made them because I forgot.

I'll have a look on thursday, not at home now. they look very much like the one in hearinspace post. but they are modular. I found them in a military junk shop. they work.
 
Yeah, that's the right technology indeed. The one I had was a single digit, it was modular. The plastic waveguides were bent though 90 degrees so that their edges were available at the back of the module for all the little light bulbs - I think. Anyhow, thanks for the trip down memory lane, must have been 45 years ago !
 
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