This differential amplifier, found in a 1964 Electronic Design, has a gain of 30. The setting can be applied to modern equivalent transistors.
Small time intervals up o some minutes can be achieved with this circuit. Only incandescent lamps...
Frequencies from 1 to 10 MHz can be obtained with a small adjustment of the variable in a narrow...
Found in an Electronics Now from the 90s this mixer has several inputs. The integrated circuit can...