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.
Although it is a common configuration today, these circuits were taken from an old publication. The...
This circuit can be used with any auio amplifier, converting it into a AM receiver. Antenna is a...
This non-inverter circuit was found in a Radio Electronics. It shows the basic configuration of a...