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2. An Automatic Night Light uses a photocell to detect the amount of available light in a room. Under strong light the resistance of the photocell is 1kn but goes up to 100k2 in total darkness. The photocell is put in series with a 4.7k2 resistor so as to make a voltage divider when the ends are connected between +5V and GND as shown. As it gets darker in the room, the resistance of the photocell goes up and raises the voltage on the "Sensor Voltage" line. At "dusk", the photocell has a resistance of 10kN. Automatic Night Light 5v vdd What will the range of the sensor voltage be the photocell а. +5V goes from 1kN (bright light) to 100k2 (total darkness)? Photocell Sensor Voltage LM358AD b. Write the equation for VoUT expressed in terms of the op-amp Vout U1A mmarceau 5V inputs and gain. What is the maximum range for VoUT? Reference Voltage (V) R4 34.7ka White LED c. Assuming the light is to come on at "dusk", what must the POTENTIOMETER reference voltage be set to to have the LED come on? SR3 d. If the white LED has a VF of 3.0V @ 10mA, what would be a suitable value for R3?

2. An Automatic Night Light uses a photocell to detect the amount of available light in a room. Under strong light the resistance of the photocell is 1kn but goes up to 100k2 in total darkness. The photocell is put in series with a 4.7k2 resistor so as to make a voltage divider when the ends are connected between +5V and GND as shown. As it gets darker in the room, the resistance of the photocell goes up and raises the voltage on the "Sensor Voltage" line. At "dusk", the photocell has a resistance of 10kN. Automatic Night Light 5v vdd What will the range of the sensor voltage be the photocell а. +5V goes from 1kN (bright light) to 100k2 (total darkness)? Photocell Sensor Voltage LM358AD b. Write the equation for VoUT expressed in terms of the op-amp Vout U1A mmarceau 5V inputs and gain. What is the maximum range for VoUT? Reference Voltage (V) R4 34.7ka White LED c. Assuming the light is to come on at "dusk", what must the POTENTIOMETER reference voltage be set to to have the LED come on? SR3 d. If the white LED has a VF of 3.0V @ 10mA, what would be a suitable value for R3?

Delmar's Standard Textbook Of Electricity
Delmar's Standard Textbook Of Electricity
7th Edition
ISBN:9781337900348
Author:Stephen L. Herman
Publisher:Stephen L. Herman
Chapter7: Parallel Circuits
Section: Chapter Questions
Problem 3PP: Using the rules for parallel circuits and Ohmslaw, solve for the missing values....
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2. An Automatic Night Light uses a photocell to detect the amount of available light in a room. Under strong light the resistance of the photocell is 1kn but goes up to 100k2 in total darkness. The photocell is put in series with a 4.7k2 resistor so as to make a voltage divider when the ends are connected between +5V and GND as shown. As it gets darker in the room, the resistance of the photocell goes up and raises the voltage on the "Sensor Voltage" line. At "dusk", the photocell has a resistance of 10k2. Automatic Night Light 5v Vdd a. What will the range of the sensor voltage be as the photocell +5V goes from 1k2 (bright light) to 100k2 (total darkness)? Photocell b. Write the equation for VoUT expressed in terms of the op-amp Sensor Voltage LM358AD Vout U1A mmarceau 5V inputs and gain. What is the maximum range for Vour? Reference R4 24.7ka Voltage (V) White LED C. Assuming the light is to come on at "dusk", what must the POTENTIOMETER reference voltage be set to to have the LED come on? SR3 d. If the white LED has a VF of 3.0V @ 10mA, what would be a suitable value for R3?
Transcribed Image Text:2. An Automatic Night Light uses a photocell to detect the amount of available light in a room. Under strong light the resistance of the photocell is 1kn but goes up to 100k2 in total darkness. The photocell is put in series with a 4.7k2 resistor so as to make a voltage divider when the ends are connected between +5V and GND as shown. As it gets darker in the room, the resistance of the photocell goes up and raises the voltage on the "Sensor Voltage" line. At "dusk", the photocell has a resistance of 10k2. Automatic Night Light 5v Vdd a. What will the range of the sensor voltage be as the photocell +5V goes from 1k2 (bright light) to 100k2 (total darkness)? Photocell b. Write the equation for VoUT expressed in terms of the op-amp Sensor Voltage LM358AD Vout U1A mmarceau 5V inputs and gain. What is the maximum range for Vour? Reference R4 24.7ka Voltage (V) White LED C. Assuming the light is to come on at "dusk", what must the POTENTIOMETER reference voltage be set to to have the LED come on? SR3 d. If the white LED has a VF of 3.0V @ 10mA, what would be a suitable value for R3?
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