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New page: = Lab 4 - Sensors, Semiconductors = == Topics == * Potentiometers, photoresistors, variable resistance. * Transistors == Supplies == * TIP-120 transistor. * Bulb. * 10K potentiometer. * P...
= Lab 4 - Sensors, Semiconductors =
== Topics ==
* Potentiometers, photoresistors, variable resistance.
* Transistors
== Supplies ==
* TIP-120 transistor.
* Bulb.
* 10K potentiometer.
* Pliers, strippers, clippers.
* Hookup wire.
* Jumper kit (short pre-cut wires).
* Breadboard.
* Power Supply.
* Multimeter.
== Activities ==
* Explore the behavior of your potentiometer. Is the relationship between rotation + resistance linear? ("linear" vs "exponential" taper)
** What is the measure between "A" and "B"? does it change as your turn the knob?
** Record and plot the rotation of the knob and resistance at a few points. Is the relationship between them linear? ("linear" or "expontential" taper)
[[Image:Potentiometer_labelled.jpg| 300px]][[Image:Variable_resistance.png | 300px]]
* Wire up a simple voltage divider using your potentiometer and a 10K resistor, conected to the 5V supply.
** How does the output voltage vary as you turn the knob? (measure at the point between the potentiometer and the resistor)
* Photoresistor as variable resistance
** measure the "light" resistance of your photoresistor
** measure the "dark" resistance. (cover the resistor with your hand, or try shutting it in one of the lab cabinets)
** setup up a voltage divider with the photoresistor and a 10K resistor. What range of output voltages can you get by covering or uncovering the photoelement?
* Connect a transistor to control the brightness of a bulb by turning the knob of a potentiometer.
* Substitute a photoresistor in place of the potentiometer.
* Light "phobic" and light "philic" circuits with a transistor
== Topics ==
* Potentiometers, photoresistors, variable resistance.
* Transistors
== Supplies ==
* TIP-120 transistor.
* Bulb.
* 10K potentiometer.
* Pliers, strippers, clippers.
* Hookup wire.
* Jumper kit (short pre-cut wires).
* Breadboard.
* Power Supply.
* Multimeter.
== Activities ==
* Explore the behavior of your potentiometer. Is the relationship between rotation + resistance linear? ("linear" vs "exponential" taper)
** What is the measure between "A" and "B"? does it change as your turn the knob?
** Record and plot the rotation of the knob and resistance at a few points. Is the relationship between them linear? ("linear" or "expontential" taper)
[[Image:Potentiometer_labelled.jpg| 300px]][[Image:Variable_resistance.png | 300px]]
* Wire up a simple voltage divider using your potentiometer and a 10K resistor, conected to the 5V supply.
** How does the output voltage vary as you turn the knob? (measure at the point between the potentiometer and the resistor)
* Photoresistor as variable resistance
** measure the "light" resistance of your photoresistor
** measure the "dark" resistance. (cover the resistor with your hand, or try shutting it in one of the lab cabinets)
** setup up a voltage divider with the photoresistor and a 10K resistor. What range of output voltages can you get by covering or uncovering the photoelement?
* Connect a transistor to control the brightness of a bulb by turning the knob of a potentiometer.
* Substitute a photoresistor in place of the potentiometer.
* Light "phobic" and light "philic" circuits with a transistor