Diode 2 Unidirectional current characteristics Permit current to - PowerPoint PPT Presentation

Diode 2

Unidirectional current characteristics  Permit current to flow through in one direction (when forward-biased ), but not the other ( reverse-biased ). 3

Transformer 4

Transformer 240 V 5

Part A + 240 V v in - + v in - L out 6

Part A: Half-Wave Rectifier (HWR) 240 V  A rectifier is an electrical device that converts alternating current (AC) to direct current (DC). 7

Part A: Full-Wave Rectifier (FWR) 240 V 8

Part B: Filter Capacitor 240 V L out 9

Electrolytic Capacitor  The polarity is almost always indicated by a printed band.  The lead nearest to that band is the cathode lead (-).  Additionally, the positive lead is usually longer.  Hook them up the wrong way and at best, you’ll block the signal passing through. At worst (for higher voltage applications) they’ll explode. Also check that it is 100-  F 50-V 11

Oscilloscope: DC vs. AC    Input signal: v t      DC mode: Show  v t v t DC      AC mode: Show   V v t v t DC AC  v AC ( t ) always have 0 average (theoretically)      when V DC = 0.  v t v t AC DC 12

In DC mode… Not enough to move the interesting part of the waveform into the screen 13

Part C: Bridge rectifier 17