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LCR Meter Plot Software
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mawyatt:
Think this file is 680uF_ESR.

These are what's reported when one plots Rseries of a "Cseries and Rseries" capacitor model and are computed by the LCR meter from the magnitude and phase of the voltage and current of the DUT. All the electrolytic, ceramic, film and polymer types we've evaluated exhibit this Equivalent Series Resistance decreasing with frequency over this frequency range.

Thanks for the thumbs up, but think we have a long way to go before being able to do anything somewhat serious code-wise!! Altho this has really augmented the Tonghui TH2830 into a level of a much more expensive class of Lab LCR meter which can produce nice plots vs. frequency without resorting to a spread sheet and CVS files, same for the Hioki IM3536, altho it started out pretty expensive, but does cover 8MHz!!

Anyway, just grabbed about 20 various caps of all sorts and sizes and did a frequency sweep per the plot, and took maybe 10 minutes all toll, and the graphs looked nice as well!! Now we've got the external DC sweeping capability and enabled the IM3536 DC built-in capability, now curiosity has us thinking about a tiny temp chamber to "sweep" temperature also. We've seen and plotted how bad the high dielectric ceramics are with voltage, might be interesting to see how well they standup over temperature as well as some of the plastic films types, maybe even some PN junctions ::)


Best,
RoGeorge:
Temperature behavior would be interesting.

I would expect the ESR to get lower while increasing the temperature.  Saying this because electronics that are malfunctioning because of bad ESR caps might still start and run when the caps are heated with hot air, but won't start when the caps are cold.  No idea what to predict about the resonant frequency.


About making a temperature chamber, only couple of weeks ago I've measured a very weird behavior from a power resistor that kept heating for hours while under constant voltage.  It was not much power and small size, would have expect to settle in minutes at most, not hours.  Turned out the resistor was pumping heat into the rubber mat that was covering the workbench, which rubber mat was keep heating slowly by conduction from the power resistor.  When suspended in air, same resistor comes to thermal equilibrium very fast.

My point is, I expect small thermal inertia to be more important than being a good thermal insulator when choosing the materials for making a thermal chamber, or else the temperature might settle too slow.  Or maybe just Capton-tape a temperature probe to the capacitor and don't wait for the temp chamber to stabilize.  If the instrument measures fast enough relative to the temperature slope, then it all can be done while heating/cooling, without waiting for the temperature to stabilize.


Still can't find any decent argument for why the ESR will go lower with frequency.  Will have to read more about ESR, then hook a capacitor and an oscilloscope to the AWG to get a grip of it.


Thank you for sharing these results.
mawyatt:
Not an expert on capacitor design/construction and their behavior, if you find something on such please share.

Agree the low thermal mass is the way to go, and maybe doing a ramp to the highest temperature, then allowing DUT to return to ambient while recording parameters during temperature decent with removing heating source. Since we aren't interested in going below ambient or highly accurate & stable temperature, this just requires heating and no TEC.

One simple idea is to use a chunk of metal heated on a plate with DUT and thermistor taped to surface, then allowed to cool when plate removed and parameters recorded.

Another is to use a small PCB heating device like the MPH30 and taping the DUT to the small plate along with a thermistor. If we were good at microcontroller & coding (as shown we are not!!!), then one could write some custom firmware for the MPH30 to allow remote operation (this has a USB C port for power and upgrades, so maybe could be reconfigured for remote control)?

Another is a using a power resistor with flat surface area (like panel mount types, or cheap ceramic long square types), tape DUT and thermistor to power resistor. This could be placed within a "Closed Control Loop" by means of a controlled power supply within the measurement routine.

Anyway, lots of options for doing some temperature sweeps (maybe other types or combinations) now we've gathered a "handle" on controlling these LCR meters from Python and utilizing the nice plotting capability.

Lots of options to consider if we only had the time ::)
 
Best,

mawyatt:
Well we can't evade curiosity, and have little patience, kind of a curse from the beginning ???

So grabbed a 10W ceramic 10 ohm resistor, the common long square type, and decided to use this as a temperature "chamber". Put some thermal tape along the top and mounted a K type thermocouple along with the DUT which were a couple disc ceramic capacitors. 100nF cheap 50V type and another 10nF 1KV "Blue" disc, don't know the ceramic material type but from the plots these are from the high dielectric constant types, then tried a 220nF mylar film type, which is much more stable, and a 1nF Mica type. Finally a 100uF Polymer Type.

The setup uses a TH2830 LCR meter, with a SDP3303X Power Supply and SDM3065 with a "K" Type thermocouple for reading the 10W ceramic resistor temperature. Set the voltage and current limits to 10V and 1A to keep the resistor within 10W rating, this produces a standing (on leads as shown) resistor temperature top range of >100C. The thermocouple and DUT were held in place by the thermal tape and a plastic clamp as shown, the cardboard U shaped piece is to keep the plastic clamp from melting!!

A Python routine was created to sweep the PS voltage, read the resistor temperature, then read the LCR parameters, adapted from the previous DC Sweep routines.

Anyway, this kludge actually works reasonably well and at least shows how the capacitance of different types varies with temperature. Still need to work on the Python routine and such, but this did satisfy our curiosity ::)

Edit: Added 1000uF 16V Cap

Best
mawyatt:
Ran a couple more devices just for fun while working in the yard. A small 1mH inductor, 10nF Mylar (cheap flat Green type) cap and a 1N4148 diode. Inductor and Diode measured at 100KHz, Cap at 1KHz.

Geeze, see we can't even spell temperature properly in all the graphs  :palm:

Please use the conversion factor 1 degrees C temparture = 1 degrees C temperature  :-+

Best,
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