Question 3-32D4

Figure 3D9 depicts a standard series pass linear voltage regulator circuit. * **TR1 (NPN transistor)** is correctly configured as the series pass element. Its collector is connected to the unregulated input, and its emitter provides the regulated output. TR2 controls the base current of TR1. This is a common and functional design, making option C incorrect. * **D1 (Zener diode)** is correctly reverse-biased (cathode towards the positive unregulated input via R2, anode towards ground) to provide a stable reference voltage for TR2. This is essential for regulation. D2 is a standard diode often included for output protection (e.g., against reverse voltages from the load), and its orientation shown does not prevent the supply from functioning, making option B incorrect. * **R1** is connected in series with an LED from the regulated output to ground. Its purpose is to limit current to the LED, indicating power. It has no direct influence on TR1's base current or its destruction. TR1's base current is controlled by TR2. Therefore, option A is incorrect. Since none of the identified issues are actual problems, the circuit is correctly drawn and functional as a regulated power supply.