Learning about Electrical
Components
ES 110
Basic Components
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Function generator
LED
Relay
Speaker
Pot
Ohm’s Law
Drawing the circuit
Schematic capture:
http://phet.colorado.edu/simulations/sims.php?sim=
Circuit_Construction_Kit_ACDC
Relay
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A relay is an electrically operated switch.
Many relays use an electromagnet to operate a
switching mechanism mechanically, but other
operating principles are also used.
Different Types of Relays
An SPST relay (Single Pole Single Throw)
simply opens or closes a signal path. This relay
is typically normally open when power is
removed, and the relay needs to be energized in
order to connect the signal path.
A DPST relay (Double pole Single Throw) is in
essence two SPST relays but energized from
the same coil.
A SPDT (Single Pole Double Throw) relay has
one normally open and one normally closed
path and a DPDT (Double Pole Double Throw)
relay is in essence two SPDT relays which are
energized from the same coil.
Part I:
Connecting a Relay
1. What is the minimum
voltage required to turn
on the relay?
Part 2: Photoresistor
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A photoresistor is a sensor whose resistance varies with light intensity. Most
decrease in resistance as the light intensity increases.
Light
Condition
Resistance
Completely
Dark
A little Dark!
Room
Condition
Flash Light
Fixed
Resistance
V(Out)
Input Voltage (5V)
Part 2: Photoresistor
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Using Excel plot Voltage vs. Resistance of the photo resistor. Is it linear?
Using MSWord draw your circuit (as shown below)
Include the table in your report
What are the potential applications of a photoresistor?
Redraw the following circuit and explain what it does.
Part 3: Make the following
measurements:
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Adjust the generator so you see a 2V peak-to-peak square wave signal with
frequency of 8.5 KHz. DON’T forget UNITS!
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Take a snapshot of the signal (your snapshot must contain at least 2 cycles of the
signal)- Use the figure in the previous slide.
On you snapshot indicate how you measure Vpp, DC voltage (also called the offset),
and the period (as shown the previous slide). Watch the video for more information.
Use MSWord Equations to calculate the frequency of the signal from your plot. Show
all your work.
What is Vp of this signal?
Take another snapshot of the signal. This time make sure you set the voltage cursers
to show the Vpp.
Part 4: Connect Photo Resistor to
the Relay and Turn on the Siren!
GND
1
5V