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 1940 Radio has Photo-Electric Pick-up Cartridge
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 Return to top of page · Post #: 1 · Written at 6:40:55 PM on 3 November 2014.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 606

I picked this up at Habitat-for-Humanity charity store last week (they resell donated items)

Philco Radiogram
Philco Radiogram
Philco Radiogram
Philco Radiogram


Radio is 1940 Philco – uses unique light/photocell Pick-up cartridge
Stylus vibrates mirror that varies intensity of light to photo cell (photo headshell removed)
Light source miniature bulb connected across cathode resistor
(lights slowly,shines through Deco-style Catalin-plastic headshell as well as shining “spotlight” on record surface)
Sounds very mellow like Optical soundtrack film!
Inbuilt rotating SW antenna (photo)

Unique Push Pull output uses screen grid of top pentode in triode mode to obtain inverted drive for lower pentode!
(never seen that circuit before!)


 
 Return to top of page · Post #: 2 · Written at 8:10:16 PM on 3 November 2014.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 5511

Sounds like a fairly complicated way of doing things. There was probably more 'bandwidth' on film, as the optical systems for the projectors worked and sounded fairly good, even in mono.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 3 · Written at 12:11:31 AM on 4 November 2014.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 5263

Nice find!

I faintly recall hearing about a PE type PU many moons ago (maybe in an EA article), and it's great to now see one.


 
 Return to top of page · Post #: 4 · Written at 2:26:10 AM on 4 November 2014.
NewVista's avatar
 Location: MilwWI, US
 Member since 10 May 2013
 Member #: 1340
 Postcount: 606

This technology stopped by WW II but I think there was a Toshiba stereo photo-electric cartridge in the 1970s or late 1960s.


 
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