1. BE Lesson 11: AC to DC power supply What is an AC to DC power supply? What is a rectifier? What is an RC filter? What is a regulator? © 2012 C. Rightmyer, Licensed under The MIT OSI License, 20 July 2012

2. What’s a AC to DC adapter? Sometimes called a DC power supply?

3. AC voltage and current go both positive and negative I = I max sin  [Intro to College Physics, Appleton-Century-Crofts, R.D. Rusk, 1960]

4. Power supply design requirements Step down transformer Pulsating DC rectifier Capacitive filter Voltage regulator ACV in DCV out Transformer AC output designed to support power supply maximum DC output voltage V o DC 1. 2 v 35. 0 v

5. Full wave rectifier and its output voltage pattern [Building Power Supplies, Master Publishing Inc, David Lines, 1991 120 V AC +12 V AC -12 V AC

6. How does a diode operate in a circuit? + Forward voltage drop ~ 0.7 volts Maximum reverse voltage = 50 volts Adapted from http://www.kpsec.freeuk.com/components/diode.htm -

7. Smoothing the output with an RC filter [Building Power Supplies, Master Publishing Inc, David Lines, 1991

8. Ripple voltage after RC filtering [Building Power Supplies, Master Publishing Inc, David Lines, 1991

9. BE demo 11-1 (a). AC Sinewave voltage pattern Center Tapped Transformer 120 VAC 6 VAC Oscilloscope

10. BE demo 11-1 (b). AC Sinewave voltage pattern Center Tapped Transformer 120 VAC 6 VAC 1N4001 1K Oscilloscope

11. BE demo 10-1 (c). Pulsed DC voltage pattern. Center Tapped Transformer 120 VAC 1N4001 1K Oscilloscope

12. BE demo 11-1 (d). Smoothed Pulsed DC voltage Center Tapped Transformer 120 VAC 12 VAC 1N4001 1K Oscilloscope 470 uF

13. BE demo11-1 (e). Measured DC output voltage Center Tapped Transformer 120 VAC 12 VAC 1N4001 1K 470 uF DC Voltmeter 8.5 volts

14. BE demo 11-1 (f). Regulated 5 volt output Center Tapped Transformer 120 VAC 12 VAC 1N4001 1K 470 uF DC Voltmeter 5 volts UA7805 5 vDC output

15. BE demo 11-2. An Improved DC power supply with adjustable DC output voltage LM 317 12 VAC 120 VAC 12 VAC C1 C2 C3 R1 R2 R3 LED D1 D2 VoVo T1 T1: 24v secondary, 2 amps D1, D2: 1N5400 R1: 220, 1/4 watt R2: 240, 1/4 watt R3: 5k pot, 1/2 watt C1, C2: 2200uf, 50v C3: 0.1uf, 50v Adj Out In 317 Adj Out In