What is the frequency of oscillation in lc100-a?

The frequency of oscillation in the LC100-A is about 500kHz when measuring a 1nF capacitor or a 100uH inductor. To get that tiny bit of driving power to resonate into a sinusoidal signal with 1V peak-to-peak amplitude requires a “high Q” LC circuit - both the inductor and the capacitor.

What size inductor does the lc100-a use?

The published schematics for the LC100-A suggest that the inductor should be 100uH; But many units came with inductors that measure from 47 to 56uH. The LC100-A requires a reference inductor with its highest Q between 70-700kHz.

How do LC tank circuits work?

The “driving signal” for the LC tank circuit is a 5V peak-to-peak square wave from the LM311 is fed back into the LC tank circuit through a 100k ohm resistor (R5 on schematic)---a VERY small signal (50uA). The frequency of oscillation in the LC100-A is about 500kHz when measuring a 1nF capacitor or a 100uH inductor.

How accurate is the lc100-a?

This single alteration improved the accuracy of the LC100-A to better than +/-2% measuring a large number of capacitors from 10pF up to 100nF. The published schematics for the LC100-A suggest that the inductor should be 100uH; But many units came with inductors that measure from 47 to 56uH.

What happens if a LC circuit has no resistance?

Similarly, the oscillations of an LC circuit with no resistance would continue forever if undisturbed; however, this ideal zero-resistance LC circuit is not practical, and any LC circuit will have at least a small resistance, which will radiate and lose energy over time.

What amplitude should a Minghe lc100-a be?

Larger is better. Ideally it should be 300-500mV RMS, 1V peak-peak. On a "genuine MingHe" LC100-A, amplitude is 430mV RMS, 1.25V peak-peak, but with the the yellow inductor from the "unbranded generic" LC100-A, the oscillation is only 40mV RMS, 128mV peak-peak.