Electronics Basics #12 | Zener Diode: The Voltage Regulator (Intro + Worked Example)

Instructor: Dr. Süleyman Burak ÇELİK

Meet the diode whose job is to hold a voltage perfectly steady. We turn what we always called a failure — reverse breakdown — into a precise voltage reference, then use it to build a real regulator. What you'll learn: - Why a Zener is "controlled" reverse breakdown, and why the voltage stays almost constant at V_Z - The water-tank-and-weir picture: level = voltage, weir height = V_Z, overflow = Zener current - The one test you must run every time: remove the Zener, find the divider voltage V = V_i · R_L/(R + R_L), and compare it to V_Z Worked example (V_i = 16V, R = 1kΩ, V_Z = 10V, P_Z(max) = 30mW), every step shown: - (a) R_L = 1.2kΩ → divider 8.73V is below 10V → Zener OFF: V_L = 8.73V, V_R = 7.27V, I_Z = 0, regulation lost - (b) R_L = 3kΩ → divider 12V is above 10V → Zener ON: V_L = 10V, V_R = 6V, I_R = 6mA, I_L = 3.33mA, I_Z = 2.67mA, P_Z = 26.7mW is below 30mW (safe) The takeaway: test first, then trust. Reference: Boylestad, Electronic Devices and Circuit Theory