MAGNETIC COIL DRIVER CIRCUIT

摘要

A pair of transistors are connected to opposite ends of the magnet coil to be energized. A control pulse directly turns one transistor on and simultaneously fires a single shot multivibrator and its output turns on the other transistor. Current builds up in the coil during the single shot multivibrator time out period. The transistor controlled by the single shot multibivrator turns off when the single shot multivibrator times out. Coil current decreases but at slow rate as it circulates from one side of the power supply through a diode connected to one end of the coil and through the transistor connected to the other end of the coil back to the same side of the power supply. The dropping of the control pulse turns off the other transistor and the coil current rapidly decays to zero because the power supply is connected across the coil in a reverse direction via another diode connected to the other end of the coil and the other side of the power supply.