IRF840 Datasheet & Price | Circuit Diagram, Pinout & Specifications Vishay Siliconix

IRF840 circuit

The IRF840 is an N-channel Mos tube that is cutoff when there is no voltage at the gate and conducts when a voltage is applied to the gate. He is mainly used in some high-power applications, such as switching power supply, motor drive, etc..

This circuit is a high-frequency oscillator that mainly uses a timer to control the IRF840 on and off, which in turn generates an LC resonant loop. The main principle is that when the timer input is high, the gate voltage rises, and then the IRF840 conducts, and the current flows from the power supply through the IRF840 and then through the inductor L1, forming a power supply loop. Timer input low level, the gate voltage becomes low, transistor cutoff, but there is still current in inductor L1, it will form a reverse electromotive force, the current will pass through the capacitor C4 to form an oscillation loop.