Kelvin 4 wire ,low frequency inductance tests

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Tubetec

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Nov 18, 2015
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I recently got an LCR bridge ,apart from having to make a new set of probe leads Im very happy with its performance so far .Once the differences between the four cables in terms of resistance ,capacitance and inductance  is minmised the the probe calibration functions as it should ,I still suspect the steel springs in the probes even though I insulated them ,of adding uneven capacities and inductances ,it is a coil after all ,so I might try some small elastics instead to keep the jaws shut and see if the readings are any more accurate .

One limitation is the fact that 100hz is the lowest frequency it measures
and theres no provision to set the Ac drive voltages either
Could  I  plug in another signal source into my bridge  ,  bypass the  the XJW01's internal dss or even drive the bridge directly  ,
Would a small microcontroled waveform generator be ok ?

https://www.ebay.co.uk/itm/FG085-Digital-MiniDDS-Function-Signal-Generator-DIY-Kit-Sine-Triangle-EU-Plug

That one might do the trick ,its around 30 euros kit form ,
proper cased two channel units are from about 50 euros upwards off ebay .

I'm also working on a cnc/stepper motor/ballscrew idea for neatly layering fine gauge wires on my coil winder ,
I have a couple of optical rotary encoders and a  motor control unit so hopefully I can get a clock signal from the encoders and use the function generator to do the mathematics of positioning the stepper motor .


Any advice greatly apriciated.

See schematic of LCR meter below ,


 

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