Cornerstone Robotics Team Week 4



Cornerstone Electronics Technology and Robotics Week 2

Chapter 1, Science of Electricity and Electronics Continued

• Administration:

o Prayer

o Turn in quiz

o Review math pretest

• Electricity and Electronics, Section 1.3, Basic Electrical Circuit:

o A basic electrical circuit consists of three main parts:

▪ Circuit, Latin for “go around”

▪ Source of voltage (a battery, electrical outlet, solar panel, etc.)

• Battery symbol

[pic]

▪ Load, which converts electrical energy to some other form of energy such as heat, light, motion, or magnetism (a light, a bell, a motor, etc.). This is the part of a circuit that performs work.

• Lamp symbol

[pic]

• Resistor symbol

[pic]

▪ Conductors (the wires between the source and the load)

• Wire symbol are lines.

▪ A fourth part is a control device like a switch or a fuse which is not required in a circuit but they provide a safety and practical function of turning a circuit on and off.

• Switch symbol

[pic]

▪ Wire the following circuits. Have your instructor check your circuit before closing the switch.

[pic]

In Circuit 1, close the switch then disconnect any of the alligator clips and observe what happens to the lamp.

In Circuit 2, unscrew one of the lamps and observe what happens to the other lamp.

[pic]

In Circuit 3, unscrew one of the lamps and observe what happens to the other lamp.

In Circuit 4, replace the 22 ohm resistor with a 68 ohm resistor, and observe the change in the 6 V lamp.

▪ In which circuits below will the lamp(s) illuminate?

[pic]

o Three basic circuit conditions:

▪ Open circuit, a broken path therefore, no current flow.

▪ Closed circuit, an unbroken path for current from a source to a load and back to the source.

▪ Short circuit, an unwanted circuit condition where the current bypasses the load causing damage to the circuit.

▪ Demonstration of each of these conditions

o Related web sites:

▪

o Terms and definitions:

▪ Unit of Measure: A precise quantity used to state magnitudes of other quantities of the same kind (length, time, mass, etc.).

▪ NIST radio station - WWV time standard: good to within one second in more than 60 million years.

▪ NIST standard for a meter: light to travel in a vacuum in 1/299 792 458 of a second.

A measurement is a comparison to a standard. -- William Shockley

▪ Voltage (Volts, V or E): Voltage is the electromotive force or pressure that causes electrons to flow in an electrical circuit. It is measured in volts. The term electromotive force is used because electrical charge imbalance causes movement of electrons by the forces of attraction and repulsion. If we compare current to water flowing through a pipe, then voltage would be the water pressure.

• Demonstration of water analogy.

▪ Current (Amperes, I): Current is flow of electrons passing a given point. In the water analogy, current is the flow of water.

▪ Resistance (Ohms, Ω): Resistance is the opposition to flow of electrons. It is used to control the amount of voltage and/or amperage in a circuit.

▪ Conductor: Conductor is a material that has many free electrons and permits the free flow of electrons, i.e., very low resistance. Conductors will conduct electric current readily with little energy applied.

▪ Insulator: An insulator is a material with few free electrons so electrons move poorly, i.e., very high resistance. Insulators require a large amount of energy to conduct an electrical current very slightly.

• Simple demonstration of conductors and insulators.

• Further demonstrations in Week 5.

▪ Direct Current (dc): Direct current is current that flows in one direction, whether steady or in pulses. Direct current has definite polarity as in a battery. The positive terminal of a battery is labeled by the + symbol and the negative terminal is labeled by the – symbol.

▪ Alternating Current (ac): Alternating current flows in both directions. Alternating current has no fixed polarity.

• Demonstration of dc and ac on an oscilloscope.

o Steady DC

o Pulsating DC

o AC

▪ Conventional Current Flow: An old theory that states that current flows from positive to negative.

▪ Electron Flow: Electron flow states that electrons flow from negative to positive.

▪ Circuit: A complete pathway on which a current flows. A circuit is made up with components and wires.

▪ Series: A circuit where the components are connected end to end in a chainlike manner. There is only one pathway for the electricity to flow. See Circuit 2 above.

▪ Parallel: A circuit where two or more components are connected so current can flow through one component without having first to flow through another component. A circuit where there are Y’s or branching in the wiring. Another way of saying it is that a parallel circuit is one that has more than one pathway for the electricity to flow.

• See Circuit 3 above.

• ll in parallel

• The goal here is to be able to visually identify series and parallel circuits.

▪ Source of voltage and/or loads can be in series or in parallel.

• Voltage sources in series and parallel: (pg 86 & 87 E & E text).

• Batteries in series: Voltage adds and the current stays the same.

• Batteries in parallel: Voltage stays the same and the current increases.

• Electricity and Electronics, Section 3.2, Special Conductor Pathways:

o Breadboards are commonly used in experimentation or to make a prototype of a circuit before the circuit is soldered or made in mass production.

▪ Solderless breadboards:

• Connecting with holes

• 5 Position groups

• Center gap

• 25 Position distribution bus

▪ Solderless breadboard wire

▪ Solid #22 AWG hook-up wire

▪ Jumper wire

▪ Cutting, stripping, and bending wire

▪ Breadboard setup

• Power to binding posts

• SPDT switch

• Power to buses

• Power indicator LED

• Checking voltages at points

• Electricity and Electronics, Section 1.4, Ohm’s Law

o This section will be addressed in Week 3and Week 4 material.

• Robot Building for Beginners, Chapter 3, Safety

o Safety will be the number one priority for the robotics team. Hazards must be immediately reported to an adult who is attending the meeting.

o Potential dangers in robotics, (Show this list to your parents):

▪ Burns and fires during soldering and installing heat-shrink tubing.

▪ Spark or ignition sources from batteries.

▪ Possible bodily harm during drilling, cutting, filing, or milling.

▪ Chemical exposure in solder, glues, developers, etchants, and electrical components.

▪ Eye injury during drilling, cutting, soldering, stripping, and snipping.

o Instructions and labels:

▪ Read and follow the manufacturer’s instructions provided with equipment.

▪ Read Material Safety Data Sheets, (MSDS), before using or handling chemicals.

o Personal protection:

▪ Safety glasses:

• Whenever we are using tools or chemicals in the shop area, safety glasses will be required.

▪ Clothing and shoes:

• Loose clothing is not permitted in the shop area.

• Long pants are required in the shop area.

• Shoes and socks must be worn in the shop area.

• Shoes made of leather or synthetic leather are preferable.

▪ Hair:

• Long hair must be pulled and held back.

▪ Ventilation:

• Use fans to disperse harmful fumes, e.g. soldering.

o Wash before eating:

▪ After soldering, painting, sanding, or handling chemicals or metals, wash hands thoroughly with soap and water.

o Related web sites:

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