This PLL with operational amplifiers was found in 1969 documentation. The configuration can be adapted to use modern components. The circuit has a gain of 15 V / V and can operate with 10 kHz signals.
This triac circuit was taken from an article in the July 1970 Radio Electronics magazine. Note the...
When this circuit picks up a louder sound it produces a pulse that briefly charges the 10 uF...
This 10 A solid state relay was found in a 1980s documentation. It can work as a shield and...