GrahamH

GrahamH club

Posted: 07 Jan 2013


Taken: 07 Jan 2013

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1/160 f/8.0 5.0 mm ISO 200

Canon PowerShot A1200

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band
diode
resistor
homebrew
earphone
transistor
earpiece
inductor
capicitor
portable
broadcast
electronics
radio
australia
slide
kodak
box
home made
am
walkman
tagstrip


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Earphone radio 1968 007

Earphone radio 1968 007
A pocket personal portable AM (no FM at that time) radio which I built in a 36 exp slide box at the start of the 68/69 Christmas school holidays. It was originally built breadboard style with a valve-style tuning capacitor. The circuit has three transistors. The signal path flows from the ferrite rod to the first transistor for RF amplification with regeneration. A diode demodulates the signal which is sent back to the first transistor reflexed as the first AF stage. Two more transistors cascaded give more AF gain. A high impedance crystal earpiece couples the audio to the Listener. Performance was adequate for primary coverage areas. See Notes on 005.

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