Pointer and digital multimeters - advantages and disadvantages
Pointer multimeter is a kind of average-value type instrument, it has intuitive, image of the reading instructions. (General readings are closely related to the angle of swing of the pointer, so it is very intuitive).
Digital multimeter is an instantaneous style instrument. It uses 0.3 seconds to take a sample to show the measurement results, sometimes each time the sampling results are only very similar, not exactly the same, which is not as convenient as the pointer to read the results.
Pointer multimeter generally no internal amplifier, so the internal resistance is small, such as MF-10 type, DC voltage sensitivity of 100 kilohm/volt, MF-500 type DC voltage sensitivity of 20 kilohm/volt.
Digital multimeter due to the internal use of op amp circuit, the internal resistance can be made very large, often in 1M ohms or greater. (i.e. higher sensitivity can be obtained). This allows for a smaller effect on the circuit under test and a higher measurement accuracy.
Pointer multimeter due to the smaller internal resistance, and more discrete components to form 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 lower, fewer functions, simple maintenance, over-current over-voltage capability is stronger. Digital multimeter internal use of a variety of oscillation, amplification, crossover protection and other circuits, so more functions. For example, it can measure temperature, frequency (in a lower range), capacitance, inductance, do signal generator and so on.
Digital multimeter due to the internal structure of more integrated circuits, so the overload capacity is poor, (but now some have been able to automatically shift gears, automatic protection, etc., but the use of more complex), after the damage is generally not easy to repair. Digital multimeter output voltage is low (usually no more than 1 volt). For some voltage characteristics of special components of the test inconvenience (such as silicon controlled, light-emitting diodes, etc.).
Pointer multimeter output voltage is higher, (10.5 volts, 12 volts, etc.). 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.
