| 摘要 |
<p>The Darlington transistor circuit presents three stages and comprises a power transistor (T3), a driver transistor (T2) and an input transistor (T1). The collectors of those three transistors are interconnected, while the transmitter of the driver transistor (T2) is connected to the base of the power transistor (T3) and the transmitter of the input transistor (T1) is connected to the base of the driver transistor (T2). The base of the driver transistor (T2) is also connected to a terminal of a first resistor (R1) of which the other terminal is connected to the anode of a Zener diode (ZD). On the base-transmitter junction of the driver transistor (T2) there is mounted in parallel a second resistor (R2). Due to the presence of the Zener diode (ZD) and of the two resistors (R1, R2), the driver transistor (T2) and the power transistor (T3) become passing transistors when obtaining a given voltage on the cathode of the Zener diode (ZD), while the variation, as a function of the temperature, of such insertion voltage is determined by the ratio between those two resistors.</p> |
