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university:courses:alm1k:alm-lab-led-sensor [06 May 2019 14:55] – [Background:] Doug Merceruniversity:courses:alm1k:alm-lab-led-sensor [24 Mar 2022 16:13] (current) – [Step 2 Directions:] Doug Mercer
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-======Activity: LED as light sensor ======+======Activity: LED as light sensor, For ADALM1000======
  
 =====Objective:===== =====Objective:=====
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 =====Step 2 Directions:===== =====Step 2 Directions:=====
  
-Change the circuit on your breadboard to the Darlington configuration shown in figure 2. Be sure to turn off the power supply before making any changes to the circuit. With the Darlington connected transistors the emitter current of Q<sub>2</sub> becomes the base current of Q<sub>1</sub> such that the photo generated current from the LED D<sub>1</sub> is now multiplied by ß<sup>2</sup> and will appear in the load resistor R<sub>L</sub> from the collectors of Q<sub>1</sub> and Q<sub>2</sub>. Because of this much higher current gain we can use a much lower value load resistor.+Change the circuit on your breadboard to the [[wp>Darlington_transistor|Darlington configuration]] shown in figure 2. Be sure to turn off the power supply before making any changes to the circuit. With the Darlington connected transistors the emitter current of Q<sub>2</sub> becomes the base current of Q<sub>1</sub> such that the photo generated current from the LED D<sub>1</sub> is now multiplied by ß<sup>2</sup> and will appear in the load resistor R<sub>L</sub> from the collectors of Q<sub>1</sub> and Q<sub>2</sub>. Because of this much higher current gain we can use a much lower value load resistor.
  
 ====Step 2 Procedure:==== ====Step 2 Procedure:====
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 ====Questions:==== ====Questions:====
  
-How well does the red LED respond to the various light sources? Does it respond to another red or yellow or green LED used as a light emitter? How about the yellow and green LEDs? Is the infrared LED sensitive to the same or different wavelengths of light compared to the visible light LEDs? Which is the most sensitive to standard household lights such as incandescent and compact florescent bulbs?+How well does the red LED respond to the various light sources?\\ Does it respond to another red or yellow or green LED used as a light emitter?\\ How about the yellow and green LEDs?\\ Is the infrared LED sensitive to the same or different wavelengths of light compared to the visible light LEDs?\\ Which is the most sensitive to standard household lights such as incandescent and compact florescent bulbs?
  
-How does the sensitivity of the Darlington connected configuration compare to the single common emitter configuration? Are the minimum and maximum voltages the same for both configurations? If not why?+How does the sensitivity of the Darlington connected configuration compare to the single common emitter configuration?\\ Are the minimum and maximum voltages the same for both configurations? If not why?
  
 **For Further Reading:** **For Further Reading:**
  
-https://en.wikipedia.org/wiki/LED\\ +[[wp>LED|LEDs]]\\ 
-https://en.wikipedia.org/wiki/LED_circuit\\ +[[wp>LED_circuit|LED circuits]]\\ 
-https://en.wikipedia.org/wiki/Photodiode+[[wp>Photodiode|Photo diodes]]
  
-**Return to ALM Lab Activity [[university:courses:alm1k:alm-labs-list|Table of Contents]]**+**Return to [[university:labs:intro_ee|Introduction to Electrical Engineering]] Lab Activity Table of Contents**\\ 
 +**Return to [[university:courses:alm1k:alm_circuits_lab_outline|Circuits]] Lab Activity Table of Contents**
  
university/courses/alm1k/alm-lab-led-sensor.1557147307.txt.gz · Last modified: 06 May 2019 14:55 by Doug Mercer

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