This circuit is from an article that teaches how to assemble it in the magazine Electronics Now from July 1993. It uses a liquid crystal display module from the time with 3 and a half digits.
This circuit, suggested by National Semiconductor, is a tone control (bass and treble) with high...
This circuit from a Japanese publication in 1968 uses germanium transistors from the time like the...
This circuit is from a publication by Newton C. Braga in the United States. The transistor can be...