This variable filter that lets frequencies from 500 Hz to 1500 Hz pass through was found in a Popular Electronics from the 90's. The operational amplifiers are the 741.
Found in RCA documentation from the 90s, this circuit uses integrated components from the time. The...
This circuit was found in an American documentation from the 80's. The transistor is a...
Suitable for recovering tape recorded media from a common tape player mechanism, this circuit is...