Electronics Measurement Techniques Quiz

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Questions and Answers

What is defined as the time needed for a pulse to increase from 10% to 90% of its amplitude?

Pulse width

Duty cycle

Propagation delay

Rise time (correct)

Which device is most effective for detecting shorted tracks in a circuit?

Current tracer (correct)

Oscilloscope

Logic pulser

Multimeter

How can direct current be measured accurately?

By a DC potentiometer in conjunction with a standard resistance (correct)

Directly by a DC potentiometer

By a DC potentiometer in conjunction with a volt ratio box

None of the above

Which of the following galvanometers are classified as permanent magnet moving coil instruments?

D'Arsonval Signup and view all the answers

What does not accurately represent the measurement properties of an oscilloscope?

Measures resistance directly Signup and view all the answers

What could cause a +5 V PCB power source to drop to +3.4 V?

A circuit short Signup and view all the answers

When measuring pulse width, what reference point should be used?

Rise and fall Signup and view all the answers

Which equipment is most effective for comparing input and output signals?

A multitrace oscilloscope Signup and view all the answers

How is the duty cycle of a pulse calculated?

Duty Cycle = pw/t x 100% Signup and view all the answers

What should be done after identifying a faulty gate in an integrated circuit (IC)?

Replace the IC involved Signup and view all the answers

What can a multimeter measure effectively in digital circuits?

Voltage or resistance Signup and view all the answers

What advantage does a triggered sweep provide when using an oscilloscope?

More accurate time base Signup and view all the answers

For determining voltage levels in a circuit, which instrument would be most appropriate?

A multimeter Signup and view all the answers

What is the term length for members of the Board as stated in section 9 of RA 9292?

Three years Signup and view all the answers

In which section of RA 9292 are the compensation and allowances of the Board of Electronics Engineering specified?

Section 10 Signup and view all the answers

What section of RA 9292 mandates that all applicants for registration as Electronics Engineers and Technicians must undergo examinations?

Section 13 Signup and view all the answers

How long do members of the Board serve before needing reappointment as per the relevant RA 9292 section?

Three years Signup and view all the answers

Which section of RA 9292 states the qualifications required for members of the Board?

Section 9 Signup and view all the answers

What happens to an atom that loses an electron?

It becomes a positive ion Signup and view all the answers

Which type of material is primarily used to make permanent magnets?

Steel Signup and view all the answers

What effect does an electric current have on a conductor?

Produce a magnetic field Signup and view all the answers

Which of the following best defines a semiconductor?

An element that has variable conductivity Signup and view all the answers

What term describes the opposition to the flow of electrical current?

Resistance Signup and view all the answers

Which type of connection improves the voltage handling capability of capacitors?

Series connection Signup and view all the answers

What is the primary function of an isolating transformer?

Eliminate all potential ground voltage Signup and view all the answers

What characteristic of the lead-acid battery distinguishes it from a standard torch battery?

It can be recharged Signup and view all the answers

How does resistance in a metallic conductor change as temperature increases?

It increases Signup and view all the answers

What role does the earth wire play in a mains power supply?

Ensures chassis does not gain high voltage Signup and view all the answers

Which section of RA 10912 pertains to the Declaration of Policy?

Section 2 Signup and view all the answers

Which is the correct colour coding for the neutral wire in a flexible mains lead?

Blue Signup and view all the answers

What happens to the total capacitance of capacitors connected in series?

It is always less than the smallest capacitor Signup and view all the answers

What ensures that a transmitter is free from SWR effects?

Well insulated wires Signup and view all the answers

Which type of scale is used for a moving iron instrument?

An uneven scale measuring d.c. and a.c. Signup and view all the answers

What type of resistance is needed to extend a milliammeter's range for 100 V measurements?

A series high-value resistance Signup and view all the answers

What is a major safety concern when working with transformerless power supplies?

One side of the line cord is connected to the chassis Signup and view all the answers

Which of these corresponds to a moving coil rectifier instrument?

An even scale measuring a.c. Signup and view all the answers

When should a parallel high-value resistance be utilized with a milliammeter?

To reduce the load on the circuit being measured Signup and view all the answers

How does the connection of a power supply chassis impact safety?

It creates a potential shock hazard Signup and view all the answers

What can be a consequence of an uneven scale measuring a.c.?

Inaccurate readings for d.c. Signup and view all the answers

What is the key feature of a hand-held transceiver's antenna when transmitting?

It should be oriented vertically for better range Signup and view all the answers

Study Notes

RA 10912

Known as Continuing Professional Development Act of 2016
Section 2: Declaration of Policy
Section 3: Definition of Terms
Section 4: Strengthening CPD Programs
Section 5: Nature of the CPD Programs
Section 6: Powers, Function and Responsibilities of the PRC and Board
Section 7: CPD Council
Section 8: Power, Functions and Responsibilities of CPD Council
Section 9: Secretariat
Section 15: Implementing Rules and Regulations
Section 16: Fraud Relating to CPD
Section 17: Separability Clause
Section 18: Repealing Clause
Section 19: Effectivity Clause

RA 10175

Known as Cybercrime Prevention Act of 2012

Capacitors

Capacitors in series have a total capacitance that is always less than the smallest capacitor in the series.
Filter capacitors in power supplies can be connected in series to withstand a greater voltage than a single capacitor can withstand.

Electrical Safety

It's safe to remove an unconscious person from contact with a high voltage source by turning off the high voltage and then removing the person.
Before checking a fault in a mains operated power supply unit, turn off the power and remove the power plug.
Isolating transformers ensure that no voltage is developed between either output lead and ground.

Mains Power

The correct colour coding for wires in a flexible mains lead:
- Phase: Brown
- Neutral: Blue
- Earth: Yellow and green
A residual current device removes power to the circuit when the phase and neutral currents are not equal.
An earth wire connected to the metal chassis of a mains-operated power supply ensures that if a fault develops, the chassis does not develop a high voltage with respect to earth.

Superhet Receiver

An RF amplifier ahead of the mixer stage in a superhet receiver increases the sensitivity of the receiver.

Miscellaneous

"Train" and "single" are mode selections for an amateur radio transceiver.

A +5 V PCB power source pulled down to 3.4 V

A +5 V PCB power source that is "pulled down" to +3.4 V is most likely due to a circuit short.
A circuit short is an unexpected connection between two conductive parts of an electrical circuit.
This can happen for various reasons, including faulty components, damaged wires, or manufacturing defects, resulting in a lower-than-expected voltage.

Pulse Width measurement

Pulse width measurement is taken at the 50% mean of the rise and fall.
The rise time of a pulse is the time it takes for the pulse to rise from 10% to 90% of its amplitude.
The fall time of a pulse is the time it takes for the pulse to fall from 90% to 10% of its amplitude.

Multitrace Oscilloscope

A multitrace oscilloscope is the best test equipment for comparing input and output signals.
It allows the simultaneous display of multiple signals, facilitating a direct comparison of the input and output waveforms.
This allows for a clear observation of any signal modifications, distortions, or delays that occur as the signal passes through a circuit.

Calculating Duty Cycle

The duty cycle of a pulse is calculated using the following formula: Duty Cycle = pw/t x 100%, where:
- pw is the pulse width.
- t is the period of the pulse train.
The duty cycle represents the percentage of time the pulse is "on" within a complete cycle.

Replacing Faulty ICs

If a faulty gate within an IC is discovered, the next step is to replace the IC.
Direct repair of a faulty gate within an IC is typically not feasible, as the internal circuitry cannot be easily accessed or modified.
Replacing the involved IC is usually the most practical approach, ensuring proper circuit operation.

Using a Multimeter with Digital Circuits

A multimeter can measure the voltage or resistance in a digital circuit.
It is able to measure the voltage across different component terminals or the resistance between points in a circuit.

Triggered Sweep with an Oscilloscope

Triggered sweep is used in oscilloscopes to increase accuracy in timing.
It allows for a more stable and repeatable display of the waveform, particularly when examining signals with varying frequency or timing characteristics.
It synchronizes the horizontal sweep of the oscilloscope with the signal being measured.

Shorted Track Detection

A current tracer is the most effective device for detecting shorted tracks.
It is a specialized tool designed to follow the flow of current in a circuit.
By injecting a small current and tracing its path, it can identify any unintended current paths or short circuits.

Measuring Direct Current

A direct current can be measured by a dc potentiometer in conjunction with a standard resistance.
A potentiometer is a variable resistor that is used to measure voltage accurately.
By adjusting the potentiometer to balance the voltage drop across the standard resistance with the voltage being measured, the value of the direct current can be determined.

Permanent Magnet Moving Coil Instruments

Permanent magnet moving coil instruments are associated with an even scale, measuring d.c.
They are often used for measuring direct current due to their high accuracy, sensitivity, and relatively low cost.
These instruments are characterized by a moving coil that rotates in a permanent magnetic field, resulting in even markings on the scale.

Moving Iron Instruments

Moving iron instruments are associated with an uneven scale, measuring d.c. and a.c.
They are used for measuring both direct and alternating current.
The scale is often non-linear because the force exerted on the iron element is not proportional to the current.

Moving Coil Rectifier Instruments

Moving coil rectifier instruments are associated with an even scale, measuring a.c.
These instruments work by using a rectifier circuit to convert alternating current to direct current, which is then measured by a moving coil instrument.
To achieve accurate readings, the rectifier circuit is typically designed to provide a smooth direct current output.

Extending a Milliammeter's Range

A series high-value resistance is needed to extend the range of a milliammeter to read voltages of the order of 100 V.
Adding a series resistor reduces the current flowing through the milliammeter, allowing it to measure higher voltage readings.
The value of the series resistance is determined by the desired voltage range.

Transformerless Power Supplies

Transformerless power supplies have one side of the line cord connected to the chassis. This presents a safety hazard because the chassis can become "live" at a dangerous voltage, even when the device is seemingly off.

Hand-held Transceiver Antenna Position

The antenna of a hand-held transceiver should be positioned vertically while you are transmitting.
This orientation generally provides the best radiation pattern and ensures optimal signal strength.

Section 9 of RA 9292 - Board Members Term

The members of the Board of Electronics Engineering hold office for a term of three years from the date of their appointment, according to Section 9 of RA 9292.

Section 10 of RA 9292- Board Compensation

The compensation and allowances of the board of electronics engineering are stated in Section 10 of the Republic Act 9292.

Section 13 of RA 9292- Examinations for Licensing

Section 13 of RA 9292 states that all applicants who wish to be registered and licensed as Electronics Engineers and Electronics Technicians must undergo the required examinations given by the Board.

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Description

Test your knowledge of key concepts in electronics measurement with this quiz. Questions cover pulse measurements, oscilloscopes, multimeters, and circuit diagnostics. See how well you understand various tools and methods used in electronic testing and troubleshooting.