Recently there have constantly been bees (or bumblebees?) around two of the screw holes in our plastic front door.
They buzz around a bit but don’t actually crawl inside.
It looks like cement has been put into the holes—a gray, hard substance that wasn’t there when we bought it.
Does anyone know what these bees are up to?
Setup; an Arduino controls a PCA9685 that controls a digital servo that needs to operate the throttle wire of a motor dyno test bench. Everything works as expected, until the frequency inverter driving the room exhaust AC motor is switched on.
The servo has its own 20A 5V power supply, which has a shared ground with the PCA9685 sending a 333Hz servo signal. The distance between control room (where the signal is generated) and servo is ~5 meters. Currently the signal wire together with a ground wire is routed to the servo.
This signal gets very messy, see video of scope...
Servo, understandably goes vibrating and does react properly.
What are the best options to filter this noise out?
Shielded COAX cable with the shielding tied to ground?
Ditch the idea and let a microcontroller closer to the servo control it, getting the right position through CAN / RS485?
Some RC filter?
Ferrite beads everywhere? 😅
???
Thanks in advance!