Test circuit with bridge (CB22530E)

This bridge-biased transistor test circuit measures gain in the range 0 to 300. Circuit is from Radio Electronics June 1952.

Telephone Disc Simulator (CB12072E)
This circuit mimics the dialing of an old telephone. The reproduction is made in a loudspeaker and the power...
2 kHz Low Pass Filter (CB13594E)
This filter is from a 1977 manual. The integrated circuit is 741. The frequency is given by f = 1...
Passage Alarm (CB26162E)
This simple optical alarm circuit was found in the 1991 Electronics Experimenter Handbook. The...