Does the true rms value of a multimeter matter?
Ordinary pointer multimeter or digital multimeter for high-frequency voltage, current measurement are frequency range. Beyond the frequency range they are unable to correctly reflect the true RMS value of high frequency waveforms. It will be clear when you look at the technical specifications of your multimeter.
What is True RMS?
Only a True RMS meter can accurately measure voltage/current. It's average value meter measures AC signals by the grate method: average of measured values x 1.11 = corrected to RMS. True RMS The algorithm for an AC signal measured by a True RMS meter is: Root Mean Square algorithm = True RMS. For pure sine wave, no matter true RMS or average value meter can be measured accurately, but for non-sine wave such as: square wave, triangle wave, sawtooth wave, only true RMS meter can be measured accurately. Many of today's electronic loads that undergo a frequency change are non-sinusoidal, and having a true RMS multimeter is the only way to accurately measure the correct value.
How to measure and read resistance with a multimeter
In the repair of electronic circuit boards, circuit boards whose resistive components account for about 50% of the entire electronic components, if the circuit has a fault resistive components are one of the components we have to measure.
So how to use a multimeter to measure resistance and read the number of resistance? Below I give you the problems in this regard, before measuring resistance we had better carry out two zeroing operations, one is the pointer multimeter mechanical zeroing; the second is the ohm zeroing. After the operation of these two steps you can choose the appropriate resistance multiplier for resistance measurements, due to the multimeter resistance file scale is not uniform, we choose the multiplier file generally want to make the pointer scale stays in the sparse part of the scale is the best, and the closer the pointer is to the middle of the scale position the more accurate. I suggest that it is best to make the pointer in the scale of 1/3 to 2/3.
Reading Methods
The method of reading the multimeter is not complicated, that is, the reading of the meter head is multiplied by the multiplier, that is, the resistance value of the resistor to be measured. For example, to measure the resistance value of a resistor is 47 ohms, then the range to "Rx10" on the ohms file, then Hou multimeter pointer points to the position of 4.7, the final reading is 4.7x10 for 47 ohms. If the measurement of large resistors can choose a larger resistance range, such as Rx1k or Rx10K, they read the resistance value of the same method.
