We found this circuit in the September 1971 Radio Electronics magazine. The SCR can be any of the 106 series and the buzzer can be replaced by a relay according to the supply voltage.
This filter has the components calculated for the frequency of 1 kHz but can be changed. The input...
This capacimeter was obtained in European documentation from the 1980s. The indicator instrument, a...
This circuit was found in the Optoelctronics Sourcebook from Texas Instruments. The circuit has a...