Photos, videos and docs of GrahamH, with the keywords: "earphone"

Earphone radio 1968 009

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:29:36 +0000

GrahamH has posted:

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.

Earphone radio 1968 007

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:27:38 +0000

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Earphone radio 1968 008

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:28:38 +0000

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Earphone radio 1968

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:30:49 +0000

GrahamH has posted:

A pocket personal portable AM (no FM at that time) radio which I built in a 36 exp Kodak 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.

An oldie added to kick off the Macgyverering group. Using a 36 exp Kodak slide box as a radio case.

Earphone radio 1968 006

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:26:22 +0000

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Earphone radio 1968 005

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:25:06 +0000

GrahamH has posted:

A pocket personal portable AM (no FM at that time) radio which I built in a Kodak 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 good for primary coverage areas.

Earphone radio 1968 003

nobody@ipernity.com (GrahamH) — Mon, 07 Jan 2013 08:23:46 +0000

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