Pocket Tube Radio (T1621E)

This sensitive 4-tube, battery-powered receiver was found in a 1949 Radio Electronics. The circuitry was wired in crystal earphones.

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Servo amplifier (CB23814E)
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Headphone adapter as equalizer (CB23842E)
In the figure we have adapter circuits for using stereo headphones in an amplifier without a...
Tremulo circuit (CB10115E)
This circuit was found in a National Semiconductor manual from the 1970s, appearing in articles and on...