Download 4-02 IOT - The 9 Core Technologies

DRILL
April 28, 2009
Watt’s Law states that POWER equals voltage times current,
P=VI.
Solve the following problems.
Draw a schematic diagram and label all electrical components.
Show all equations, substitutions, and box in your answers with
units.
1. What is the power when 12 amperes flow through a 15 ohm
resistor?
2. What is the power when a 9 Volt battery is connected to a 0.3
ohm resistor?
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POLY ENGINEERING
Solve the following problems. Draw a schematic diagram
and label all electrical components. Show all equations,
substitutions, and box in your answers with units.
1. What is the power when 12 amperes flow through a 15
ohm resistor?
V=IR [Ohm’s Law]
12 A
15 W
V= (12 A)(15W)
V= 180 V
P=VI [Watt’s Law]
P= (180 V)(12 A)
P= 2160 Watts
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Solve the following problems. Draw a schematic diagram
and label all electrical components. Show all equations,
substitutions, and box in your answers with units.
2. What is the power when a 9 Volt battery is connected to a
0.3 ohm resistor?
V=IR
0.3 W
9V
9 V= I(0.3W)
30 A= I
P=VI
P= (9 V)(30 A)
P= 270 Watts
IOT
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POLY ENGINEERING
In the past few days, we explored Electrical and Electronic
Technologies.
We constructed electrical circuits using materials from a kit
called “Mr. Circuit”.
DID WE MEET THE MR.CIRCUIT KIT OBJECTIVES?
1. Recognize some basic components used in electronics.
2. Learn the names and schematic symbols of some
electronic components.
3. Learn to follow and understand electronic schematic
diagrams.
4. Learn the basic function of some electronic components.
5. Learn how to construct electronic devices by following
schematic diagrams.
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ELECTRICAL COMPONENT IDENTIFICATION
As a result of using the Mr. Circuit kits, students should be able
to identify the following common electrical components by
what they look like 'in-person', and by their schematic symbols.
RESISTOR
fixed value
potentiometer
CAPACITOR
ceramic
electrolytic
TRANSISTOR
n-p-n
p-n-p
DIODE
standard semiconductor diode
LED (light emitting diode)
SWITCH
push-button switch, NO
SPEAKER
SOLDERLESS BREADBOARD
9 Volt CELL
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These are the major components of the Mr. Circuit kits.
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While building the Mr. Circuit kit circuits, we learned that
some devices have a 'polarity', meaning that they have a
specific positive and negative connection, and they MUST be
connected properly in a circuit.
Some examples of devices with polarity:
LED, electrolytic capacitor, 9V battery, transistor
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PROTOTYPE CIRCUIT BOARDS (BREADBOARDS)
We used plastic prototype boards with rows and columns,
called ‘solderless breadboards’.
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The solderless breadboards had lettered columns (abcde and
fghij), and numbered rows (1 to 30).
Although we could not see them completely, there were metal
conductors within the breadboard.
Each numbered row from a-e was connected underneath and
each numbered row f-j was connected underneath.
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For example, in row 1, we found holes A1, B1, C1, D1, and E1.
They are all 'electrically connected' beneath the breadboard.
Therefore, if you inserted a wire into hole A1, and another wire
into hole E1, it was the same as if the wires were touching each
other.
However, hole J1 was not connected to A1 through E1.
F1, G1, H1, I1, and J1 are connected to each other.
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We learned that there are two categories of resistors:
1. Fixed value resistors - these resistors have one designed
value of resistance, although that value can change due
to other factors, such as temperature changes.
2. Variable value resistors - these resistors are designed so
that the resistance can be changed. They are sometimes
called potentiometers or rheostats. An example is found
in a 'dimmer' switch, or the 'volume' control on a radio.
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On our first day of electrical/electronic project work using the
Mr. Circuit kits, we learned how a fixed value resistor works
and how a potentiometer works.
Fixed value resistors utilize the ‘resistor color code’.
This code assigns a number to a standard color.
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The resistor directly below with Orange-Black-Orange
represents 30 times 1,000 which is equal to 30,000 ohms.
Another way to arrive at the same answer is 30 plus 3 zeros,
which is equal to 30,000 ohms.
The gold stripe represents a tolerance of +/- 5%.
What is the value of
the resistor above?
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The resistor on the previous slide has a color code of
yellow-violet-orange-gold which translates to 4-7 plus 3 zeros,
or 47000 ohms +/- 5%.
Potentiometer
schematic symbol
Fixed value resistor
schematic symbol
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Our first project with the Mr. Circuit kits involved 3 different
resistance values connected to a red LED bulb. When the
resistance was increased, the current decreased and the LED
bulb was dimmer. Next, we connected a potentiometer to the
LED bulb, which functioned as an adjustable dimmer switch.
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Our second project with the Mr. Circuit kits introduced the
photocell (actually photoresistor) and the transistor.
The photocell has a resistance which changes depending on
how much light shines on it. The transistor is a device that can
amplify a weak electrical current.
The first circuit involved an LED which grew dimmer when we
blocked the light from reaching the photocell.
The second circuit involved a pair of LEDs which lit up only
when the photocell was in the dark. This was the automatic
night light circuit.
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Our third project with the Mr. Circuit kits introduced the
electrolytic capacitor, ceramic capacitor, and the NE555
integrated circuit (IC).
The capacitor is a device that can store electricity. The NE555 is
a device that incorporates many other components into one
‘integrated’ package and is used in timing circuits.
The first circuit with an electolytic capacitor involved an LED
which did not go out immediately when the battery was
removed, but grew dimmer as the capacitor ‘discharged’.
The second circuit involved a pair of LEDs which lit up
alternately. This was the variable speed lights circuit.4-02
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As mentioned on the previous slide, the NE555 is a device that
incorporates many other components into one ‘integrated’
package and is used in timing circuits.
To satisfy your curiosity, here is the internal schematic of the
NE555 showing that there are 24 transistors and 16 resistors:
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Our fourth project with the Mr. Circuit kits introduced the
speaker and pushbutton switch (NO) and used many of the
other components from the previous three days.
The speaker is a device that produces sound when electric
current flows through it. Like an electric motor (which you
studied last year in FOT), the speaker uses magnets and wire.
The pushbutton switch (NO) is normally open, meaning that
current does not flow unless we push on the button.
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The circuit we built with the speaker was a code oscillator
circuit. With this circuit, we could create sounds similar to
Morse Code. By sheer coincidence, we built this circuit on
Samuel F. B. Morse’s 218th birthday, April 27!!
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