1. Component Selection By Prof. Bitar

2. Power Supply Example Input: 120VAC / 60Hz (nominal) Output: 5V +/- 5%(4.5 to 5.5 V) 100mA (max)

3. Possible Full-Wave Topologies (Assuming Linear Voltage Regulators)

4. Typical Voltage Waveforms

5. Begin Distributor Part Search for “Voltage Regulators”

6. Yikes! Only 41,864 Possibilities… 41,864 Possibilities!

7. Narrow the Search! In Stock !!! 6,241 Linear

8. Further Search Criteria Current (100mA) Package / Case (TO-92 Thru-Hole!) Packaging (for shipping) Topology (Positive Fixed) Voltage (5V)

9. Down to Mfg & Pricing (Note Sorting Criteria) Fairchild Semiconductor$0.32 (More $, but better spec sheets & support.) Micro Commercial Co:$0.20 (Not as well supported, but CHEAP!)

10. Selecting Part-Number Link Yields More Information Including Price Breaks! Finally a Data Sheet!

11. Component Data Sheet Absolute Maximum Ratings (Not to be exceeded !!) Input Voltage Max (30V) Operating Temp (-20 to 120 C) Storage Temp (-55 to 150 C) Electrical Characteristics (Under very specific test conditions!) Output Voltage (4.8 to 5.2 V @ T = 25 C) Load Regulation (ΔV OUT / Δ I LOAD ) (60mV MAX from 1 to 100mA) Line Regulation (ΔV OUT / Δ V IN ) (150mV MAX, Vin from 7 to 20V) Quiescent Current (5.5mA MAX) Output Noise Voltage (40uV TYPICAL) Ripple Rejection (41dB MIN) Dropout Voltage (1.7V TYPICAL)

12. Q: Does this Voltage Regulator Meet our Specifications? YES! OK, Repeat this Process for Every Component… Power Transformer Diodes Filter Capacitors

13. Selecting a Power Transformer Questions: 1.What voltage do we need? 2.What is the maximum current? 3.What configurations do we need? 4.What configurations are available? Single or Dual Primary Single or Dual Secondary

14. 1. What Voltage Do We Need? Desired DC Output = 5V Minimum Drop Across Regulator = 1.7V (spec) Maximum Ripple Voltage = 1V (guess) Drop Across Rectifier Diodes = 0.7 or 1.4V Therefore, for C.T. Transformer: Vpk = 5+1.7+1+0.7 = 8.4V = 5.9V RMS Or for Full-Wave Bridge: Vpk = 5+1.7+1+1.4 = 9.1V = 6.4V RMS OK, Looking for 6.4V RMS @ 100mA (min)

15. Parts Distributor Search

16. Possible Choices Tamura 3FS212 : 6.3VAC, 180mA Transformer $3.75

17. Transformer Spec Sheet

18. Electrical Specifications

19. Mechanical Specifications

20. Hole Pattern Spacing

21. Configuration Options

22. Available Voltages / Currents