The higher the resistance of the multimeter, the higher the output voltage will be?
For pointer multimeter resistance gear output voltage, basically equal to the voltage of the battery in the meter. For example, MF47 type Rx1 ~ RX1K is 1.5V, Rx10K is 9V. MF10 type R x1 ~ R x10K is 1.5V, R x 100K 15V.
However, these output voltages of the same gear, due to different circuit design, internal resistance is not the same, resulting in the ability to output current to the outside is not the same. The higher the gear the lower the current. For example, a tungsten bulb will glow when measured with Rx1, but not when measured with Rx1K or higher. But for LED lamp beads, because the on-state voltage is above 1.8v, although Rx1 can output a large current, it still can't light it up. On the contrary, with 9v, 15v battery Rx10K or 100K file, even if the current is very small, but also allows the LED lamp beads to conduct and emit a very weak light.
Digital multimeter is different, because the meter has an amplifier, but also to reduce the meter's power consumption, so the resistance file output voltage is very low. 9205-type table, for example, 200Ω ~ 20MΩ output voltage is only a few volts, only the diode file and 200M file voltage is slightly higher.
Diode file for the breakthrough PN junction cut-off area, the output no-load voltage is generally more than 2.5v, the pen short-circuit current is more than 1mA. 200MΩ file, due to the current through the measured resistance is too small, in order to obtain enough sampling voltage drop, the output voltage is about 1.5v, but the pen short-circuit current is less than 5μA.
So the output voltage of the multimeter resistance gear is not gradually increased with the gear changes, but to meet the normal work of the multimeter to arrange.
Pointer multimeter internal 1.5V battery and a 9V battery, the role of these two batteries is dedicated to the resistance file power supply, that is to say, even if you remove these two batteries, the pointer multimeter, DC voltage file, AC voltage file, DC current file can be measured, because these three files are through the external circuit to be measured to absorb the signal, after the internal voltage-sharing resistor, shunt resistor, voltage-sharing / shunt / rectifier. Shunt / shunt / rectifier, unified to go to the meter head to measure, only the resistance file only with internal battery as a power source, the pointer multimeter resistance file is designed using the principle of voltammetric resistance, that is to say, according to the size of the current flowing through the resistor to measure the size of the resistor, we know that the resistor has the role of impeding the current, according to this reason to measure the size of the resistor, that is to say, if the resistor resistance is measured the larger the current flowing through the resistor is the same as the current flowing through the resistor. That is to say, if the resistance value of the measured resistor is larger, the current flowing through the measured resistor is smaller, then the angle of deflection of the pointer is also smaller, indicating that the measured resistance is very large, and vice versa, if the resistance value of the measured resistor is smaller, then the current flowing through the measured resistor is larger, then the angle of deflection of the pointer is also larger, indicating that the measured resistance is very small, designed by this principle of the resistance file.
R×10K is powered by internal 9V battery in the pointer multimeter. R×1K R×100 R×10 R×1 are powered by internal 1.5V.
Digital multimeter, diode gear open-circuit voltage, that is, the VΩ hole and COM hole voltage of 2.5V-2.8V or so, and resistance gear open-circuit voltage of all ranges are 0.3V-0.6V or so, and the current of each gear is indeed different, this point needs to be measured by yourself!
