I would like to do some current sensing, i would like to know if cheap current transformers like the the SCT-013s as good as abit more pricier onnes on digikey, what should stop me from making my own? The SCT-013 are already relatively cheap but i can go even further and ordering a core and winding some magnet wire on it (it might be tiring to wind so many turns but its cheap).

One of the reason that some might be expensive is because of the built in amplifier i understand that, but if what if i already have those on my adc front end, even the burden resistor, and just want the coil. I could not think of a possible downside since there are very few parts, a core and a wire.

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    \$\begingroup\$ What sort of bandwidth do you want? That's the biggest thing I've personally encountered that mandates (extremely) expensive CTs; if you need multi-hundred-MHz bandwidth, you can't get by with anything short of a Pearson. \$\endgroup\$
    – Hearth
    Jul 13, 2021 at 0:34
  • \$\begingroup\$ @Hearth im only using it for mains voltage frequency 50-60Hz. but of course current of devices are not really at that frequency, i think 1kHz is enough. \$\endgroup\$
    – Jake quin
    Jul 14, 2021 at 16:10

1 Answer 1


Does dynamic range, effective turns ratio from loses, rise time, bandwidth, DCR, linearity, phase shift error and temperature error of magnetic material matter?

Yes of course quality matters and your specs matter the most to determine if it is possible to meet your expectations for the application.

  • one used for 50 MHz 50 Ohm is far different than one for 50 Hz. What should stop you from making your own?

  • A lot of experience is necessary for choosing from the vast array of magnetic material properties and winding ratios with saturation currents, excitation voltages and choice of high mu with an air gap or low mu with more distributed magnetic particles etc.

Reading lots of reports and knowing how to test these current sources is a learning experience that should never be underestimated. When you understand what matters write a good spec then go shopping. Maybe you end up with 3 current sensors , one with nano particles and one with silicon steel and another with a Kelvin 50mV bridge.

  • \$\begingroup\$ sadly i can only afford the cheap ones, im using it for current sensing off the wall, about 50-60Hz frequency, but of course current is not 50-60Hz too. 1kHz - 10Khz maybe? is the SCTs will be enough for that>? the articles shows its performance, linearity seems good, phase error i dont really have much experience if that is good, \$\endgroup\$
    – Jake quin
    Jul 14, 2021 at 16:18
  • \$\begingroup\$ Current phase error affects cosine product of VI or power factor or real power measurement. Any sensor is only as good as you can calibrate it with a better one. \$\endgroup\$ Jul 14, 2021 at 19:31

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