This circuit for musical instruments was found in a 90’s Elektor. The circuit still applies, as the components used can still be obtained with some ease.
Other operational amplifiers series, such as the MC34072, MC34074, MC35071, MC35072, MC35074 d...
The transistors in this circuit from an English publication in 1980 may be the BC548. Operational...
The circuit is from 1968, but we can use a modern one like the 741. The symmetrical power supply...