I have a Teensy 3.2 based cylinder stroke comparator which signals a relay when the programmed distance is moved by a hydraulic cylinder rod.
Being an industrial application, it is powered by the 24V dc power rail in a panel and then i am using a Dc-DC converter to step down to 5V to power the MCU PCB. All well .
Till the Variable Frequency Drive in the same panel is switched on - after that the stroke display starts rolling over by +/- 20 counts.
Tried to power the MCU PCB with a 5V power bank and all is well again.
So the culprit is the 24 V dc power rail in the panel which kind off couples noise from the VFD.
I am looking to put a proper EMI / EMC filter on the 24V power supply as it enters the MCU PCB. I have seen some like these on some DC powered instruments ( some kind of ferrite torroids ? )
MarkT:
Is the teensy and its sensors fulled screened and shielded from EMI? What sensors are you using?
Only one 5K multi turn potentiometer connected with a 3 Core 0.25 Sq mm shielded cable with the shield connected to GND at the MCU end and left unconnected at the potentiometer end. The cable length is about 3 meters.
Apart from this the MCU pcb has no other shielded enclosure if that's what you mean.
