Gibilisco - Power Supplies Quiz

Full-wave bridge rectification is advantageous because it utilizes the entire transformer secondary for the entire AC input cycle. This means that both the positive and negative halves of the AC waveform are utilized, resulting in a more efficient conversion of AC to DC. This allows for a higher average output voltage and a smoother DC output compared to other rectifier types that only utilize half of the AC wave cycle.

A television broadcast transmitter would need the biggest transformer because it requires a large amount of power to transmit television signals over long distances. Transmitters typically operate at high power levels, often in the kilowatt range, compared to the other appliances listed. Therefore, it would require a larger transformer to handle the higher power demands of the television broadcast transmitter compared to the other appliances.

A rectifier circuit converts alternating current (ac) into direct current (dc). However, without a filter included, the output of the rectifier circuit will still contain ripples or variations in voltage. This type of output is known as pulsating dc, where the voltage rises and falls but does not reverse direction like in ac. Therefore, the correct answer is pulsating dc.

If a fuse blows and it is replaced with one having a lower current rating, there is a good chance that the fuse will blow out right away. This is because a fuse is designed to protect the circuit by blowing and breaking the circuit when the current exceeds its rating. By replacing it with a fuse of lower current rating, it will not be able to handle the current flowing through the circuit, causing it to blow out immediately.

In order to produce a 12-V dc output with a 117-V rms ac input, all of the listed components are necessary. The transformer is needed to step down the voltage from the ac input to a suitable level for rectification. The rectifier is required to convert the ac input to dc output. Lastly, the filter is necessary to smooth out any remaining ripples or fluctuations in the dc output. Therefore, all of these components are essential for the power supply to function properly.

The full-wave, center-tap arrangement is the best rectifier circuit for a power supply designed to provide high power at low voltage. This circuit utilizes both halves of the input AC waveform, resulting in a higher average output voltage compared to the half-wave arrangement. The center-tap provides a reference point for the circuit, allowing for more efficient voltage conversion. Additionally, the full-wave arrangement reduces ripple and provides a smoother DC output, making it suitable for high-power applications. The quarter-wave arrangement and voltage doubler arrangement are not as efficient or effective in providing high power at low voltage.

A full-wave rectifier converts both the positive and negative halves of an alternating current (AC) signal into a direct current (DC) signal. This is achieved by using two diodes and a center-tapped transformer. Since the full-wave rectifier uses both halves of the AC signal, it produces twice as many pulses per cycle compared to a half-wave circuit. Therefore, the ripple frequency from a full-wave rectifier is twice that from a half-wave circuit.

The given answer, "is a quick-break type," is the correct explanation. A quick-break fuse is designed to quickly interrupt the flow of current when it exceeds a certain threshold. This type of fuse is commonly used in situations where the circuit needs to be protected from high current surges or short circuits. Since the fuse contains nothing but a straight wire, it suggests that it is designed to break the circuit rapidly in the event of excessive current flow.

A capacitor in parallel and a choke in series would make the best filter for a power supply. The capacitor in parallel helps to smooth out the voltage by storing and releasing electrical energy, while the choke in series helps to block high-frequency noise and ripple currents. This combination of components effectively filters out both high-frequency noise and low-frequency ripple, resulting in a cleaner and more stable power supply output.

A Zener diode connected in parallel with the filter output, reverse-biased, can be used for voltage regulation. When the voltage across the diode exceeds the Zener voltage, it starts conducting in reverse bias and maintains a constant voltage across it. This helps in regulating the output voltage and preventing it from exceeding a certain value.

If you are not completely familiar with a damaged power supply, the safest option is to leave it alone and have a professional work on it. Working with a power supply that you are not familiar with can be dangerous, as there may be potential hazards or risks that you are not aware of. It is always best to seek professional help in such situations to ensure your safety and the proper repair of the power supply.

The part of a power supply immediately preceding the regulator is the filter. The filter is responsible for removing any unwanted noise or fluctuations in the input voltage. It smooths out the rectified AC voltage from the transformer and ensures a stable and clean DC voltage is supplied to the regulator. This helps in providing a steady power output and protects the electronic components from any voltage spikes or disturbances.

A half-wave rectifier only allows the positive half of the input AC waveform to pass through, while blocking the negative half. This means that the output waveform will have a lower peak voltage than the input. Additionally, there will be some voltage drop across the rectifier diode. As a result, the effective DC output voltage will be considerably less than the peak voltage of the AC input.

Connecting two capacitor/choke filtering sections in cascade will yield the best results for ripple filtering in a power supply. This is because using two sections in cascade allows for a more effective reduction of ripple voltage. The first section, typically a capacitor, filters out high-frequency noise, while the second section, typically a choke, further filters out low-frequency noise. This combination of capacitors and chokes in cascade provides a more comprehensive filtering solution, resulting in exceptionally good ripple filtering.

The principal disadvantage of a voltage-doubler power supply circuit is poor regulation under heavy loads. This means that when the circuit is operating with a high power demand, it is unable to maintain a stable and consistent output voltage. This can lead to fluctuations in the power supply, causing potential damage to the connected devices or affecting their performance.

In a full-wave bridge circuit, the peak voltage across the diodes in the reverse direction is approximately 1.4 times the rms voltage of the transformer's secondary. Since the rms voltage is 50 V, the peak voltage would be 1.4 times that, which is 70 V pk.

When a power supply is first turned on, a current surge takes place because the filter capacitor(s) must be initially charged. The filter capacitor acts as a reservoir for electrical energy and helps in smoothing out the voltage fluctuations. When the power supply is turned on, the capacitor is initially discharged and needs to be charged up to its operating voltage. This sudden charging of the capacitor requires a large amount of current, resulting in a surge. Once the capacitor is fully charged, the current flow stabilizes.

Connecting multiple diodes in parallel helps distribute the surge current among the diodes, reducing the risk of destruction. By adding low-value resistors in series with each diode, it further limits the current flowing through each diode, providing additional protection. This technique ensures that the surge current is divided evenly and does not overload any individual diode, thus minimizing the risk of diode destruction.

Transient suppression is important because it helps to minimize the risk of diode failure. Transients, or sudden voltage spikes, can cause excessive current to flow through a diode, leading to its failure. By implementing transient suppression techniques such as using diode clamps or voltage suppressors, the voltage spikes can be limited, protecting the diodes from damage. This ensures the proper functioning and longevity of the diodes in electronic circuits.

In a voltage-doubler circuit, the peak output voltage (V_dc) can be approximated as twice the RMS (root mean square) voltage of the AC input when there is no load. 



Given that the transformer secondary provides 10-V RMS AC, we can calculate the approximate DC output voltage as follows:



V_dc ≈ 2 x V_rms

V_dc ≈ 2 x 10 V

V_dc ≈ 20 V



So, the approximate DC output voltage with no load is 20 volts.