This circuit was obtained from a 1967 General Electric manual. The circuit uses components of the time, but equivalents can be used, for example, a BC547 for the transistor and a TIC106 for the SCR.
This circuit was found in a Popular Electronics of the 90s. The operational amplifier admits...
This is the typical circuit of a local oscillator for a superheterodyne FM receiver. The circuit...
Found in a 1968 Motorola publication, this circuit generates a high-powered audio tone when...