This simple optical alarm circuit was found in the 1991 Electronics Experimenter Handbook. The circuit uses a lamp as the emitter but can use LEDs.
This circuit makes use of a transconductance operational amplifier. It generates signals with TTL...
This circuit uses na Unijunction Transistor (UJT) to produce a modulation tone for several...
This circuit was found in General Electric documentation from the 1980s. The circuit uses couplers...