Multimeter: Tips for Measuring Zener Diodes
The voltage regulation value of the voltage regulator we usually use is generally greater than 1.5V, and the resistance range below R × 1k of the pointer meter is powered by the 1.5V battery in the meter. Therefore, measuring the voltage regulator with a resistance range below R × 1k is like measuring a diode, with complete unidirectional conductivity. But the R × 10k range of the pointer meter is powered by a 9V or 15V battery. When using an R × 10k to measure a voltage regulator with a voltage value less than 9V or 15V, the reverse resistance value will not be ∞, but will have a certain resistance value, but this resistance value will still be much higher than the forward resistance value of the regulator. In this way, we can preliminarily estimate the quality of the voltage regulator. However, a good voltage regulator also needs an accurate voltage regulation value. How to estimate this voltage regulation value under amateur conditions? It's not difficult, just find another pointer table. The method is to first place a meter in the R × 10k range, with its black and red probes connected to the cathode and anode of the voltage regulator, respectively, to simulate the actual working state of the voltage regulator. Then take another meter and place it in the voltage range V × 10V or V × 50V (depending on the voltage regulation value), and connect the red and black probes to the black and red probes of the meter just now. At this point, the measured voltage value is basically the voltage regulation value of this voltage regulator. The reason for saying 'basically' is that the bias current of the first meter for the voltage regulator is slightly smaller than the bias current during normal use, so the measured voltage regulator value may be slightly larger, but the difference is not significant. This method can only estimate the voltage regulator that is lower than the voltage of the high-voltage battery on the pointer meter. If the voltage regulation value of the voltage regulator is too high, it can only be measured by applying an external power source (it seems that when choosing a pointer meter, using a high-voltage battery voltage of 15V is more suitable than 9V).
