Looking to get some help with this circuit since it doesnt seem to be doing what I am expecting it to do although I will admit my expectations may be wrong.
Background:
Im looking at implementing a project where I can use the output of a rogowski coil, this one the JRF-2, and change it to a current output based on the voltage. For a range of 0-668mV on the rogowski I wanted to get 0-1A out of the circuit, although if I was able to get 0-5A out that would be the best. For some reason I am only getting about 14mA. The LPF is in there to attenuate anything above 60Hz.
How I chose the components:
For the LPF I just did RC=1/(2*pi*f) and then came up with a RC pair that worked. I did do a sweep simulation on the frequencies that performed pretty much as I expected.
As for the op-amp portion, I always get just under 15V out and depending on the input voltage around 14mA. I looked at the data sheet for the LT1210 and it said the Av gain was 71dB. So I worked that backwards and got an Av of 3548 with Av(dB)=10^(71/20). I saw that the filter was attenuating so I had found that at 668mV my actual input would have been 455mV so I multiplied that by 1.25 to account for overshoot and whatnot. So with vi of 0.56875 I got Av=vo/vi, so vo was 2018. For the op-amp the gain is Av=1+(Rf/Ri) so found a Rf/Ri pair that you can see in the circuit. From here I run the simulation and nothing really seems to be working like I expect.
Thank you for the help guys.
Background:
Im looking at implementing a project where I can use the output of a rogowski coil, this one the JRF-2, and change it to a current output based on the voltage. For a range of 0-668mV on the rogowski I wanted to get 0-1A out of the circuit, although if I was able to get 0-5A out that would be the best. For some reason I am only getting about 14mA. The LPF is in there to attenuate anything above 60Hz.
How I chose the components:
For the LPF I just did RC=1/(2*pi*f) and then came up with a RC pair that worked. I did do a sweep simulation on the frequencies that performed pretty much as I expected.
As for the op-amp portion, I always get just under 15V out and depending on the input voltage around 14mA. I looked at the data sheet for the LT1210 and it said the Av gain was 71dB. So I worked that backwards and got an Av of 3548 with Av(dB)=10^(71/20). I saw that the filter was attenuating so I had found that at 668mV my actual input would have been 455mV so I multiplied that by 1.25 to account for overshoot and whatnot. So with vi of 0.56875 I got Av=vo/vi, so vo was 2018. For the op-amp the gain is Av=1+(Rf/Ri) so found a Rf/Ri pair that you can see in the circuit. From here I run the simulation and nothing really seems to be working like I expect.
Thank you for the help guys.
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