This interesting transistor circuit has several effects and an included amplifier. The circuit is monophonic and powered by standard batteries. The number of keys can be changed.
This metronome configuration with the 555, quite common was found in a 90s Hands On Electronics. The...
We found this circuit in a 1964 Electronic Design. Transistors can be modern general-purpose...
As monostable we have a proximity switch that can be used as a shield, since the capacitance of...