The A440 Kit produces a reference sine wave at 440 Hz, or middle A. The frequency is crystal controlled and the sine wave is very clean. This stand-alone board can be mounted anywhere and be wired to any kind of jack or other circuit.
The kit uses a standard 10 pin Eurorack power connector, or power can be wired directly to the board.
![](https://i0.wp.com/circuitabbey.com/wp-content/uploads/2023/07/A-440-board.png?fit=250%2C138&ssl=1)