How dial indicators differ from digital multimeters
Pointer multimeter is a kind of average value type instrument, it has intuitive, image of the reading instructions. The digital multimeter is an instantaneous style instrument, it uses 0.3 seconds sampling results are only very similar, not exactly the same, read the results is not very convenient.
Pointer multimeter generally has no internal amplifier, so the internal resistance is small, such as MF-10 type, DC voltage sensitivity of 100 kilo-ohm/volt. The MF-500 has a DC voltage sensitivity of 20 kOhm/volt. The digital multimeter, on the other hand, can be made to have a large internal resistance due to the internal op amp circuit. Often in 1M ohms or greater, which makes the impact on the measured circuit can be smaller, higher measurement accuracy.
Pointer multimeter due to the small internal resistance, and more discrete components constitute a shunt and voltage divider circuit. So the frequency characteristics are uneven (relative to digital), while the frequency characteristics of the pointer multimeter is relatively good.
Pointer multimeter internal structure is simple, so the cost is low, fewer functions, simple maintenance, over-current over-voltage capability is strong. The digital multimeter internal use of a variety of oscillation, amplification, frequency division, protection and other circuits so more functions, such as temperature measurement. Frequency (in a lower range), capacitance, inductance, or signal generator and so on. Due to the internal structure of more integrated circuits, so the overload capacity is poor, after the damage is generally not easy to repair.
Pointer multimeter output voltage is higher, the current is also large (such as MF-500 * 1 ohm gear maximum of 100 mA or so) can be convenient to test the SCR, light-emitting diodes and so on. The digital multimeter output voltage is low (usually not more than 1 volt). For some special voltage characteristics of the components of the test inconvenience (such as, silicon controlled, light-emitting diodes, etc.).
Cautions
1> Measurement of current and voltage can not choose the wrong gear. If the wrong resistance gear or current gear to measure the voltage, it is very easy to burn the meter. When the multimeter is not in use, it is best to rotate the gear to the highest level of AC voltage to avoid damage due to improper use.
2>When measuring current and voltage and DC current, pay attention to the polarity of "+" and "-" and do not connect the wrong one. If you find that the pointer begins to reverse, both should immediately switch the meter stick to avoid damage to the pointer and the meter head.
3>If you don't know the size of the measured voltage or current, you should use the highest grade first, and then choose a suitable grade to test, so as not to damage the meter head by excessive deflection of the needle. The closer the selected gear is to the measured value, the more accurate the measured value will be.
4>When measuring the resistance, do not touch the bare ends of the components (or the metal parts of the two bars) with your hands, so as to avoid the parallel connection of the human body resistance and the measured resistance, which will make the measurement result inaccurate.
5> Measurement of resistance, such as the two bars shorted, adjust the "zero ohm" knob to the maximum, the pointer is still not up to 0, this phenomenon is usually caused by insufficient voltage of the battery inside the table should be replaced with new batteries can be measured accurately.
6>When the multimeter is not in use, do not select the resistance gear, because there is a battery inside, such as accidentally easy to make the two bars touch the short circuit, not only consume the battery, but also in serious cases, even a short circuit. This will not only consume the battery, but also damage the meter head in serious cases.
