Transcript Transistor

Transistor
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Transistor
• Transistors are used to turn components on
and off
• They come in all different shapes and sizes
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Purpose
• To turn components on and off we could use the Arduino
digital pins
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Purpose
• To turn components on and off we could use the Arduino
digital pins
• However, they only output 5V and 20mA, about enough
to light up an LED
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How it works
12V
• Suppose we wanted to operate the LED
on the left, with its switch and 12V supply
12V
• But instead of a manual switch, we can
have an Arduino “flip” a transistor
• In the diagram on the right a transistor
has replaced the switch
• By sending a small
amount of current
through A, we allow a
large amount to flow
from B to C
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Wiring
• We can trace the
circuit for the DC
motor on the right
• A – power into red bar
• B – into the motor
• C – out of the motor
• D – into the transistor
• E – out of the transistor
• F – back into ground
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Wiring
• Note how the
transistor is an integral
part of the circuit
• It is acting as the
switch
• The third leg is called
the “gate”, and is used
to “operate the switch”
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Wiring
• Connect the gate to an
Arduino pin
• digitalWrite HIGH
= ON
• digitalWrite LOW
= OFF
• A pull down resistor
connected to ground is
needed to turn the
switch off when the
Arduino pin is LOW
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LAB
Complete the Transistor lab in
Unit 11 of your textbook
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