How to use digital multimeter and tips
Digital multimeter is mainly based on the pointer multimeter, digital multimeter it is a digital voltmeter as the core of the device, the internal analogue circuit into a digital circuit, and the head is replaced with an LCD screen.
Digital multimeter, can measure DC current (A-), DC voltage (V-), AC current (A ~), AC voltage (V ~), resistance (Ω), (beeping gear), current amplification (HFE), gear (F), inductance block (H) can also be identified as a firewire, square wave gear, TTL logic level measurement gear, duty cycle measurements, frequency (Hz) measurements, conductivity nS and so on.
Usage:
Measure DC voltage, AC voltage, resistance, diode, transistor, capacitance, etc., insert the red pen into the VΩ hole and the black pen into the COM hole.
To measure current at mA level, insert the red pen into the mA hole and the black pen into the COM hole, the mA hole has a 200mA fuse.
To measure currents higher than mA level insert the red pen into the 20A or 10A current dedicated jack and the black pen into the COM hole.
The COM hole, also known as the common terminal, is the jack for inserting the black pen.
According to the measurement object, choose the correct gear and range.
Pay attention to the polarity of the meter pens, try not to connect the reverse.
Before measuring resistance, the two pens are shorted and adjusted to 0. The digital multimeter is popular among radio enthusiasts because it has the advantages of accurate measurement, convenient value, and complete functions, etc. The most common digital multimeter generally has the advantages of resistance measurement, pass-break sound detection, diode forward conduction voltage measurement. AC and DC voltage and current measurement, transistor amplification and performance measurement. Some digital multimeter is increased capacitance measurement, frequency measurement, temperature measurement, data memory and voice reporting and other functions, to bring great convenience to the actual test work. However, the digital multimeter due to improper use, in the actual detection is easy to cause damage to the table components, resulting in failure.
Digital multimeter damage in most cases is caused by the measurement of the wrong gear, such as in the measurement of AC utility, the measurement of the gear selection is placed in the resistance block, in this case, once the pen contact with the utility, instantly can cause damage to the internal components of the multimeter. Therefore, before using the multimeter to measure, you must check whether the measuring position is correct. At the end of the use, the measurement selection will be placed in the AC 750V or DC 1000V, so that in the next measurement, no matter what parameters are measured by mistake, will not cause damage to the digital multimeter.
Some digital multimeter damage is due to the measurement of voltage and current beyond the range caused by the range. Such as in the AC 20V gear measurement of utility power, it is easy to cause damage to the digital multimeter AC amplifier circuit, so that the multimeter to lose the AC measurement function. In the measurement of DC voltage, the measured voltage exceeds the measurement range, also easy to cause the table circuit failure. When measuring current, if the actual current value exceeds the range, it will only cause the fuse in the multimeter to blow, and will not cause other damages. Therefore, when measuring voltage parameters, if you don't know the approximate range of the measured voltage, you should first put the measurement gear in the highest grade, and then change the gear after measuring its value to get a more accurate value. If the voltage value to be measured is far beyond the maximum range that the multimeter can measure, it should be equipped with another high resistance measuring pen. Such as detecting the second anode high voltage and focusing high voltage of black and white colour TV.
The upper range of DC voltage of most digital multimeters is 1000V, so when measuring DC voltage, the maximum voltage value is below 1000V, which generally will not damage the multimeter. If it exceeds 1000V, it is likely to cause damage to the multimeter. However, different digital multimeters may have different upper limits of measurable voltage. If the measured voltage exceeds the range, it can be measured by resistor step-down method. In addition, in the measurement of 40O ~ 1000V DC high voltage, the pen and the measurement of the place must be in good contact, there can not be any jitter, otherwise, in addition to possible damage to the multimeter and make the measurement inaccurate, serious cases can also make the multimeter without any display.
