DC DC Converter (CB21822E)

We found this circuit in Mullard's 1960s transistor manual. No information about transformers is given. Transistors are germanium types of the time.

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Wien Bridge Oscillator (CB9040E)
This circuit has a frequency range of 30 Hz to 100 kHz with an output signal of 1 Vrms. We found...
AC Phototransistor (CIR812E)
This circuit is suggested by the Optoelectronics Sourcebook by Texas Instruments when AC signals...
Traffic Light (CB21013E)
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