Transcript FM Transmitter Project - Academic Csuohio

FM Transmitter Project
Dan Simon
Cleveland State University
ESC 120
Revised December 30, 2010
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Schematic Example
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Component Symbols
Wires and connections
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Component Symbols
Power sources (V) and common connections (GND)
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Component Symbols
Resistors (R) and Capacitors (C)
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Component Symbols
Diodes (D)
The arrow points in the allowed direction of
conventional (positive charges) current flow.
The bar represents the cathode, marked with
a band on most parts.
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Component Symbols
Transistors (Q)
P-channel junction
field-effect transistor
bipolar NPN
junction transistor
bipolar PNP
junction transistor
N-channel MOS
field-effect transistor
N-channel junction
field-effect transistor
P-channel MOS
field-effect transistor
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Component Symbols
Integrated circuits (U)
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Component Symbols
Switches (S) and Relays (K)
double pole single throw
DPST
single pole single throw
SPST
single pole double throw
SPDT
rotary switch
1 pole, 5 position
double pole double throw
DPDT
single pole double throw
relay
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Drawing Schematic Diagrams
Use one of the many schematic capture programs available on the
WWW for free download, for example:
ExpressPCB
EagleLite
BatchPCB
http://www.expresspcb.com/
http://www.cadsoftusa.com/freeware.htm
http://batchpcb.com
These usually include printed circuit board layout capability also.
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Building a prototype
Solderless breadboards
Perfboards or Protoboards
Etched/PrintedCircuit Boards
Cheaper but
less flexible
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Solderless Breadboards
The term breadboard originated in
the early days of radio, when many
experimenters actually built circuits
on the wooden boards used in their
mother’s kitchen for rolling out
bread dough.
Solderless breadboards: The best thing to
come along since sliced bread!
A ham radio transmitter circa 1930
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Perfbord or Protoboard
Components are soldered to the board, with connections made
using a combination of short pieces of wire and the copper traces
already present on some versions of these boards.
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Etched/Printed Circuit Boards
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Soldering
Soldering: Fastening metal objects using molten
metal (solder) as the glue.
Three requirements:
1. Low melting point metal (wire solder)
2. Heat source (soldering iron)
3. Flux (to prevent surfaces from oxidizing)
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Types of Solder
Tin-Lead solders
60% Tin, 40% Lead - solid at 361° F, liquid at 374° F
63% Tin, 37% Lead - eutectic point is 361° F
no “pasty” range so joint movement less a problem
Silver-bearing Solder
62% Tin, 36% Lead, 2% Silver - solid at 354 ° F,
liquid at 372 F
often used for surface mount components whose
contacts contain trace amounts of silver
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Soldering Irons
Constant wattage
Iron is continuously “ON” and eventually reaches
equilibrium temperature
20 to 25 watt iron sufficient for circuit board
assembly
Constant temperature
Tip incorporates a thermostatic element to
maintain desired tip temperature
650 – 750° F appropriate for circuit board
assembly
Weller® 30 watt iron
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Soldering Irons
Temperature Controlled Solder Station
Feedback control maintains tip at
desired temperature
Adjustable, often with analog or digital
temperature display
Many have grounded tip to help
prevent ESD damage
Weller® solder station
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Flux-core solder
Most solder used for electronics
assembly is in wire form, with the
flux incorporated inside the solder.
Multi-core solder has several
(usually five) separate flux channels
within the solder.
For circuit board assembly use wire
solder with a diameter of about
0.025 inch or less
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Soldering a Component
Use a lead bending jig, if available, to form the
component leads to the correct spacing
If a bending jig is not on hand, grasp the
leads, not the body, of the component with
needle-nosed pliers and bend gently.
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Soldering a Component
Insert the component’s leads through
the holes in the circuit board. The body
should lie flat against the board without
having to force it down.
Turn the board over and
gently bend the component
leads outward to hold the
component in place
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Soldering a Component
QT Movie Clip
Clean the iron tip by wiping on a damp
sponge. Tin the tip by applying solder,
then wipe again.
Apply the iron in contact with both
the circuit board pad and the
component lead. Apply solder to
the joint, not to the iron, and allow
the heated joint to melt the solder
QT Movie Clip
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Soldering a Component
Use a pair of flush-cutting wire cutters to cut off the
excess lead length as close to the board as possible.
Hold the lead so will not fly away when cut, a
possible occasion for eye injury.
!! WEAR SAFETY GLASSES !!
Inspect the soldered and
trimmed lead. It should be
uniform and shiny, with no
cracks, gaps, or graininess.
Good soldering
Bad soldering
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Soldering
• Curious Inventor tutorial: HowToSolder.flv
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FM Transmitter Project
• Electromagnetic radiation: The motion of
packets of energy called photons
• Speed = Wavelength × Frequency
• Speed of light  300 million meters/second
Wavelength is measured in meters
Frequency is measured in Hertz (sec–1)
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FM Transmitter Project
Examples:
• 100.7 FM, Wavelength = 3×108 / 100.7×106 =
2.98 meters
• 1100 AM, Wavelength = 3×108 / 1100×103 =
273 meters
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FM Transmitter Project
• Amplitude Modulation: AMDemo.mov
• Frequency Modulation: FMDemo.mov
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Resistor
Color
Codes
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Acknowledgments
LSU Aerospace Catalyst Experiences for Students project,
http://laspace.lsu.edu/aces/BalloonCourse/Electronics/Unit_Links.htm
http://hamelmer.com
http://kirkwoodschools.org/faculty/mcgeech/light%20unit
http://www.leonaudio.com.au/res-code.gif
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