Noise impact on servo?

When switching on the fluorescent light in my shed workshop, a powered up servo (HS 311) briefly goes through some erratic movements - despite its 3 metre servo control wire being disconnected at the UNO end. Can I safely assume that, when it is connected and operating the sketch normally, such interference would have no adverse impact on the programmed behaviour?

The servo is powered from a regulated bench 5V supply, with 0.1uF near the servo. The UNO is supplied from either the same 5V, sometimes with the USB PC cable also connected. The pair of wires supplying the servo are about 2 metres away from the bench supply unit, which is about 50cm from the UNO.

Also, is this sort of spurious behaviour commonplace please?

If you have a 3m long antenna feeding a control signal to a powered servo then odd movements might reasonably be expected. Can't say I've ever tried it though.


Thanks Steve. I too am not surprised at the behaviour when disconnected. But although I've no direct evidence otherwise I'm hoping that "...when it is connected and operating the sketch normally" this presumably high impedance and high frequency mains noise will never matter?


Please understand your fluorescent lights each contain an ELECTRIC ARC that produces the UV light that excites the phosphors in the tube to produce what you see is white light. That ARC produces a wide band of electromagnetic noise. High impedance means it is MORE susceptible to the electromagnetic noise, not less.

Replace the fluorescent lights with LED lights.


You could try a screened lead feeding the servo , screened earthed at supply end to 0v .
Replaced the strip light with an led one !