用指针式万用表对场效应管进行判别（Identification of field effect transistor with pointer multimeter）.doc

用指针式万用表对场效应管进行判别（Identification of field effect transistor with pointer multimeter） First, the field effect tube is distinguished by a pointer type multimeter (1) the electrode of junction type FET is determined by measuring resistance According to the phenomenon that the PN junction of the field effect transistor is different from the positive and reverse resistance values, the three electrodes of the junction type FET can be determined. Specific method: dial the multimeter on the R * 1K file, select two electrodes, and measure the positive and negative resistance values respectively. When the positive and negative resistance values of two electrodes are equal to several thousand ohms, the two electrodes are drain D and source S respectively. Since the drain and source are interchangeable for the junction type FET, the remaining electrode must be the gate G. Can also be a multimeter black pen (red pen also) free to contact an electrode, another pen in order to contact the rest of the two electrode, measuring the resistance value. When the resistance two times the measured value is approximately equal when the electrode is in contact with the black pen to the gate, the other two electrodes respectively drain and source. If the two measured resistance value were large, that is both PN junction reverse, reverse resistance, can determine the N channel field-effect tube, and the black pen is connected with the gate; if the two measured resistance value is very small, that is a positive PN junction, is determined to be P positive resistance, ditch channel FET, the gate is connected the black pen. If such a situation can change black and red pen testing according to the above method, identify the gate until now. (2) determine the quality of the field effect transistor by measuring resistance Measure resistance is measured with a multimeter resistance FET between source and drain, gate and source, gate and drain, gate and G1 gate G2 FET resistor value with the manual indic