@Shannon how difficult do you think it would be to implement a special electrolytic capacitor testing mode? Electrolytic caps are polarized, and thus the correct way to test them is (I think) to bias the test signal to the Vpp/2 level, so that it always stays above zero instead of the standard AC signal of +/- Vpp/2.
I'm not sure what difference it will make though, but it just seems to me that applying a reverse polarity voltage to electrolytic caps, even if low and only for a half period, isn't quite right -- might be from the cap damage or the measurement precision perspective, or both. There are some LCR meters that implement this biased signal mode, e.g. East Tester ET432/433. I'm not able to find any good info on this topic, only vague suggestions that it's "better" to test the electrolytics with a positively biased signal, and it gives better precision.
It would be great to have that.
Also, as I was looking for a LCR Tweezer before Tautech told me about Shannon's one, here is the LCR-MPA function table, which I think may be added for some of them (the blue one would be great ) ?
@ceut @shapirus Thanks for your information
The effect of DC bias on capacitance is a standard spec for those ceramic capacitors, electrolytic capacitors, etc.
It may not be easy to implement because a table is usually used to describe it. Taking ceramic capacitors as an example,
The abscissa of a chart is the DC voltage value, and the ordinate is the loss of capacitance. Therefore, when we consider providing DC bias, we need to implement an adjustable and wide-range DC bias voltage, which is reasonable.
However, as a low-power high-precision device, ST42 is basically unlikely to provide a higher DC bias, because the operating voltage of the core device is 3.3V.
We also checked the parameters of the EST43 series and found that the internal bias is adjustable, but the adjustable range is 0~500mV. Such a bias range is also difficult to meet real test requirements.
The most common application in my mind, what is the capacitance of the capacitor under 12V/5V/3.3V/1.8V DC bias.
But you all know, when you know one cap value of two serial cap and the serial cap total value, you can calculate the other cap value.
This principle could help you measure the DUT cap under any DC bias voltage. This test method makes me feel exited