Servos and Teensy

Servos and Teensy

Following on from How electrically noisy are Servo motors – Pt1 where I subjected a Tower Pro MG996R and a Tower Pro Microserver 9g to the ERAD (Emissions Radiated) test. I am now going to do the ECON (Emissions Conducted) test.

The ECON test is a scan between 150 kHz and 30 MHz.

Like ERAD there are two sets of emissions limits that are most commonly tested for (others are more specialist requirements), the graphs below will only have the class B Limits on them, Class A limits are above Class B.

The Limits for Residential, Commercial and Light Industrial emissions are specified in Table 2 of BS EN 61000-6-3:2007 (class B):

  • 15 kHz to 0.5 MHz – 66 to 56 dB mV Quasi Peak, 56 to 46 dB mV Average Peak
  • 0.5 MHz to 5 MHz – 56 dB mV Quasi Peak, 46 dB mV Average Peak
  • 5 MHz to 30 MHz – 60 dB mV Quasi Peak, 50 dB mV Average Peak

The Limits for Industrial emissions are specified in Table 2 of BS EN 61000-6-4:2007 (class A):

  • 15 kHz to 0.5 MHz – 79 dB mV Quasi Peak, 66 dB mV Average Peak
  • 0.5 MHz to 30 kHz – 73 dB mV Quasi Peak, 60 dB mV Average Peak

The code for testing the servos was the same as the previous post, however rather than try to use a battery source; I used the Thurlby linear power supply for all the tests.

The mains power for Thurlby was taken via the LISN (Line Impedance Stabilization Network) and the emissions on the power cable were recorded.

Graph 1: Background

Graph 1: Background

Graph 2: TowerPro Micro Servo 9g

Graph 2: TowerPro Micro Servo 9g


Graph 3: TowerPro MG996R

Graph 3 – TowerPro MG996R

For Conducted I didn’t even need to do any measurements for Quasi Peak, or Average Peak analysis as all emissions recorded were within the limits set by BS EN 61000-6-1.