Precautions for using field-effect transistors

The precautions for using field-effect transistors are as follows:

(1) For the safe use of field-effect transistors, the maximum dissipation power, maximum drain source voltage, maximum gate source voltage, and maximum current of the transistor should not be exceeded in the design of the circuit.

(2) When using various types of field-effect transistors, they must be strictly connected to the circuit according to the required bias, and the polarity of the field-effect transistor bias must be observed. If the gate source drain of a junction field-effect transistor is a PN junction, the gate of an N-channel transistor cannot be biased positively; The gate of the P-channel transistor cannot be biased negatively, etc.

(3) Due to the extremely high input impedance of MOSFETs, the lead pins must be short circuited during transportation and storage, and metal shielding packaging must be used to prevent external induced potentials from breaking down the gate. Special attention should be paid to not placing MOS field-effect transistors in plastic boxes. It is best to store them in metal boxes and also pay attention to moisture resistance of the transistors.

(4) In order to prevent gate induction breakdown of field-effect transistors, it is required that all testing instruments, workbenches, soldering irons, and circuits themselves must have good grounding; When soldering the pins, solder the source first; Before connecting to the circuit, all lead terminals of the diode should be kept in a short circuited state with each other, and the short-circuit material should be removed only after welding is completed; When removing the diode from the component rack, it should be ensured that the human body is grounded in an appropriate manner, such as using a grounding ring; Of course, if advanced gas thermal soldering iron can be used, it is more convenient to solder field-effect transistors and ensure safety; Never insert or remove the diode from the circuit without turning off the power. The above safety measures must be taken into account when using field-effect transistors.

(5) When installing field-effect transistors, it is important to avoid placing them as close to heating elements as possible; In order to prevent vibration of the pipe fittings, it is necessary to tighten the pipe shell; When bending the pin lead, it should be made 5mm larger than the root size to prevent bending the pin and causing air leakage. For power type field-effect transistors, good heat dissipation conditions are required. Because power type field-effect transistors are used under high load conditions, sufficient heat sinks must be designed to ensure that the housing temperature does not exceed the rated value, allowing the device to operate stably and reliably for a long time.

In short, to ensure the safe use of field-effect transistors, there are various precautions to be taken and various safety measures to be taken. Professional and technical personnel, especially electronic enthusiasts, should take practical and feasible measures based on their actual situation to use field-effect transistors safely and effectively.