Using a 709 integrated circuit this circuit was found in the June 1972 issue of Radio Electronics magazine. More modern operational equivalents can be used. The power supply is symmetrical.
Using a 741 op-amp this circuit high-pass to 10 kHz was found in the February 1995 issue of...
Found in 1965 General Electric documentation this circuit applies to a LASCR used as an optical...
Using transistors and lamps, this simple circuit was found in Popular Electronics. The circuit can...