The circuit presented is from the 1993 Linear Technology Applications. The components used were common at the time.
The transistors in this circuit are 2N2222 and general-purpose diodes 1N4148. The circuit is from...
We found this circuit in a 2002 documentation. The frequency of each note is determined by the...
We found this circuit in an Electronics Now from the 1990s. The circuit crashes when light strikes the...