Pointer multimeter for the measurement of voltage regulator diodes
Voltage regulator is generally greater than 1.5V, and the pointer meter R × 1k below the resistance of the meter is powered by a 1.5V battery, so that the R × 1k below the resistance of the measurement of the regulator tube as a diode, with a complete unidirectional conductivity. But the pointer meter R × 10k file is powered by 9V or 15V battery, in the R × 10k voltage regulator value less than 9V or 15V regulator, the reverse resistance will not be ∞, but a certain resistance, but this resistance is still much higher than the forward resistance of the regulator. In this way, we can initially estimate the good and bad voltage regulator.
However, a good voltage regulator to have an accurate value of the voltage regulator, amateur conditions how to estimate the value of the voltage regulator? Not difficult, and then go to find a pointer table on it. Method is: first a table placed in the R × 10k file, the black and red pens were connected to the cathode and anode of the regulator, which simulates the actual working state of the regulator, and then take another table placed in the voltage file V × 10V or V × 50V (according to the value of the regulator) on the red and black pens were connected to the table just now that the black and red pens, the measured voltage is basically the regulator's Regulated value.
Said "basically", because the first table on the voltage regulator bias current relative to the normal use of the bias current is slightly smaller, so the measured value of the voltage regulator will be slightly larger, but the basic difference is not large. This method can only be used to estimate the regulated value of the regulator that is less than the voltage of the high-voltage battery of the pointer gauge. If the regulator's regulated value is too high, you can only use the method of external power supply to measure (so it seems, we choose the pointer table, select the high-voltage battery voltage of 15V is more applicable than 9V).
Semiconductor diode test method shown in Figure 1, the multimeter set R × 100 or R × 1k block. With a multimeter negative pen (battery + end) connected to the diode "+" pole; positive pen connected to the diode "-" pole, that is, to the diode to apply a positive voltage, the diode is in the conduction state, the meter reads the value of its forward resistance If the diode under test is a silicon diode, the meter will read its forward resistance value. If the measured silicon diode, the meter pointer in the middle of the surface or a little to the right of the middle, it shows that the forward characteristic is good. Then the positive and negative pens inverted, positive pens connected to the diode "+" end, negative pens connected to the diode "-" end, then the diode with a reverse voltage, in the cut-off state, for the silicon tube, the needle is almost immobile, that is, the resistance value About ∞; if the measured germanium diode, the resistance of the two characteristics are small. The results of the two tests as described above, indicating that the tube has a unidirectional conductive properties, indicating that the tube under test is intact. Otherwise, it is a bad tube.
To determine the polarity of a diode, through the above two tests, the first to identify its good or bad. As long as the tube is intact, if the measured result is a small resistance value, said the measured resistance is positive, then the negative pen of the multimeter connected to the end of the diode is the "+" pole (remember that the negative pen of the multimeter is the table within the battery E's + end); if the measured resistance value is large, then the negative pen is connected to the diode's " -" pole.
