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 General Electric circuit was published in 1970. The LED is infrared and the voltage according...
This circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an...
The transistor can be a modern equivalent and the transformer is the type of output found on an...