Differences in the selection of pointer multimeters and digital multimeters
1, pointer table reading accuracy is poor, but the pointer swing process is more intuitive, the swing speed amplitude can sometimes be more objective to reflect the size of the measured (such as measuring the TV data bus (SDL) in the transmission of data when the slight jitter); digital table readings are intuitive, but the process of digital change looks very messy, not very easy to watch.
2, pointer table generally have two batteries, a low-voltage 1.5V, a high-voltage 9V or 15V, its black pen is positive relative to the red pen. Digital meter is commonly used a 6V or 9V battery. In the resistance file, the pointer meter pen output current relative to the digital table is much larger, with R × 1Ω file can make the speaker emit a loud "da" sound, with R × 10kΩ file can even light up the light-emitting diode (LED).
3, in the voltage file, the pointer table internal resistance is relatively small compared to the digital table, the measurement accuracy is poorer. Some high-voltage micro-current occasions can not even be measured accurately, because of its internal resistance will affect the measured circuit (for example, in the measurement of the accelerated stage voltage of the TV tube when the measured value will be much lower than the actual value). The internal resistance of a digital meter's voltage range is very high, at least on the megohm scale, and has very little effect on the circuit under test. But the very high output impedance makes it susceptible to the influence of induced voltage, in some electromagnetic interference is relatively strong occasions measured data may be false.
4, in short, in relatively high-current, high-voltage analogue circuit measurements in the application of pointer gauge, such as televisions, audio amplifiers. In the low-voltage small-current digital circuit measurements in the application of digital meters, such as beepers, mobile phones and so on. Not **, according to the situation can be selected pointer meter and digital meter.
