XORBell is a Eurorack module with two logic circuits and five internal drone oscillators.
Green knobs are primary tune for the oscillators underlying each side’s output circuit. The white knobs are attenuverters for the cv input to those oscs.
With no inputs, you have two levels of drone complexity, and each circuit can be used separately as a logical XOR circuit for interesting rhythm operations.
Five trimmers adjust the v/o scaling of each osc, but they aren’t meant to be perfectly in tune, keeping them offset allows for the dissonant metallic drone we’re after. Works great underlying percussion or accompanying a filter.
![](http://karltron.com/wp-content/uploads/2024/08/xb_front-372x1024.jpg)
Item | Price | Note | |
PCB/Panel | three PCB | $30 | White panels |
Full Kit | Sack of parts | $100 | Kit incl PCB |
Assembled | Working Module | $150 | Tested! |
Power draw – measures 31mA on +12 and 28mA on -12V.
Assembly BOM shows the 4070 and 40106 internals.
![](http://karltron.com/wp-content/uploads/2024/08/xb_back-457x1024.jpg)
![](http://karltron.com/wp-content/uploads/2024/08/xb_left-464x1024.jpg)
These parts are 0805 size , which are considered doable by human hands, but you’ll need a fine soldering iron and thin solder, some tweezers and a clean workspace so you dont lose any tiny parts. Parts are spaced and labeled so I hope it’s easy to build, just ask if you run into any confusion.
The five test points on the back are mislabeled on v 1.1 so tp1 doesn’t go to osc1, but that doesn’t hurt anything.