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**Technician License Class**

Chapter 3 Electricity, Components and Circuits

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**Electricity Voltage and Current**

Current is the flow of electrons through a material. The magnitude of a current is the number of electrons flowing past a given point in one second Measured in amperes 1 Amp = 1 coulomb/second 1 coulomb ≈ 6.24 billion billion (6.24 x 1018) electrons Abbreviated to ”Amp” or “A” Use symbol “I” in formulas Current is measured using an ammeter.

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**Electricity Voltage and Current**

Voltage is the electrical force that causes electrons to flow. a.k.a. – Electromotive force (EMF), potential. Measured in volts. Abbreviated to “V” Use symbol “E” in formulas Voltage is measured using a voltmeter.

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**Electricity Voltage and Current Voltage has polarity.**

Positive voltage attracts electrons. Negative voltage repels electrons. Voltage is always referenced between 2 points. Surface of the earth is often used as a universal reference point. Called earth ground, ground potential, or ground.

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**Volts Watts Ohms Amperes**

T5A01 -- Electrical current is measured in which of the following units? Volts Watts Ohms Amperes

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**Voltage Resistance Capacitance Current**

T5A03 -- What is the name for the flow of electrons in an electric circuit? Voltage Resistance Capacitance Current

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**Voltage Ampere-hours Capacitance Inductance**

T5A05 -- What is the electrical term for the electromotive force (EMF) that causes electron flow? Voltage Ampere-hours Capacitance Inductance

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**T5A11 -- What is the basic unit of electromotive force?**

The volt The watt The ampere The ohm

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**Electricity Resistance All materials resist the flow of electrons.**

Materials with very little resistance are called conductors. Materials with a lot of resistance are called insulators. Resistance is measured in ohms. Symbol is Greek letter Omega (Ω). Use “R” in formulas. Measured with an ohmmeter.

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**T5A07 -- Which of the following is a good electrical conductor?**

Glass Wood Copper Rubber

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**T5A08 -- Which of the following is a good electrical insulator?**

Copper Glass Aluminum Mercury

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**T7D05 -- What instrument is used to measure resistance?**

An oscilloscope A spectrum analyzer A noise bridge An ohmmeter

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Electricity Ohm’s Law First published in 1827 by Georg Ohm in his book “Die galvanische Kette, mathematisch bearbeitet ” Mathematically describes the relationship between voltage, current, and resistance. Most basic formula in electricity and electronics.

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**Electricity Ohm’s Law R = Resistance E = I x R I = E/R R = E/I**

E = Electromotive Force Force causing electrons to flow. I = Current Intensity Number of electrons flowing past a point in a given period of time. R = Resistance Opposition to flow of electrons. E = I x R I = E/R R = E/I

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**Electricity Voltage and Current**

The flow of water through a hose is a good analogy to understand the characteristics of electricity and how they are related.

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**T5D01 -- What formula is used to calculate current in a circuit?**

Current (I) equals voltage (E) multiplied by resistance (R) Current (I) equals voltage (E) divided by resistance (R) Current (I) equals voltage (E) added to resistance (R) Current (I) equals voltage (E) minus resistance (R)

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**T5D02 -- What formula is used to calculate voltage in a circuit?**

Voltage (E) equals current (I) multiplied by resistance (R) Voltage (E) equals current (I) divided by resistance (R) Voltage (E) equals current (I) added to resistance (R) Voltage (E) equals current (I) minus resistance ®

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**T5D03 -- What formula is used to calculate resistance in a circuit?**

Resistance (R) equals voltage (E) multiplied by current (I) Resistance (R) equals voltage (E) divided by current (I) Resistance (R) equals voltage (E) added to current (I) Resistance (R) equals voltage (E) minus current (I)

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T5D04 -- What is the resistance of a circuit in which a current of 3 amperes flows through a resistor connected to 90 volts? 3 ohms 30 ohms 93 ohms 270 ohms

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T5D05 -- What is the resistance in a circuit for which the applied voltage is 12 volts and the current flow is 1.5 amperes? 18 ohms 0.125 ohms 8 ohms 13.5 ohms

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**T5D06 -- What is the resistance of a circuit that draws 4 amperes from a 12-volt source?**

3 ohms 16 ohms 48 ohms 8 Ohms

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**9600 amperes 200 amperes 0.667 amperes 1.5 amperes**

T5D07 -- What is the current flow in a circuit with an applied voltage of 120 volts and a resistance of 80 ohms? 9600 amperes 200 amperes 0.667 amperes 1.5 amperes

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**20,000 amperes 0.5 amperes 2 amperes 100 amperes**

T5D08 -- What is the current flowing through a 100-ohm resistor connected across 200 volts? 20,000 amperes 0.5 amperes 2 amperes 100 amperes

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**24,000 amperes 0.1 amperes 10 amperes 216 amperes**

T5D09 -- What is the current flowing through a 24-ohm resistor connected across 240 volts? 24,000 amperes 0.1 amperes 10 amperes 216 amperes

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**T5D10 -- What is the voltage across a 2-ohm resistor if a current of 0**

T5D10 -- What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it? 1 volt 0.25 volts 2.5 volts 1.5 volts

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**T5D11 -- What is the voltage across a 10-ohm resistor if a current of 1 ampere flows through it?**

10 volts 11 volts 9 volts

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**8 volts 0.2 volts 12 volts 20 volts**

T5D12 -- What is the voltage across a 10-ohm resistor if a current of 2 amperes flows through it? 8 volts 0.2 volts 12 volts 20 volts

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**Electricity Circuits A circuit is any path where current can flow.**

For current to flow, the circuit must be closed. Current eventually ends up back where it started. If only one path, it is a series circuit. If multiple paths, it is a parallel circuit.

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Electricity Circuits Series circuit

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Electricity Circuits Parallel circuit

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**Electricity Circuits Measuring voltage and current**

Voltmeters are always placed in parallel with the circuit. Ammeters are always placed in series with the circuit

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**An ammeter A voltmeter A wavemeter An ohmmeter**

T7D01 -- Which instrument would you use to measure electric potential or electromotive force? An ammeter A voltmeter A wavemeter An ohmmeter

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**T7D02 -- What is the correct way to connect a voltmeter to a circuit?**

In series with the circuit In parallel with the circuit In quadrature with the circuit In phase with the circuit

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**T7D03 -- How is an ammeter usually connected to a circuit?**

In series with the circuit In parallel with the circuit In quadrature with the circuit In phase with the circuit

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**T7D04 -- Which instrument is used to measure electric current?**

An ohmmeter A wavemeter A voltmeter An ammeter

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**Electricity The Multimeter The most basic piece of test equipment.**

Everybody should have one. Three (or more) instruments in one: Voltmeter Ammeter Ohmmeter Measures volts, amperes, and ohms in one package.

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**Electricity The Multimeter Digital multimeter (DVM) Very inexpensive.**

Often has extra features in addition to measuring volts, amps, & ohms.

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**Electricity The Multimeter Meters can only measure current.**

A voltmeter measures voltage by: Placing a known resistance in series with the voltage being measured. Measuring the resulting current. Calculating the voltage using Ohm’s law. An ohmmeter measures resistance by: Applying a known voltage to the circuit being measured. Calculating the resistance using Ohm’s law.

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**Electricity The Multimeter Measuring resistance.**

NEVER attempt to measure resistance with power applied to the circuit. You WILL damage your multimeter. NEVER attempt to measure voltage with the resistance setting.

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**Electricity The Multimeter**

If a resistance reading is initially very low but slowly increases to a higher value, it indicates the presence of a large capacitance in the circuit.

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**T7D06 -- Which of the following might damage a multimeter?**

Measuring a voltage too small for the chosen scale Leaving the meter in the milliamps position overnight Attempting to measure voltage when using the resistance setting Not allowing it to warm up properly

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**Signal strength and noise Impedance and reactance **

T7D07 -- Which of the following measurements are commonly made using a multimeter? SWR and RF power Signal strength and noise Impedance and reactance Voltage and resistance

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**The ohmmeter is defective The circuit contains a large capacitor **

T7D10 -- What is probably happening when an ohmmeter, connected across an unpowered circuit, initially indicates a low resistance and then shows increasing resistance with time? The ohmmeter is defective The circuit contains a large capacitor The circuit contains a large inductor The circuit is a relaxation oscillator

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**Ensure that the applied voltages are correct **

T7D11 -- Which of the following precautions should be taken when measuring circuit resistance with an ohmmeter? Ensure that the applied voltages are correct Ensure that the circuit is not powered Ensure that the circuit is grounded Ensure that the circuit is operating at the correct frequency

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**Ensure that the voltmeter has very low impedance **

T7D12 -- Which of the following precautions should be taken when measuring high voltages with a voltmeter? Ensure that the voltmeter has very low impedance Ensure that the voltmeter and leads are rated for use at the voltages to be measured Ensure that the circuit is grounded through the voltmeter Ensure that the voltmeter is set to the correct frequency

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**Electricity Power The rate at which energy is consumed.**

Measured in watts Abbreviated “W” Use symbol “P” in formulas Power is measured using a wattmeter.

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**Electricity P E I P = E x I E = P / I I = P / E P = E2/R P = I2 x R**

Power P = E x I E = P / I I = P / E P = E2/R P = I2 x R P Watts E I Volts Amps P = Power E = Voltage I = Current

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Electricity AC and DC When current flows in only one direction, it is called direct current (DC). Batteries are a common source of DC. Most electronic devices are powered by DC. When current flows alternatively in one direction then in the opposite direction, it is called alternating current (AC). Rate at which direction changes is called the frequency. Your household current is AC.

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**T5A02 -- Electrical power is measured in which of the following units?**

Volts Watts Ohms Amperes

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**Alternating current Direct current Normal current Smooth current**

T5A04 -- What is the name for a current that flows only in one direction? Alternating current Direct current Normal current Smooth current

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**Alternating current Direct current Circular current Vertical current**

T5A09 -- What is the name for a current that reverses direction on a regular basis? Alternating current Direct current Circular current Vertical current

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**Resistance Current Power Voltage**

T5A10 -- Which term describes the rate at which electrical energy is used? Resistance Current Power Voltage

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**Power (P) equals voltage (E) multiplied by current (I) **

T5C08 -- What is the formula used to calculate electrical power in a DC circuit? Power (P) equals voltage (E) multiplied by current (I) Power (P) equals voltage (E) divided by current (I) Power (P) equals voltage (E) minus current (I) Power (P) equals voltage (E) plus current (I)

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**138 watts 0.7 watts 23.8 watts 3.8 watts**

T5C09 -- How much power is being used in a circuit when the applied voltage is 13.8 volts DC and the current is 10 amperes? 138 watts 0.7 watts 23.8 watts 3.8 watts

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**4.8 watts 30 watts 14.5 watts 0.208 watts**

T5C10 -- How much power is being used in a circuit when the applied voltage is 12 volts DC and the current is 2.5 amperes? 4.8 watts 30 watts 14.5 watts 0.208 watts

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**0.1 amperes 10 amperes 12 amperes 132 amperes**

T5C11 -- How many amperes are flowing in a circuit when the applied voltage is 12 volts DC and the load is 120 watts? 0.1 amperes 10 amperes 12 amperes 132 amperes

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**Components Basic Components There are 3 basic types of components:**

Resistor Unit of measurement of resistance is the ohm (Ω). Capacitor Unit of measurement of capacitance is the farad (F). Inductor Unit of measurement of inductance is the henry (H).

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**Components Basic Components Resistors**

The function of the resistor is to oppose the flow of electric current. Dissipates energy as heat. Potentiometer. Volume control.

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**Components Basic Components Resistors.**

A fixed amount of a partially conductive material. Ratings. Resistance. Ohms (Ω), kilohms (kΩ), megohms (MΩ) Values from <1 Ω to >10 MΩ. Maximum power in watts (W). Values from a fraction of a watt to a couple to >100 W.

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**Components Basic Components Capacitors.**

The function of the capacitor is to temporarily store electrical energy. Stores energy in an electric field. Like a very temporary storage battery.

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**Components Basic Components Capacitors.**

Two conductive surfaces separated by an insulator. Ratings. Capacitance in picofarads (pF), microfarads (μF), or farads (F). Values from 1 pF to 1 F. Maximum voltage in volts (V), or kilovolts (kV). Values from a few volts to several kilovolts.

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**Components Basic Components Inductors.**

The function of the inductor is to temporarily store electrical energy. Basically a coil of wire. Stores energy in a magnetic field.

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**Components Basic Components Inductors.**

A coil of wire wound around a non-magnetic form or a magnetic core. Ratings. Inductance in microhenries (μH), millihenries (mH), or henries (H). A few microhenries to several henries. Maximum current in milliamperes (mA) or amperes (A). A few milliamperes to several amperes.

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**Components Basic Components Transformers.**

Two or more inductors arranged so that they share their stored magnetic energy. Used to change AC voltage levels. e.g. - Change 120 VAC household voltage to a lower value for use in electronic equipment.

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Components Color Code. Component values often marked on component by colored stripes or dots. Very common with resistors. Less common with capacitors and inductors. Axial-lead cases.

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Components Color Code.

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Components Color Code. Bad Boys Rape Our Young Girls But Violet Gives Willingly. Bad Boys Rape Our Young Girls Behind Victory Garden Walls. Bad Beer Rots Out Your Guts But Veggies Go Well. Get Some Now (tolerance)

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**Inductance Resistance Tolerance Capacitance**

T5C01 -- What is the ability to store energy in an electric field called? Inductance Resistance Tolerance Capacitance

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**T5C02 -- What is the basic unit of capacitance?**

The farad The ohm The volt The henry

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**Admittance Capacitance Resistance Inductance**

T5C03 -- What is the ability to store energy in a magnetic field called? Admittance Capacitance Resistance Inductance

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**T5C04 -- What is the basic unit of inductance?**

The coulomb The farad The henry The ohm

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**Inductor Resistor Voltmeter Transformer**

T6A01 -- What electrical component is used to oppose the flow of current in a DC circuit? Inductor Resistor Voltmeter Transformer

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**Fixed resistor Power resistor Potentiometer Transformer**

T6A02 -- What type of component is often used as an adjustable volume control? Fixed resistor Power resistor Potentiometer Transformer

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**T6A03 -- What electrical parameter is controlled by a potentiometer?**

Inductance Resistance Capacitance Field strength

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**T6A04 -- What electrical component stores energy in an electric field?**

Resistor Capacitor Inductor Diode

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**Resistor Potentiometer Oscillator Capacitor**

T6A05 -- What type of electrical component consists of two or more conductive surfaces separated by an insulator? Resistor Potentiometer Oscillator Capacitor

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**Resistor Capacitor Inductor Diode**

T6A06 -- What type of electrical component stores energy in a magnetic field? Resistor Capacitor Inductor Diode

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**Switch Capacitor Diode Inductor**

T6A07 -- What electrical component is usually composed of a coil of wire? Switch Capacitor Diode Inductor

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**Variable capacitor Transformer Transistor Diode**

T6D06 -- What component is commonly used to change 120V AC house current to a lower AC voltage for other uses? Variable capacitor Transformer Transistor Diode

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**Components Reactance and Impedance.**

In circuits containing only resistors, voltage & current are always “in phase”. Current flow changes at the same time and in the same direction as the voltage change. A special kind of resistance to the flow of AC is called reactance (X). Reactance also measured in Ohms (Ω).

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**Components Reactance and Impedance.**

In circuits containing capacitors or inductors, voltage & current are “out of phase”. Current flow changes before the voltage changes in a capacitor. Current “leads” voltage. Current flow changes after the voltage changes in an inductor. Current “lags” voltage.

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**Components Reactance and Impedance.**

Opposition to AC current flow in capacitors or inductors is called reactance (X). Reactance (R) is measured in Ohms (Ω). Capacitive reactance (XC) is measured in Ohms (Ω). Inductive reactance (XL) is measured in Ohms (Ω). Combination of resistance and reactance is called impedance (Z). Impedance (Z) is measured in Ohms (Ω).

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Components Resonance. Because current leads voltage in a capacitor & lags voltage in an inductor, a combination exists where the lead time & lag time cancel, resulting in the current & voltage being in phase.

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**Components Resonance. This condition is called resonance.**

Resonant circuit. a.k.a. - Tuned circuit. Acts as filter. Used to adjust frequency of receiver or transmitter. The capacitive reactance (XC) and inductive reactance (XL) in a resonant circuit are equal. Impedance (Z) of a resonant circuit is purely resistive. Reactance = 0Ω.

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**T5C12 -- What is meant by the term impedance?**

It is a measure of the opposition to AC current flow in a circuit It is the inverse of resistance It is a measure of the Q or Quality Factor of a component It is a measure of the power handling capability of a component

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**T5C13 -- What are the units of impedance?**

Volts Amperes Coulombs Ohms

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**Resistor Zener diode Potentiometer Capacitor**

T6D08 -- Which of the following is used together with an inductor to make a tuned circuit? Resistor Zener diode Potentiometer Capacitor

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**T6D11 -- What is a simple resonant or tuned circuit?**

An inductor and a capacitor connected in series or parallel to form a filter A type of voltage regulator A resistor circuit used for reducing standing wave ratio A circuit designed to provide high fidelity audio

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Break

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**Components Diodes, Transistors, and Integrated Circuits.**

Resistors, capacitors, and inductors are linear devices. Response is ALWAYS directly proportional to the stimulus. Diodes and transistors are non-linear devices. Response is not always directly proportional to the stimulus.

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**Components Diodes, Transistors, and Integrated Circuits.**

The function of the diode is to allow the flow of current in only one direction. Connections named anode & cathode. Cathode normally identified with a stripe. An analogy is a check valve in a water pipe.

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**Components Diodes, Transistors, and Integrated Circuits.**

One use of a diode is as a rectifier in a power supply circuit to convert an AC voltage into a varying DC voltage.

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**Components Diodes, Transistors, and Integrated Circuits.**

Light-Emitting Diode (LED). Emits light when forward-biased.

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**Components Diodes, Transistors, and Integrated Circuits.**

The function of the transistor is to variably control the flow of current. Much like an electronically controlled valve. An analogy, the faucet in your sink.

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**Components Diodes, Transistors, and Integrated Circuits.**

Transistors can be used to amplify a signal. The amount of amplification is called “gain”. Transistors can be used to electronically turn the flow of current on or off like a switch.

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**Components Diodes, Transistors, and Integrated Circuits.**

Bipolar Transistors. Connections named Emitter, Base, & Collector. Small change in base current results in large change in emitter current. Low input & output impedances.

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Components Diodes, Transistors, and Integrated Circuits.

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**Components Diodes, Transistors, and Integrated Circuits.**

Field-Effect Transistors (FET). Connections named Source, Gate, & Drain. Small change in gate voltage results in large change in drain current. High input impedance & low output impedance.

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**Components Diodes, Transistors, and Integrated Circuits.**

An integrated circuit is a collection of components contained in one device that accomplishes a specific task. Acts like a “black-box”

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**Capacitors Inductors Resistors Transistors**

T6B01 -- What class of electronic components is capable of using a voltage or current signal to control current flow? Capacitors Inductors Resistors Transistors

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**Resistor Fuse Diode Driven Element**

T6B02 -- What electronic component allows current to flow in only one direction? Resistor Fuse Diode Driven Element

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**Oscillator Potentiometer Transistor Voltmeter**

T6B03 -- Which of these components can be used as an electronic switch or amplifier? Oscillator Potentiometer Transistor Voltmeter

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**Alternator Transistor Triode Pentagrid converter**

T6B04 -- Which of the following components can be made of three layers of semiconductor material? Alternator Transistor Triode Pentagrid converter

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**Electrolytic capacitor Multi-cell battery**

T6B05 -- Which of the following electronic components can amplify signals? Transistor Variable resistor Electrolytic capacitor Multi-cell battery

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**All of these choices are correct**

T6B06 -- How is the cathode lead of a semiconductor diode usually identified? With the word cathode With a stripe With the letter C All of these choices are correct

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**T6B07 -- What does the abbreviation LED stand for?**

Low Emission Diode Light Emitting Diode Liquid Emission Detector Long Echo Delay

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**T6B08 -- What does the abbreviation FET stand for?**

Field Effect Transistor Fast Electron Transistor Free Electron Transition Field Emission Thickness

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**T6B09 -- What are the names of the two electrodes of a diode?**

Plus and minus Source and drain Anode and cathode Gate and base

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**T6B10 -- What are the three electrodes of a PNP or NPN transistor?**

Emitter, base, and collector Source, gate, and drain Cathode, grid, and plate Cathode, drift cavity, and collector

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**Emitter, base, and collector Source, gate, and drain **

T6B11 -- What at are the three electrodes of a field effect transistor? Emitter, base, and collector Source, gate, and drain Cathode, grid, and plate Cathode, gate, and anode

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**Gain Forward resistance Forward voltage drop On resistance**

T6B12 -- What is the term that describes a transistor's ability to amplify a signal? Gain Forward resistance Forward voltage drop On resistance

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**Transformer Rectifier Amplifier Reflector**

T6D01 -- Which of the following devices or circuits changes an alternating current into a varying direct current signal? Transformer Rectifier Amplifier Reflector

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**LED FET Zener diode Bipolar transistor**

T6D07 -- Which of the following is commonly used as a visual indicator? LED FET Zener diode Bipolar transistor

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**Transducer Multi-pole relay Integrated circuit Transformer**

T6D09 -- What is the name of a device that combines several semiconductors and other components into one package? Transducer Multi-pole relay Integrated circuit Transformer

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**T6D10 -- What is the function of component 2 in Figure T1?**

Give off light when current flows through it Supply electrical energy Control the flow of current Convert electrical energy into radio waves

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**Components Protective Components.**

Fuses and circuit breakers are designed to interrupt the flow of current if the current becomes too large.

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Components Protective Components. Fuses blow. One-time protection.

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**Components Protective Components. Circuit breakers trip.**

Can be reset & reused.

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**Components Circuit Gatekeepers. Switches**

The function of the switch is to turn the flow of current on or off or to redirect it.

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**Components Circuit Gatekeepers. Relays.**

An electrically-controlled switch. A set of switch contacts connected to an electromagnet.

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**Components Circuit Gatekeepers. Indicators and displays.**

An indicator displays on/off status. A meter shows a value on a numeric scale. A display consists of several indicators & meters.

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**All of these choices are correct**

T6A08 -- What electrical component is used to connect or disconnect electrical circuits? Magnetron Switch Thermistor All of these choices are correct

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**All of these choices are correct**

T6A09 -- What electrical component is used to protect other circuit components from current overloads? Fuse Capacitor Inductor All of these choices are correct

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**T6D02 -- What best describes a relay?**

A switch controlled by an electromagnet A current controlled amplifier An optical sensor A pass transistor

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**Single-pole single-throw Single-pole double-throw **

T6D03 -- What type of switch is represented by component 3 in figure T2? Single-pole single-throw Single-pole double-throw Double-pole single-throw Double-pole double-throw

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**Potentiometer Transistor Meter Relay**

T6D04 -- Which of the following can be used to display signal strength on a numeric scale? Potentiometer Transistor Meter Relay

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**T0A04 -- What is the purpose of a fuse in an electrical circuit?**

To prevent power supply ripple from damaging a circuit To interrupt power in case of overload To limit current to prevent shocks All of these choices are correct

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**The power supply ripple would greatly increase **

T0A05 -- Why is it unwise to install a 20-ampere fuse in the place of a 5-ampere fuse? The larger fuse would be likely to blow because it is rated for higher current The power supply ripple would greatly increase Excessive current could cause a fire All of these choices are correct

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**Components Schematics and Component Symbols Schematic diagrams**

Use a set of standard symbols for each component in a circuit. Represent the way components are interconnected. Do NOT represent the physical layout of the components. Do NOT represent the length of the conductors used for the interconnections.

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Components Schematics and Component Symbols Schematic diagrams

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Components Schematics and Component Symbols Schematic diagrams

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**Electrical depictions Grey sketch Schematic symbols Component callouts**

T6C01 -- What is the name for standardized representations of components in an electrical wiring diagram? Electrical depictions Grey sketch Schematic symbols Component callouts

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**T6C02 -- What is component 1 in figure T1?**

Resistor Transistor Battery Connector

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**T6C03 -- What is component 2 in figure T1?**

Resistor Transistor Indicator lamp Connector

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**T6C04 -- What is component 3 in figure T1?**

Resistor Transistor Lamp Ground symbol

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**T6C05 -- What is component 4 in figure T1?**

Resistor Transistor Battery Ground symbol

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**T6C06 -- What is component 6 in figure T2?**

Resistor Capacitor Regulator IC Transistor

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**T6C07 -- What is component 8 in figure T2?**

Resistor Inductor Regulator IC Light emitting diode

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**T6C08 --- What is component 9 in figure T2?**

Variable capacitor Variable inductor Variable resistor Variable transformer

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**T6C09 -- What is component 4 in figure T2?**

Variable inductor Double-pole switch Potentiometer Transformer

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**T6C10 -- What is component 3 in figure T3?**

Connector Meter Variable capacitor Variable inductor

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**T6C11 -- What is component 4 in figure T3?**

Antenna Transmitter Dummy load Ground

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**Electrical components Logic states Digital codes Traffic nodes**

T6C12 -- What do the symbols on an electrical circuit schematic diagram represent? Electrical components Logic states Digital codes Traffic nodes

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**Physical appearance of components **

T6C13 -- Which of the following is accurately represented in electrical circuit schematic diagrams? Wire lengths Physical appearance of components The way components are interconnected All of these choices are correct

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**Types of Radios and Radio Circuits**

Basic 2-Way Radio Station.

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**Types of Radios and Radio Circuits**

Transmit-Receive Switches. Switches antenna between antenna and receiver. Transceivers include the T/R switch as an internal circuit. External T/R switch required if separate transmitter & receiver are used.

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**Types of Radios and Radio Circuits**

Oscillators and Amplifiers. Oscillators produce a steady AC voltage on a single frequency. Used in both receivers & transmitters to determine operating frequency. Crystal-controlled oscillator. Variable-frequency oscillator (VFO).

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**Types of Radios and Radio Circuits**

Oscillators and Amplifiers. Amplifiers increase the strength of a signal. Increase voltage, current, or power. Amount of increase is called “gain”. Numeric value – For example, a gain of 10 means the output signal is 10 times bigger than input signal. dB – For example, a power gain of 3 dB means the output signal has twice the power than the input signal.

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**Types of Radios and Radio Circuits**

Filters. Allow wanted signals to pass through. Prevent unwanted signals from passing through. Filters constructed using all passive components (resistors, capacitors, & inductors) are called “passive” filters. Fitters that include an amplifier are called “active” filters.

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**Types of Radios and Radio Circuits**

Filters. There are 4 basic classifications of filters: Low-pass filter. High-pass filter. Band-pass filter. Band reject filter. a.k.a. – notch filter.

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**Types of Radios and Radio Circuits**

Modulators. The process of combining information (voice, data, etc.) signals with an RF signal (carrier) is called “modulation”. Can be as simple as an on-off switch. Telegraph key. Can be very complex. A “demodulator” extracts the original information signal from the carrier.

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**Types of Radios and Radio Circuits**

Mixers. Mixers combine 2 different frequency signals together to produce 4 output frequencies. f1 x f2 f1, f2, f1-f2, & f1+f2. Usually only one output frequency wanted, so filters remove other 3 frequencies. Used in both transmitters & receivers. Used to shift a signal or group of signals to another frequency.

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**Phase splitter Mixer Inverter Amplifier**

T7A03 -- Which of the following is used to convert a radio signal from one frequency to another? Phase splitter Mixer Inverter Amplifier

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**Reactance modulator Product detector Low-pass filter Oscillator**

T7A05 -- What is the name of a circuit that generates a signal of a desired frequency? Reactance modulator Product detector Low-pass filter Oscillator

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**Impedance matching Oscillation Modulation Low-pass filtering**

T7A08 -- Which of the following describes combining speech with an RF carrier signal? Impedance matching Oscillation Modulation Low-pass filtering

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**Types of Radios and Radio Circuits**

Receivers. A receiver gets the desired RF signal from the antenna and presents the original information to the user. Many different types of receivers. Direct-conversion. If you count cell phones, most common type. Superheterodyne. Most common type used by amateur radio operators.

157
**Types of Radios and Radio Circuits**

Receivers. Direct-conversion receiver. Local oscillator at (or near) frequency of signal to be received. Advantage: Very easy to filter at audio frequency. Advantage: No image responses. Disadvantage: High stability local oscillator required. Most software-defined radios (including cell phones) use direct-conversion receivers.

158
**Types of Radios and Radio Circuits**

Receivers. Heterodyne receiver. RF & local oscillator fed into mixer to move signal to a lower intermediate frequency (IF) for filtering & demodulation. Advantage: Easier to filter at lower frequency. Disadvantage: Image responses. Superheterodyne. fLO > fRF.

159
**Types of Radios and Radio Circuits**

Receivers. Heterodyne receiver.

160
**Types of Radios and Radio Circuits**

Receivers. Sensitivity is a measure of how weak a signal can be received. Sometimes a pre-amplifier (pre-amp) is installed between the antenna and the mixer to improve sensitivity.

161
**Types of Radios and Radio Circuits**

Receivers. Selectivity is a measure of how well a receiver can differentiate between signals. Filters are used to provide selectivity.

162
**Types of Radios and Radio Circuits**

Transverters. The heterodyne method of shifting a frequency or range of frequencies can be used to shift a transceiver to a whole different band. Allows HF transceiver to be used on VHF, UHF, & microwave frequencies. Many amateur radio satellites are transverters.

163
**Total Harmonic Distortion**

T7A01 -- Which term describes the ability of a receiver to detect the presence of a signal? Linearity Sensitivity Selectivity Total Harmonic Distortion

164
**Discrimination ratio Sensitivity Selectivity Harmonic Distortion**

T7A04 -- Which term describes the ability of a receiver to discriminate between multiple signals? Discrimination ratio Sensitivity Selectivity Harmonic Distortion

165
**High-pass filter Low-pass filter Transverter D. Phase converter**

T7A06 -- What device takes the output of a low-powered 28 MHz SSB exciter and produces a 222 MHz output signal? High-pass filter Low-pass filter Transverter D. Phase converter

166
**T7A11 -- Where is an RF preamplifier installed?**

Between the antenna and receiver At the output of the transmitter's power amplifier Between a transmitter and antenna tuner At the receiver's audio output

167
Questions?

168
**Chapter 4 Propagation, Antennas, and Feed Lines**

Next Week Chapter 4 Propagation, Antennas, and Feed Lines

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Technician License Course Chapter 3 Electricity, Components and Circuits Lesson Plan Module 5 Presented by: The Brookhaven National Laboratory Amateur.

Technician License Course Chapter 3 Electricity, Components and Circuits Lesson Plan Module 5 Presented by: The Brookhaven National Laboratory Amateur.

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