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.
We found this oscillator in a 1978 amateur radio documentation. The circuit supports other...
Small time intervals up o some minutes can be achieved with this circuit. Only incandescent lamps...
In the figure we show yet another CMOS component based voltage controlled oscillator circuit. The...