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.
The transistor of this circuit found in an old American documentation can be the BC548 for T1 and...
This circuit, which appears at other points on this site, can be designed with both 4011 and 4001...
Intervals of more than 39 hours can be obtained with this programmed circuit that we found in a...