EEEElectrical Engineering Excitement

Saturday, December 7, 13

If you wish to make an apple pie from scratch, you must first

invent the universe.Carl Sagan (Cosmos p218)

Saturday, December 7, 13

If you wish to make a robot from scratch, you must first learn some basic electrical theory.

Not Carl Sagan (Cosmos p218)

Saturday, December 7, 13

What this gets you• LEDs

• Lasers

• Servos

• Motors

• Touch Sensors

• Switches

• Light Sensors

• Joysticks

• LCD Displays

• Accelerometers

• Radios

• oh so much more

Saturday, December 7, 13

ELECTRONS

Saturday, December 7, 13

ELECTRONS

e-

e-

e-

e-

e-

• Negatively Charged

• Like to be evenly spaced

• Flow from negative areas to positive areas

- +

Saturday, December 7, 13

ELECTRONS

e-

e-

e-

e-

e-• The flow of electrons is the

basis of electricity

• Current = Electrons per second (measured in Amps)

• Voltage = difference between the positive and negative charges (measured in Volts)

- +

Saturday, December 7, 13

ELECTRONSe-

• The the larger the difference between negative and positive charges the faster the electrons will flow.

• More voltage leads to more amperage

- +

Saturday, December 7, 13

ELECTRONSe-

• The the larger the difference between negative and positive charges the faster the electrons will flow.

• More voltage leads to more amperage

- +

Saturday, December 7, 13

ELECTRONSe-

• The the larger the difference between negative and positive charges the faster the electrons will flow.

• More voltage leads to more amperage

- +

Meow!

Saturday, December 7, 13

Voltage Terms• VCC

• Vin

• +5v

• Vout

• GND (Ground)

• 0v

• -5v

• -

Saturday, December 7, 13

Conductors

Saturday, December 7, 13

• Electrons flow over a Conductor

• Some conductors pass electrons better than others. You measure this ability in units of resistance.

• Copper wire is the commonly used conductor today

• Humans will are less commonly used

Conductors

Saturday, December 7, 13

• All Conductors have some resistance

• The unit of electrical resistance is the ohm Ω

• Comparable to friction

• Resistors can be useful to slow down the electrons

Resistors

Saturday, December 7, 13

Ohms Law

V=IR

Voltage = Current * ResistanceResistance = Voltage / CurrentCurrent = Voltage / Resistance

Saturday, December 7, 13

Resistor Symbols

Resistor Rheostat Potentiometer

Saturday, December 7, 13

Voltage Symbols

Saturday, December 7, 13

Diagrams

1. +5V (Red)2. −Data (White)3. +Data (Green)4. GND (Black)

Saturday, December 7, 13

Diagrams

• Symbols rule

• US Style, IEC style, stuff people make up style

• Know the terms

• Identify the electron flow

Saturday, December 7, 13

LEDs

Saturday, December 7, 13

LEDs• Silicon Voltage Drop (1.2v)

• Adjust current for brightness

• Max Current listed in docs. Often 10-20mA

• Needs a resistor for protection

• R = V / I

• (5v - 1.2v) / 0.02A = 190 Ω

Saturday, December 7, 13

Diagrams

What’s going on here?

Saturday, December 7, 13

SERVOS

Saturday, December 7, 13

SERVOS

• Black GND

• RED +5v

• Yellow PWM Signal

Saturday, December 7, 13

What’s PWM?• Pulse Width Modulation

• Voltage switches between 0v and Vin

• % of time the voltage is at Vin is the duty cycle

• Servos understand this to be % of angle I should turn

• LEDS brightness is affected

Saturday, December 7, 13

What’s TTL?

• It’s how most digital logic communicates

• It encodes 0s and 1s into +5v and 0v

• or +3v and 0v

• Some devices work on both voltages

• Some break with the wrong voltage

Saturday, December 7, 13

DIP Chips

• Dual Inline Pin

• Pins are Numbered Counter Clockwise

• “Bite” of the Chip is at the top

• The “Pin Out” or “data sheet” tells you what each pin does

Saturday, December 7, 13

555 Timer

Saturday, December 7, 13

DATA SHEETSRead Them

Saturday, December 7, 13

What did we learn?

• Electron Flow

• Voltage = Current * Resistance

• How to Read Diagrams

• How LEDs, Servo’s and DIP Chips work

• PWM & TTL

Saturday, December 7, 13

Image Credits• https://en.wikipedia.org/wiki/

Crook%27s_Tube

• http://www.adafruit.com/products/758

• https://en.wikipedia.org/wiki/Copper_wire_and_cable#Solid_vs._stranded

• http://learn.adafruit.com/

• http://www.rapidtables.com/electric/electrical_symbols.htm

• http://en.wikipedia.org/wiki/LED

• http://mcuoneclipse.com/2013/05/30/tutorial-arduino-motorstepperservo-shield-part-1-servos/

• http://biorob.epfl.ch/cheetah

• http://electronicsclub.info/circuitsymbols.htm

Saturday, December 7, 13

INSTRUCTABOTS.COMSHARE YOUR ROBOT’S CODE, PARTS AND STORY

Saturday, December 7, 13

INSTRUCTABOTS.COMSHARE YOUR ROBOT’S CODE, PARTS AND STORY

Meow!

Saturday, December 7, 13

Francis Gulotta

@reconbot github.com/reconbotrbrtr.com wizarddevelopment.com

Saturday, December 7, 13