This is the circuit of a modified Heathkit kit. The circuit was found in a Radio Electronics from December 1965. The author of the circuit included improvements to the original circuit.
This heartbeat sensor circuit was found in the July 1992 issue of Radio Electronics magazine. The...
This amplifier circuit with a low power MOSFET was found in Popular Electronics from the 90s. The...
This circuit, which can be built with several CMOS gates, was found in the March 1996 issue of...