Selectable Single-Polarity Supplies PUBLIC

Two selectable-voltage power-supplies for op-amp circuits. One with +9V or +5V DC, and one with +12V or +9V or +6V DC.

Op-amp circuits in guitar preamps and stomp-boxes will produce more distortion when overdriven at lower rather than higher power-supply voltages. Here are two single-polarity power-supply circuits that permit selection of lower or higher supply voltages for any given op-amp circuit. One circuit gives the choice between +9V and +5V DC, while the other gives the choice between +12V or +9V or +6V DC. These supply circuits can be used to choose between different sounds from a guitar preamp or effects device circuit even while in use during liver performances. A lower supply voltage gives more distortion, though with lower output, while a higher supply voltage gives cleaner sound, though with louder output. [To get louder output with more distortion, you must switch between two or three different preamps or effects.]