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I have the following circuit to plot X-Y plot in an Oscilloscope to get Hysteresis curve. enter image description here
R2 and C2 are kept so that the cutoff frequency of low pass filter formed is less than 2Hz.

   1
------- < 2*π*(2Hz)
(R2*C2) 

The circuit is realized using a Transformer with two input and output terminal pairs. One of the input and output terminal pairs are kept open while plotting the X-Y plot.

Now, if I short the output terminal that was kept open, what will happen to my hysteresis loop in the oscilloscope? Could you please explain?

Following circuit is expected after shorting. enter image description here

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  • 3
    \$\begingroup\$ Your hysteresis loop will be reduced to a hysteresis line :) \$\endgroup\$ – Dmitry Grigoryev Mar 23 '17 at 16:23
  • \$\begingroup\$ @DmitryGrigoryev Could you please why there is no significant current through C2? \$\endgroup\$ – Jithin Pavithran Mar 23 '17 at 17:13
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You'll see essentially a horizontal line on your X-Y plot, because Y is now zeroed out and the X is still measuring current (although it will probably see more current because the impedance through the transformer is lower).

Probably not a good way to test things, here is another way to test transformers

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  • \$\begingroup\$ Basically no current will flow through R2? How is that explained while the coil is still in changing magnetic field? Could you please draw some light on this as well? \$\endgroup\$ – Jithin Pavithran Mar 23 '17 at 16:32
  • \$\begingroup\$ If you place a shorting resistor across the terminals at e2, then no current will go through R2, one thing to keep in mind is that a real transformer also has parasitic capacitance and resistance. The capacitance probably won't be a big deal for most power (60Hz and most DC to DC) applications, but the resistance will. \$\endgroup\$ – Voltage Spike Mar 23 '17 at 16:37
  • \$\begingroup\$ Added a figure to reduce ambiguity. My shorting doesn't introduce anything in e2 terminals. \$\endgroup\$ – Jithin Pavithran Mar 23 '17 at 16:49
  • \$\begingroup\$ That changes everything \$\endgroup\$ – Voltage Spike Mar 23 '17 at 17:16
  • \$\begingroup\$ I'm sorry for any miscommunication. I mean to short the unused output terminals of the transformer (I mentioned it to be two input two output transformer). Could you please explain now? \$\endgroup\$ – Jithin Pavithran Mar 23 '17 at 17:21

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