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.
This circuit can be used with common transistors, from general purpose to medium power. The...
This configuration can be found in almost all LM117 manufacturer's manuals. This circuit,...
This circuit was published in Popular Electronics from the 90's. The components are common, as...