Question

v3 sP19 HW 9 Name Sec. 1 a) What is an LED and how does it differ from a rectifier diode? b) What is the typical voltage drop across a display LED? c) What is a typical current for a display LED? d) Is the LED a polarity sensitive device? If it doesn't light what is the 1s thing that should be done? 2. a) When light enters a Photo Transistor what is Vc? b) When there is no light what is Vc? c) Explain how LED/Photo Transistor works.OPB732 Photo- transistor/LED d) What is advantage of using LED/Photo Transistor vs just Photo Transistor to detect RC car?

Answer 1

Comparison chart (a) Basis for comparison . LED Diode 1 . Definition Type of diode which when placed in an electric field emitf light It is a semi - conductor diode which conductor only in one direction . 2 . Symbol 3 . Material GaAs (Gallium Arsenide) & Gap (Gallium phospide) silicon and Germanium 4 . Reverse Breakdown voltage low High 5 . Application emits Light converts Acto DC \r\n 6 . principle LED converts energy into light . Diode converts energy into Heat . 7 . user indicator's in 7 - segment displays, use as a light source Rectifiers, Voltage multipliers, clamping etc . (b) Typical voltage drop Aeolus LED = 1.8 ti 3.3 volts (c) Typical current through display LED = 20 mA (d) Yes, LED is a polarity sensitive Device