EMI issues and optimization - TomBric/stratux-radar-display GitHub Wiki

On several devices I experienced EMI (electo magnetic interference) issues. That means the stratux devices disturbed aviation radio frequencies. This radio noise occured even in the case where I used a grounded aluminum case. The noise was on the GND lines and was "transported" by the GPS mouse outside the case. The following measures helped to reduce the EMI disturbance to a minimum:

• use a ferrit core (material 43, NiZn). Place it immediately after aircraft power and GND enter the device. Twist both cables twice around the ferrit core.
• use a second ferrit core (also material 43) for the 5V and GND cable immediately after the step down converter (twist twice)
• twist all Power/GND cables inside the device to reduce disturbance
• twist all power/GND cables to the device

My experience is that some XL4015 based step down converters create a lot of EMI noise, others did not. My suggestion is to use

• D42V55F5 - step-down converter - 5V 6A - Pololu 5571

instead. This converter is LM5149 based and produces less EMI noise.