Measurement of MOS Field-Effect Transistors (MOSFETs) Using a Digital Multimeter
There are domestically produced 3D01, 4D01, and Nissan's 3SK series for N-channel. Determination of G-pole (gate): Use the diode mode of the multimeter. If the positive and negative voltage drops between one foot and the other two feet are both greater than 2V, it will display "1", and this foot is the gate G. Swap the probes again to measure the other two feet. In the case where the voltage drop is small, connect the black probe to the D terminal (drain) and the red probe to the S terminal (source).
1, Voltage range:
When testing or manufacturing, it can be used to measure the voltage of each pin of the device, and compare it with the normal voltage to determine whether it is damaged. It can also be used to detect the voltage regulation value of a voltage regulator diode with a smaller voltage regulation value. The principle is shown in the diagram: R is 1K, and the voltage at the power supply end depends on the nominal voltage regulation value of the voltage regulator tube. Generally, it is more than 3V higher than the nominal voltage, but not more than 15V. Then use a multimeter to detect the voltage value at both ends of the D tube, which is the actual voltage regulation value of the D tube.
2, Current range
Connect the meter in series into the circuit to measure and monitor the current. If the current deviates far from the normal value (based on experience or existing normal parameters), the circuit can be adjusted or repaired if necessary. You can also use the 20A range of this meter to measure the short-circuit current of the battery, by directly connecting the two probes to both ends of the battery. Remember not to exceed 1 second in time! Attention: This method is only applicable to dry batteries, 5th and 7th rechargeable batteries, and beginners should be guided by personnel familiar with maintenance. Do not operate on your own! The performance of the battery can be judged based on the short-circuit current. In the case of a fully charged battery of the same type, a higher short-circuit current is better.
3, Resistance mode;
One of the methods that can be used to judge the quality of resistors, diodes, and transistors. If the actual resistance value of the resistor deviates too much from the nominal value, it has been damaged. For a transistor with two or three poles, if the resistance between any two pins is not very high (several hundred K or more), it can be considered that the performance has decreased or has been broken down and damaged. Note that this transistor does not carry resistance. This method can also be used for integrated blocks. It should be noted that the measurement of integrated blocks can only be compared with the parameters under normal conditions.
4, Nowadays, the probes of ordinary multimeters have high resistance values. Interested enthusiasts can make their own set of probes; Method: Prepare a high-quality speaker cable or multi-core copper wire of about one meter, a pair of insulated clips (red and black), and a pair of banana plugs (red and black) for speaker wiring; One end of the wire is welded firmly onto the clamp, and the other end is correspondingly inserted into the banana plug; A good pair of pens is a great achievement.
