Electronic Components 1

Power Supply - Stage 1 Mains voltage has to be reduced

1 - Transformation

+

-

+

-

120 VAC

30 VAC

4:1

Electronic Components 2

Power Supply - Stage 2 Alternating voltage has to be converted to DC

2 - Rectification

Half wave rectification

Load

30 VAC

9.6 VDC

Electronic Components 3

Power Supply - Stage 2 Alternating voltage has to be converted to DC

2 - Rectification

Half wave rectification

Load

-9.6 VDC

30 VAC

Electronic Components 4

Power Supply - Stage 2 Alternating voltage has to be converted to DC

2 - Rectification

Full wave rectification

RL

30 VAC

19.1 VDC

Electronic Components 5

Power Supply - Stage 3 Fluctuating voltage has to be smoothed

3 - Filtered

RL

RL = 5.1 k

C = 33 F

Vout = 40VDC with 1V ripple

Electronic Components 6

Power Supply - Stage 3 (Filtering)

RLRS

When first turned on capacitor acts as a short. The surge current can damage

diodes. This can be reduced by adding a surge resistor.

Electronic Components 7

Power Supply - Stage 3 (Filtering)

RL

A more effective (although more costly) way is to use an inductor to oppose the changes in current. The capacitors in the LC filter oppose

changes in voltage.

Electronic Components 8

Power Supply - Stage 4 Voltage has to be smoothed further

4 - Regulation

Zener diode gives constant base voltage. Thus base current is constant and so will be the collector and emitter currents.

RL

Electronic Components 9

Graymark 808 Power Supply

Power supply was built from a kit.

Has two 0 - 15V and one 5V

Also has three protoboards

Ideal for doing analogue and digital lab projects

Electronic Components 10

Graymark Power Supply

Bottom plate shows transformer and circuit board

Circuit Board

Bottom plate

Transformer

Electronic Components 11

Graymark Power Supply

Circuit board

Rectifier diodes

IC regulator

Filter capacitor