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.
This good quality stereo amplifier was found in a Japanese publication from the 1960s. The circuit...
This circuit allows you to use the parallel PC interface to control LEDs. The circuit was found in...
This circuit, with printed circuit board, is from an article in Radio Electronics magazine from...