Using the LM3909 this circuit was found in the January 1992 issue of Radio Electronics magazine. Resistor R1 should be chosen according to the table given next to the diagram.
S1 changes the selection of the input signals in the circuit shown here. Other type of circuits,...
Found in documentation two years 80, this toy instrument uses an integrated circuit little...
With this configuration, greater power can be obtained from an operational amplifier, thanks to...