Transcript "Electrobot" Project

Computer Hardware Technology
ELECTROBOT PROJECT
Computer Technology: ELECTROBOT
• Task: Teams of 2 will design and build an electronic
control system for a 4 LED display mask. The
controller will then be used to guide a team member
wearing the mask through a maze. The goal is to pick
up an object in the least amount of time.
• Requirements:
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Project report: description, diagram and parts list
Safety notes
Build mask and controller, following tool procedures
Complete a timed race through the maze
Finding the Value of a Resistor by Color
Codes
• Step One: Turn the resistor so that the gold or silver
stripe is at the right end of the resistor.
• Step Two: Look at the color of the first two stripes on
the left end. These correspond to the first two digits
of the resistor value. Use the colour table given to
determine the first two digits.
• Step Three: Look at the third stripe from the left. This
corresponds to the multiplier (# of 0’s to add).
Practice this with real resistors!
Electricity Theory – Pressure & Flow
Basic Measures of Electricity
• V- electrical pressure measured in volts (V)
• I - current flow measured in amperes (A)
• R- resistance measured in ohms (symbol Ω)
Ohm's Law: V = I x R
if you know any 2 values in a circuit you can
calculate the other value
* Note - Another important measure is Power: P= I x V (in watts)
Resistors
• Used to control current
(I) or voltage (V)
• maximum power level
measured in watts (V x
I) depends on material
inside & physical size
• resistance value in
units of OHMS based
on colour coded
stripes for small
resistors
• BBROYGBGW…
Resistor Colour Coding
Number
Colour
0
black
1
brown
2
red
3
orange
4
yellow
5
green
6
blue
7
violet
8
grey
9
white
• Colour bands are assigned number
values to determine the ohm
value…
LED – Light Emitting Diode
• LED uses V = 2 volts
• Works best at I = 10- 20mA
• Must use a resistor R to
limit the current or it will
burn out.
• Calculate R needed if Vsupply
= 9 volts (ohm’s law)
– R = (V Supply - VLED) / I
+
-
symbol
– current only flows from + to - lead
Parts & Schematic Diagram
Controller
Parts:
• 4 LEDs
• 470 ohm resistor
• Copper tape
• 5 wires
• 9 volt battery
• Battery terminal
• Cardboard
9 volts
DC
R = 470 ohms
Mask
Tools – Use properly and safely*
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Soldering iron
Safety glasses
Exhaust fan
Wire strippers – follow the demo
Wire cutters
Scissors
Digital Multimeter (DMM)
* Zero tolerance for misuse or horse play with tools
and equipment
Soldering
Soldering is the process of joining two metals
together using a low temperature melting alloy.
http://www.curiousinventor.com/guides/How_To_Solder
http://store.curiousinventor.com/guides/how_to_solder/heat_solder
http://www.sentryair.com/solder%20fume.htm
Instructor will assess solder safety and quality
Good solder joints: smooth, shiny, and filled in a concave fashion
Poor solder joints: dull, irregular shape and/or pooled in a blob
Soldering
Safety Hazards
BURNS – Soldering iron tip is very hot (~350
degrees Celsius)
FUMES – Melting metal and flux produces fumes
that irritate the respiratory and digestive
system
SPLASH – Hot solder splashes or rosin flux
POISON – Lead is poisonous, and flux can be
corrosive to skin
TAKE STRICT PRECAUTIONS ---- > next page
Soldering Safety Precautions
1.
2.
3.
4.
5.
6.
Wear safety glasses
Keep work areas neat and well spaced
Hot soldering irons - move slowly
Keep electrical cords away from iron & stand
Fumes - work in a well ventilated area
Do not hold parts to be soldered – use clips,
pliers, and other holding tools
7. No food in the area
8. Hand washing after exposure to solder
9. Zero tolerance for misuse or horse play.
Building the Electrobot
1. Prepare five wires of 4’ length & bundle them
– Strip 1” of insulation off both ends
2. Cut out a controller from cardboard (4” x 4”)
– Fold and trim 4 switches
– Place copper tape in position
– Secure finished wire bundle with masking tape
3. Cut out a LED display of cardboard (3” x 3”)
– Mark the + and - positions for 4 LEDs
– Make pin holes for LED leads and insert them
– Wrap on 1 wire to each +, then 5th wire to 4 – leads
4. Begin soldering, following correct procedures
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Safety glasses, fans, holding tools correctly
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Preparation
Soldering Technique
1. Use safety glasses and exhaust fan – don’t inhale any fumes
2. Place a wet sponge on the stand – clean the tip frequently
3. Place a mat down to protect the work surface
4. Electrical cord runs from front-right or left (depending on hand used)
5. Parts to be soldered must be clean
6. Soldering iron tip should be clean
7. Securely position the components to be soldered, it should not move
• Application : Solder the 4” x 4” control board that has been preparedred
1. Apply heat at the joint
2. Apply solder on the other side of the joint (not on the iron)
3. Solder will flow once the joint is heated enough
4. Do NOT let solder flow for more than 1-2 seconds
5. Remove solder wire, and then remove the hot iron
6. The solder will harden very quickly