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 circuit has its frequency controlled by a 1MHz crystal. The circuit can be powered by...
This circuit is from a publication from the 60s. The transistors used are of the first commercial types,...
This filter, found in an old manual, has characteristics of reduced overvoltage given by the graph...