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Registered Member #1497
Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801
The intended application is for monitoring my capacitor bank's current waveform, the coil itself gives dI/dt, the change in current over time, and the integrator is just a couple of opamps, some features are just to play around with to see if its useful at all.
I just completed the integrator, although I have a few wires to hook up, it looks promising. In a few days I will have the time to completely wire the input/output connectors and test the integrator. The waveforms you see above are dI/dt, I'll try to get a captured waveform soon, and only calibration is left to finish.
Another bonus is that it would appear that the output is reduced in voltage, I may have to add a separate gain stage with a 1x, 10x, 100x selection switch just to get the desired amplitude...
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529
On my PC, The drop is low enough that the time has to be on the lowest setting on the dial, and sometimes lower. I don't think a gain stage is necessary.
Registered Member #195
Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111
a lot of thease ciols are pure inductance and may have there own resonant frequencies. if you use a core and spread the windings apart and add a parallel noninductive resistor your response will be more flat. the core bandwidth will detrmin the frequency response. person probes are made this way I believe
hey aenomous, about the schematic diagram, how do u actually plan it? like im planning to use my coil just for instrumentation. perhaps having a frequency of 1kHz is enough.
so do u think my schematic diagram will be as complicated as yours? if i were to use 741 op amp model, could i just use 2 resistors r1,and r2, and a capacitor c1,
with the capacitor and r2 feeded back to the opamp and r1 is in series with the input?
hi guys. Is it possible if any of u could give me advice online? I have built my own rogowski coil using a 75 ohms co-axial cable about a meter long.
I have wind it up using a wire and turn in 282 times around the coil. I plan to use it for instrumentation purposes.
The voltage range that i have decided is = 1mV - 10V and operating current range to be = 1mA - 1A. the frequency range should be about = 1Hz - 1kHz
i have then make my own calculations, to get the integrator value, which is
Calculations E = H di/dt H= munaught N A N= 1762.5 turns/m Radius of the coil = 2 x 10-3 Cross sectional Area A = Pi r^2 = 1.26 x 10^-5 Mu naught = 4 pi x 10^-7 So H = 27.9 nVs/A ---------ïƒ coil sensitivity
Say Vout = 10 V, I = 1 A
then
Vout = IH/CR CR = 27.9/10 = 2.79 If R = 10000 ohms, then C = 2.79/10000 = 0.000279 F = 279 x 10^-6 Farad
does that makes any sense ?
also yesterday i tried my soundcard as an integrator to produce waveform using soundcard as a DSO. I used winscope and online oszilloscope but to no avail. I couldnt get it to work.
I have got pictures of my coil and everything. If any of u r interested i could email it to you, then maybe u could help me figure out what went wrong.
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Rogowski coil construction
