Using 4 operational amplifiers this circuit generates 4 different tones. The circuit is from an American documentation from the 90's. Operational amplifiers are tTL084.
This circuit was found in the April 1984 issue of Radio Electronics magazine. The integrated...
The presented circuit was found in the National Semiconductor's Linear Applications Handbook from...
This circuit is basically the same as the previous configuration (CB15616E) with a power stage with...