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 generates a PWM control signal using TTL logic. We found this configuration in a 1976...
This circuit, found in EDN documentation from the 90's, implements a clamp without signal...
September 2017 - Arduino Lucky Shield shields containing a 5 V OMRON-g6RL relay, a Everylight...