This circuit was found in a Popular Electronics documentation from the 90s. It is possible to switch the frequency of an oscillator by voltage. The circuit can act as a shield.
Using an integrated circuit from the time, this circuit was found in Radio Electronics from the...
This shield circuit is from old documentation. The operational amplifier used is not common today...
This circuit powers a small 5 W lamp that goes out when power is lost. The circuit can use the...