This two-transistor circuit was found in the September 1971 issue of Radio Electronics magazine. The sensor is an NTC and sensitivity adjustment is via R1.
This circuit, which in our times would be called a shield, can also be used with other loads. The...
This circuit was found in a 90s Popular Electronics. It uses an LS3404 melody chip that has...
This circuit is ideal for recovering vinyl media with a linear response from the RIAA curve of the...