The frequency of each note depends on R2, which must be replaced by a keyboard. The circuit is from Radio Electronics from April 1980. The power supply is 9 V for the amplifier used.
This circuit with an industrial standard 4-20 mA interface uses a KPZ20G pressure sensor but can...
We found this circuit in the March 1992 issue of Radio Electronics magazine. The circuit has a...
Found in a 1964 Electronic Design, this circuit suppresses arcs that occur in contacts when a...