How metered and digital multimeters differ
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.).
