How to use the voltmeter
1. Let's first get to know the digital voltmeter. Generally, the voltmeter has 3-4 terminals, one negative terminal (red terminal), and two to three positive terminals (black terminal).
Usage of voltmeter (learn how to use multimeter in one minute)
2. When measuring voltage, we should connect the voltmeter to both ends of the circuit to be measured; The positive and negative terminals must be correctly connected; The appropriate range shall be selected and the range of the voltmeter to be measured shall be confirmed in advance and shall not exceed the limit. In parallel in the circuit.
3. In the parallel connection test, the value obtained is displayed on the small window of the display screen, and the value is 1.570v.
4. We have already known the appearance and usage of digital voltmeter above. Here we will know the appearance of ordinary scale voltmeter.
5. Let's take the test of dry battery as an example to test the use of ordinary scale voltmeter: here, we will do the experiment in parallel to see the change of values.
6. The positive and negative pole connection should be correct, which is similar to the positive and negative pole terminal connection method of digital voltmeter; The range shall be correctly selected, and the range of the voltmeter to be measured shall be confirmed in advance, which shall not exceed the limit. Let's see that the final value on the dial does not change significantly.
7. Let's choose the voltage range 15V positive terminal to test. At 15V, each large cell on the dial is 5V, and each small cell is 0.5V; Let's see how many divisions the pointer has passed on the dial.
8. When we select the voltage range of 3V, each large grid on the dial is 1V, and each small grid is 0.1V; Let's see how many divisions the pointer has passed on the dial. The final value is 1.5 V. In case of series connection, the final measured result is the power supply electromotive force. The series and parallel methods are similar to each other.
How to use universal voltmeter
The voltmeter gear must be selected first, and the measuring range must be selected. If you do not know how much the measured voltage is, you should first set the gear to the highest voltage gear, and then adjust the gear. Never change gears with power on! When the voltage is higher than the measured voltage of the voltmeter, the "high voltage test rod" can be connected externally, with a configuration (the internal resistance is generally 5 megohm). The maximum measuring range is 25000 volts. The high-voltage test rod has three wires, the one with clamp is grounded, and one of the other two is directly connected to the rod tip for discharge. The other one cannot be inserted into the meter, and must not be inserted incorrectly. The multimeter is different from the multimeter. The multimeter has many functions, such as measuring voltage, current, resistance, diode, etc. The multimeter is only used to measure voltage. When it is used, the two leads of the meter are directly connected to the circuit to be measured, and the reading depends on the range. Instructions for use of multimeter:
1. Be familiar with the structural features and operation methods of the multimeter used according to the factory instructions and the actual objects, and check whether the instrument itself and accessories are in good condition. When not in use, the change-over switch should not stay on the "ohm" position to avoid battery discharge caused by accidentally shorting the probe. The instrument should be stored in a place where the environmental conditions meet the requirements, and the battery should be taken out when not in use for a long time.
2. Set the range switch according to the measured value, and find the scale read accurately. The range shall be selected so that the pointer points to 1/2~2/3 of the full scale. When the measured value is difficult to estimate, the range shall be gradually switched from large to small. When measuring the resistance, the zero ohm scale should be adjusted and checked every time the magnification is changed.
3. Safety precautions: when measuring resistance, the power supply of the circuit to be measured must be cut off before proceeding; Do not touch the metal part of the probe; When measuring voltage and current, live switch is not allowed; When measuring DC, pay attention to the correct polarity of the probe. When measuring high voltage, use the insulation test rod specially attached to the instrument, take insulation protection measures, and assign special personnel to monitor.
Use of voltmeter
Zero adjustment
And flow in and out
Unable to read the voltage to be measured, and the voltmeter is damaged
Maximum range, test connection, large range, small range
Unable to read the voltage to be measured, and the voltmeter is damaged
Small energy
How to use the voltmeter
The voltmeter has three terminals, one negative terminal and two positive terminals. We learned it in junior high school. Do you still know how to use the voltmeter? The following is how to use the voltmeter that I have arranged for you. I hope it will be helpful to you!
Usage of voltmeter
The positive and negative poles of the power supply should be correctly connected to the parallel circuit.
Pay attention to the link switch when connecting the voltmeter, and the switch should be disconnected.
The positive pole of the power supply shall be connected to the positive connection of the voltmeter, and the last connection part of the negative connection of the voltmeter is the negative pole of the power supply.
When reading the voltage value, read the voltage according to the selected range~put the instrument in order after the test~
Principle of voltmeter
Traditional pointer voltmeters and ammeters are based on the principle that the larger the current produced by the magnetic effect of the current, the greater the magnetic force generated, which shows that the larger the swing of the pointer on the voltmeter is, and there is a magnet and a wire coil in the voltmeter. After passing the current, the coil will generate a magnetic field, and the coil will rotate under the action of the magnet after being energized, This is the head of ammeter and voltmeter.
Since the voltmeter must be connected in parallel with the measured resistance, if a sensitive galvanometer is directly used as a voltmeter, the current in the meter will be too large, and the meter will burn out. At this time, a large resistance needs to be connected in series in the internal circuit of the voltmeter. After this transformation, when the voltmeter is connected in parallel in the electrical circuit, due to the effect of resistance, Most of the voltage applied to both ends of the meter is shared by the resistance in series, so the current passing through the meter is actually very small, so it can be used normally.
A "_" shall be added under V for the symbol of DC voltmeter, and a "~" shall be added under V for the symbol of AC voltmeter.
Voltmeter structure
A voltmeter is a large resistor, ideally an open circuit. A voltmeter (in parallel with other electrical appliances) and electrical appliances are connected in parallel in the parallel circuit. If there are no other electrical appliances in the main circuit, it can be considered as measuring the power supply voltage (because all electrical appliances on the parallel circuit enjoy the power supply voltage); If other consumers are connected in the trunk, the consumer shares part of the power supply voltage, and the voltmeter can only measure part of the voltage (which consumer is connected to which consumer is the voltage of which consumer).
You should know that there is a magnet and a wire coil in the voltmeter. After passing the current, the coil will generate a magnetic field, so that the coil will rotate under the action of the magnet after being energized, which is the head part of the ammeter and voltmeter.
