10 Second Timer (CB21421E)

This circuit from a 1966 General Electric manual makes use of an SCS. The time is given by the emitter capacitors of the unijunction transistor.

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Sound operated switch (CB9214E)
This circuit was found in a Hands On Electronics from the 90s. The microphone is a small 75-ohm...
FET Stage with Gate Offset Adjustment (CB26251E)
This JFET amplifier stage was found in the Encyclopedia of Electronic Circuits Volume 5 from 1995....
Optimized Operational (CB15106E)
To obtain more output power from an operational amplifier, we can use a transistor, as shown in...