The gauges all work! This was no small task. Each gauge requires a digital input signal. The frequency of the signal determines the angle of the needle. I programmed a microcontroller to send the appropriate frequency to each of the four gauges. The microcontroller also listens for new data from the speed, rpm, volt and amp sensors. The communication between all sensors uses the Controller Area Network Bus (CAN Bus) protocol.
The plywood support bracket is only for our testing.