This circuit was found in a 1924 Gernsback publication. The variable capacitors are dual. Listening is through a high-impedance phone.
One 40108 Schmitt inverter or one 4093 gate can be used as a half monostable to be triggered by...
This signal generator found in Japanese documentation of 1973 uses an unusual integrated circuit...
This is the basic configuration of an operational amplifier as a current regulator. We found it in...