Medha Servo Drives Interview Questions and Answers

Latching current is the minimum current required to maintain a relay or contactor in its energized state.

• Latching current is crucial for electromagnetic devices like relays and contactors.

• It ensures that once activated, the device remains on without continuous power.

• For example, in a relay, if the latching current is 10 mA, it must maintain at least this current to stay closed.

• If the current drops below this level...read more

MOSFETs are voltage-controlled devices, while IGBTs combine features of MOSFETs and BJTs for high-power applications.

• MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is primarily used for low to medium power applications.

• IGBT (Insulated Gate Bipolar Transistor) is suitable for high power and high voltage applications, like in inverters.

• MOSFETs have faster switching speeds compared to IGBTs, making them i...read more

A 12 K resistor has a color code of red, black, orange, and gold indicating its value and tolerance.

• The first band (red) represents the first digit: 2.

• The second band (black) represents the second digit: 0.

• The third band (orange) indicates the multiplier: 10^3 (or 1000).

• Combining these gives 20 x 1000 = 20,000 ohms, but for a 12K resistor, we consider the tolerance.

• The fourth band (gold) indicates a tolerance of ±...read more

A full wave rectifier converts AC to DC using diodes, allowing current to flow in both halves of the AC cycle.

• Uses two or four diodes in a bridge configuration.

• Inverts the negative half of the AC signal to positive.

• Results in a smoother DC output compared to half-wave rectifiers.

• Commonly used in power supplies for electronic devices.

Design a circuit to convert 72 V DC to a stable 5 V DC output using a voltage regulator.

• Use a step-down transformer to reduce voltage if AC input is available.

• Implement a linear voltage regulator (e.g., LM7805) for stable 5 V output.

• Consider using a buck converter for higher efficiency in DC-DC conversion.

• Add filtering capacitors to smooth out the output voltage.

• Ensure proper heat dissipation for components handli...read more

Potential difference, or voltage, is the work done per unit charge to move a charge between two points in an electric field.

• Measured in volts (V), it indicates the energy difference between two points.

• Example: A battery provides a potential difference that drives current in a circuit.

• It can be thought of as the 'pressure' that pushes electric charges through a conductor.

• In a circuit, higher potential difference re...read more

A full adder can be implemented using 2 universal gates: NAND or NOR.

• A full adder has three inputs: A, B, and Carry-in (Cin).

• It produces two outputs: Sum and Carry-out (Cout).

• Using NAND gates, a full adder can be constructed with 4 NAND gates.

• Using NOR gates, a full adder can also be constructed with 6 NOR gates.

• Universal gates can create any logic function, including adders.

Rectifiers convert AC to DC and come in various types, each with unique operational characteristics.

• 1. Half-Wave Rectifier: Uses one diode to allow only one half of the AC waveform, resulting in pulsating DC. Example: Simple power supply circuits.

• 2. Full-Wave Rectifier: Utilizes two diodes or a bridge configuration to convert both halves of the AC waveform into DC. Example: Bridge rectifier circuits.

• 3. Center-Tapp...read more