Multimeter - phase tester circuit principle

Kaixin micro test

Test - lowercase jpg

Test probe PH-5H

The Pocket Digital Multimeter does not have the L, C measurement function, even if the portable digital meter does not have an additional L function. The additional instrument cooperates with the DT-830B, that is, it can measure L or measure the circuit. The measuring range of the inductor is 0.1Uh-2H, divided into six files, the minimum resolution is 0. UH, and the precision is within 2%. The measurement range of C is 0.1pF~1μF, divided into four steps, the minimum resolution is 0.1pF, and the accuracy is about 1%.
The circuit for measuring the capacitance C is as shown in the figure, and is composed of a double D flip-flop CD4013 or the like. Adjust the capacitance above 200pF, the digital meter uses DC 2V file, and separately correct the standard capacitance of each range with the accuracy of 1%; and measure the capacitance within 200pF, apply the 100pF capacitor within 1% and then use the digital meter 200mV file. measuring. At this time, the range switch should be in the 1nF position. If the layout of the circuit is reasonable, the minimum stray capacitance is about 3pF.
As shown in the circuit wield, the L circuit is measured. IC1a, IC1b and resistors, capacitor crystals, etc. constitute a 500khz intermediate frequency oscillator. If input is not divided, the minimum range is 20μH.