POTENTIOMETER
I.
Introduction
Potentiometer is
known to be an example of a resistor which generally comes in variable.
Meaning, its resistance is adjustable with the help of an adjusting knob.
Potentiometer is also commonly called “pot” in short. This chapter will give
you an idea of what is a potentiometer, its composition and types and its
application to the world of electronics.
II.
Parts
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III.
Types
A. According to Composition
Common
materials that are used to construct potentiometers include
1. Carbon – commonly used type with the composition
of carbon in an insulating wafer.
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2. Cermet – preferably to use in high temperature
because of its ceramic and metallic composite.
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3. Wirewound- coils of wire are being wounded
used in high power connection.
4. Conductive plastic or metal film – special
plastic material is used and known to be its excellent performance and high
quality.
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B. According to Varying Resistance
1. Adjustable
– common type where the manipulation is done in the potentiometer itself.
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2. Preset – from the
name itself it means that the manipulation is set before connecting in a
circuit.
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3. Digital – the variation of resistance is though electronic input.
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C. According to the Track of Manipulating
1. Linear. The manner of manipulating is through sliding in a linear way.
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2. Rotary. The manner of manipulating is through rotating the knob. Example for this is the volume knob of our radio.
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IV. Applications
If we account all the applications of a potentiometer, it will be difficult. But we will have the common application of it that is much known to us.
1. Audio control. This refers to the control of the sound. Behind the volume knob of our audio devices is the presence of potentiometer.
2. Light control. This also refers to the control of light brightness. Example form this is the dimmer used in some homes.
V. Potentiometer
symbols
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Reference:
1. Variable Resistors. Retrieved on August 31, 2015 from http://www.electronics-radio.com/articles/electronic_components/resistors/variable-resistors-potentiometers.php
Laboratory
Experiment
Potentiometer
I.
Objectives: This laboratory experiment aims to
a. Use potentiometer in a circuit
b. Manipulate the potentiometer in different voltages
c. Give particular applications of potentiomter
II.
Materials:
· AC-DC converter
· Alligator clips
· Bulb
· Potentiometer
· Resistor (1100 Ω)
· Multitester
III.
Procedures:
1. Record the resistance of the bulb and the resistor.
2. Set up a circuit having a bulb and potentiometer in a series.
3. Gradually increase the voltage source for atleast five times.
4. Get the actual voltage output.
5. Manipulate the potentiometer by rotating its knob in every increase of voltage output.
6. Obtain Vdrops when the potentiometer is closed, half-opened and opened.
7. Observe the brightness of the bulb when potentiometer is manipulated.
8. Provide table for your data.
9. Insert a resistor in the set-up.
10. Repeat procedures from 1-7.
11. Record data on another table.
IV.
Data
and Results:
VOLTAGEOUT (V)
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VOLTAGEDROP (v)
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CLOSED POT
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HALF-OPENED POT
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OPENED POT
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3.1
V
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2.8
V
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1.4
V
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0V
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5.2
V
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4.6
V
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2.2
V
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0V
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7.2V
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6.8
V
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3.5
V
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0V
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9.2V
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9.0
V
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4.3
V
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0V
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12V
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10
V
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4.8
V
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0V
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BRIGHTNESSBULB
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BRIGHT
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DIM
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NO LIGHT
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Observations: I observed that the voltage drops as well as the light of the bulb are affected as the potentiometer is opened.
Table B: POT with FIXED RESISTOR R= 1100 Ω RBULB= 20 Ω
VOLTAGEOUT (V)
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VOLTAGEDROP (v)
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CLOSED POT
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HALF-OPENED POT
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OPENED POT
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3.2
V
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2.2
V
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1.1
V
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0
V
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5.2
V
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3.9
V
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1.8
V
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0
V
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7.4
V
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5.8
V
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2.7
V
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0
V
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9.4
V
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7.6
V
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3.8
V
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0
V
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12V
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8
V
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4.2
V
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0
V
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BRIGHTNESSBULB
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BRIGHT
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DIM
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NO LIGHT
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Observations: Same thing happened with the first set-up. The Vdrops decreased until became zero.
Based on the data, it is can be concluded that potentiometer really affects the current with its resistance value that can be manipulated. As the potentiometer is totally opened, current is zero causing to have no light in the bulb.
V. Post-laboratory Questions:
1. What happened to the Vdrops as the potentiometer was gradually opened?
As the potentiometer was gradually increased, the Vdrops were decreasing until it became zero.
2. How will you describe the light of the bulb? What is the implication of the decreasing intensity of the bulb as the potentiometer was gradually opened?
The light of the bulb was getting dimmer as the potentiometer was gradually opened. The decreasing light of the bulb implies the decreasing current also in the circuit.
3. How is potentiometer used in appliances and devices?
Potentiometer is used as a variable resistor that can be adjusted from time to time. The variation of potentiometer is the control of brightness and volume in devices like phones and others.
VI. Generalization:
Based on the data, it is can be concluded that potentiometer really affects the current with its resistance value that can be manipulated. As the potentiometer is totally opened, current is zero causing to have no light in the bulb.
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