Found in an Electronics Now from the 90s this mixer has several inputs. The integrated circuit can still be found easy and the power supply need not be symmetrical.
This digital instrument input circuit was found in the September 1989 issue of Radio Electronics...
This wireless infrared remote sound transmitter is from an article published in the August 1988...
This low power TTL circuit (Low Power Schottky) can generate rectangular signals on a 10 MHz...