Test: Power Controls - Computer Science Engineering (CSE) MCQ

Explanation: The darlington pair of transistors can provide high gain than a single transistor. This is one of the method used to avoid voltage mismatches that the system produces. By using high gain transistors the voltage mismatches can be reduced upto a limit.

Explanation: The buffer pack is used to avoid the voltage mismatches which possesses a high drive capacity and it can also provide high drive currents than the normal logic outputs.

Explanation: The field effect transistor can be used to provide a very high effective gain and hence they can be used to switch heavy loads easily from a logic device. These are also voltage controlled transistors.

Explanation: The H bridge can be created by using several switches which allows a DC motor to be switched on and reversed in the direction. The switching can be done by using two outputs and four FETs.

Explanation: The H bridge can be created by using several switches. This allows a DC motor to be switched on and reversed in the direction and the switching of DC motor can be done by using two outputs and four FETs.

Explanation: The H bridge is used in controlling DC motors or any other loads which need voltage reversing.

Explanation: The light emitting diodes are used as indicators in the digital system and can be directly driven from a logic output.

Explanation: The LEDs will light up only when the diode reverse breakdown is achieved. It is usually about 2 to 2.2V.

Explanation: The current drive determines the brightness of the LEDs and it is usually associated with a current limiting resistor in series with the LED to prevent the overheating.

Explanation: A buffer can be used as a current limiting device. Similarly a transistor can also be used as a current limiting device.

Explanation: The relays are a kind of switching power in which the logic signal is used to energise the relay. The relay contacts are break or make accordingly and helps in switching the current.

Explanation: The relay generates a back voltage across its terminals when the logic output switches from a high to low state.

Explanation: In order to get rid of the back EMF which is generated by the relay a diode is connected across the terminals which operates in the reverse bias, so that nothing can harm the relay.

Explanation: The pulse width modulation can provide a speed control technique in the DC motor interfacing by changing its mark/space ratio.

Explanation: In the software system, certain loops perform the timing functions. A program is created to switch the motor on and it will start counting through a delay loop. When the count is finished, the motor is switched off. In the second delay loop, it can determine the motor-off period.