Current meter modified to single-phase AC voltmeter ----- AC Voltmeter

Current meter modified to single-phase AC voltmeter, AC Voltmeter Keywords: current meter modified to single-phase AC voltmeter Current meter modified to single-phase AC voltmeter Author: Li Jinghui The method described herein can be modified into a single-phase AC voltmeter of a desired range without using the internal resistance of the current meter, which is shown in Figure 1. First, the working principle, because the current meter is a magnetoelectric meter, only tens of micro-DC current can be measured, or the tiny DC voltage can be indirectly measured (ug = IGRG, the UG is voltage, Ig For the current, Rg is the internal resistance of the meter). How do I use a single-phase AC voltage with a larger range? There are two points that you need to do: (1) The AC electricity needs to be changed to DC; (2) The measurement is required to expand the measurement (as shown in the drawings). The positive electrode of the sensitivity current gap is connected to a crystal diode Vd, and the alternating current is changed to DC, and one partial voltage resistor R is connected in series on the positive electrode of the crystal diode to enlarge the scale. two. Production of a common rotating potentiometer of 0 ~ lmΩ, power is 2W, rectified crystal diode 1N5395, O ~ 300V voltage regulator (single-phase AC voltmeter monitored by output voltage I), power switch and 250 micro-safety Current meter, connected according to Figure 2. The resistance value of the potentiometer is adjusted in advance to 1 MΩ. The output of the pressure regulator transformer is 300V (as can be known from the monitoring meter), the closed switch S, if the G table is not swinged to the maximum scale, indicating that the value of the value of the potentiometer is sufficient (otherwise replacing the resist value) Potentiometer). Slowly turn the potentiometer RP, indicate the maximum scale to the maximum scale, which indicates 300V of the alternating current. Disconnect, at this time, the resistance of the potentiometer is measured at this time, and an alternate potentiometer is accessed by the measured resistance (about 380kΩ). In order to make the dial more dedicated, the drawn G dial can be removed, copy a new dial with a white cardboard or other material. The above is the whole process of the current meter modified into single-phase AC voltmeter. This method can make any current meter (header) of different sensitivity, and modified a single-phase AC voltmeter of the desired range. Of course, if the current is converted into a DC voltage meter, you can use a resistor on the current meter to expand its range. In addition, after the voltage meter is changed, the scale of the dial is also required, and the G-table can be used in the original scale and maximum scale, modified into the corresponding OV and 300V, and then pass the calibration, make the minimum scale of other voltage values. I.e.