【 Weak current College 】 (universal table) the use of a multimeter (part two) 】

Digital multimeter inside the structure is simple so a lower-cost less-functional-easy maintenance capacity-overvoltage and strong.
Digital multimeter inside using several oscillations, magnify. crossover. protection circuits therefore function more like can measure temperature. frequency (at a lower range). capacitance, inductance. or do signal generator, and so on.
Due to the internal structure with integrated circuits so overload capacity is poor. (But now some have automatic shift. automatic protection, etc., but use more complex). damaged easily repair after General.
Digital multimeter low output voltage (typically no more than 1 v). for some voltage characteristic special symbol test inconvenience (as, SCR, light-emitting diodes, etc.)
Digital multimeter output voltage is high (10.5 Volt, 12 volt, etc).
Current is large (such as MF-500 * 1-stall maximum 100 MA or so) you can easily test the SCR, light-emitting diodes, etc.
For starters, you should use the digital multimeter.
For a non-starter, you should use the two instruments.

Figure 1: analog multimeter Photo 2: digital multimeter


Considerations for use of a multimeter


(1) before using a multimeter for "mechanical zero", i.e. in the absence of measured power, the multimeter pointer means zero voltage or zero current location.
(2) when using a multimeter, not a hand to touch the metal parts of the table amount, so that we can ensure accurate measurement, on the other hand it can guarantee the security of the person.
(3) measured with a power that cannot be measured at the same time shift, especially when measuring high voltage or high-current, more attention should be paid. Otherwise, the multimeter destroyed. If you need to shift, you should disconnect the shift table pen, then go to the survey.
(4) multimeter when used, must be horizontal, so as to avoid the error. At the same time, we must pay attention to avoid outside the influence of magnetic field on the multimeter.
(5) multimeter after use, set the switch on the AC voltage Max. If you do not use long, should also be multimeter battery inside out, so as to avoid battery corrosion in other devices.


The use of the ohmmeter


First, select the appropriate rate. In the measurement of resistance, ohm meter would be on the appropriate rate, so that the pointer indicates the value in the vicinity. It is best not to use the scale on the left third of the section, this section scale-intensive is poor.
2. use the former to zero.
3. measurement cannot be charged.
Fourth, the measured resistance cannot have parallel branches.
5. measurement of transistors, electrolytic capacitors, etc. have polarity symbol equivalent resistance, it should be noted that two pens of polarity.
6. use a different rate of multimeter ohmmeter measure nonlinear components equivalent resistance, the measured resistance values are different. This is due to the shift in resistance and full of current varies, mechanical watches, the smaller the general rate, measured resistance.