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DC Power supply. AC ~ 110V ± 10% 60 Hz. DC V out. R L. AC ~ 110V ± 10% 60 Hz. DC out. ?. R L. Zener diode shunt voltage regulator. V in. I = (V in -V z ) /R s. R S. Drawbacks: Heat V z fixed. V out = V Z. Example: V in = 12 V V z = 6 V I = 1 A W = 12 w. V Z. V in.
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DC Power supply AC ~ 110V ±10% 60 Hz DC Vout RL
AC ~ 110V ±10% 60 Hz DC out ? RL
Zener diode shunt voltage regulator Vin I = (Vin-Vz) /Rs RS • Drawbacks: • Heat • Vz fixed Vout = VZ Example: Vin = 12 V Vz = 6 V I = 1 A W = 12 w VZ
Vin Vout = VZ – 0.6 V I max = *I RS Ib VZ Add an emitter follower I
A convention Vin I RS Ib VZ
Adjustable Vout Vin I RS
R3 + R4 VBE R4 Using feedback Vout = +Vin Vout R1 R3 R4
R3 + R4 (VBE + Vz) R4 Improvement Vout = +Vin Vout R1 R3 R4
R4 Current limiting +Vin Vout
R2 + R3 VZ R3 Using an op. amp. Vout = +Vin R2 R1 R3 VZ
2 1 V+ in LM78 XX 3 Available XX : 05, 08, 09, 10, 12, 15, 18, 24 (V), and etc.
V- out V- in LM79 XX
Vout Vin LM117/317
n n p p Transistors A review of JFET n p
- + + + n + + + - Transistors MOSFET D G S - + - + SiO2 Al n-Si
+Vin Vout = R3 + R4 VBE R4 R1 Vout R3 R4