On this page, we will review the Analog Electronics Short Notes PDF Part 31. Welcome to Poly Notes Hub, a leading destination for analog electronics notes for engineering students.
Author Name: Arun Paul
Analog Electronics Short Notes Pdf Part 31
Here we have listed some analog electronics short notes for all types of exams like diploma engineering, degree engineering, and GATE exam and many more. In every page, we have listed 10 short analog electronics questions and answers and anyone can download it by a single click for future use.
1. What is UJT?
UJT (Uni-Junction Transistor) is a three-terminal semiconductor device used mainly for triggering and timing applications. It has only one junction and exhibits negative resistance characteristics.
2. What are the terminals of UJT?
The three terminals of a UJT are: Emitter (E), Base 1 (B1), and Base 2 (B2).
3. What is the operation of UJT?
When the emitter voltage reaches a certain threshold (called peak point voltage), the UJT starts conducting between the emitter and B1, causing a sudden increase in current and a decrease in voltage, leading to a negative resistance region. It continues until the current drops below the holding value.
4. What is Negative Resistance Region?
The negative resistance region in UJT operation is the part of the characteristic curve where an increase in emitter current causes a decrease in emitter voltage, allowing the device to be used in oscillator circuits.
5. What is Saturation Region?
The saturation region in a UJT occurs after the negative resistance region, where the UJT conducts heavily and both junctions are forward-biased, resulting in a low voltage drop across the device.
6. What is Leakage Current in UJT?
Leakage current in UJT is the small current that flows between the emitter and base when the emitter voltage is below the peak point voltage, and the UJT is in its OFF state.
7. What are the advantages of UJT?
UJT offers simple construction, low cost, low power consumption, and excellent triggering performance, especially in oscillator and pulse generation circuits.
8. What are the applications of UJT?
UJT is used in sawtooth wave generators, pulse generators, triggering circuits for SCRs, relaxation oscillators, and timing circuits.
9. What is UJT Relaxation Oscillator?
A UJT relaxation oscillator is a circuit that generates non-sinusoidal waveforms like sawtooth or pulse waveforms using the charging and discharging of a capacitor through the UJT’s negative resistance region.
10. Explain about Overvoltage Detector using UJT.
In an overvoltage detector using UJT, the UJT is biased such that it remains OFF under normal voltage. When the input voltage exceeds a certain threshold, the UJT turns ON and triggers a connected alarm or protection circuit, thus indicating an overvoltage condition.