4-tube reflex (T1662E)

This circuit that uses a loop antenna was found in a 1924 publication. The circuit has several supply voltages and sets of audio and RF coils.

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Unijunction transistor sequential timer (CB21400E)
This circuit was found in Motorola documentation from 1968. Transistors can be modern equivalents, just...
Protected Residential Alarm (CB18674E)
This alarm is powered by the power network, but it has a source that charges a battery that goes...
Wireless Sound Transmitter (CB25156E)
This wireless infrared remote sound transmitter is from an article published in the August 1988...