Here is my homemade Switch Box.
It is an A/B box with 2 inputs, and it can be used as an Effect Loop Box with the flip of a switch.
The schematic is shown both for a basic Switch Box, and for a more elaborate one.
In the basic Switch Box, you have to use the Input 1 if you connect only one guitar to the box, because only that input switches the battery on, and only input 2 is muted with no guitar connected.
In the second one that I built, I used better jacks, so that I could switch the battery on with any two of the inputs, and both inputs are muted with no guitar connected.
© 2003 Gilles Caron