Why ujt is used as relaxation oscillator

Resistor R and capacitor C determines the frequency of the oscillator. When power supply is switched ON the capacitor C starts charging through resistor R.

The capacitor keeps on charging until the voltage across it becomes equal to 0. After this point the emitter to RB1 resistance drops drastically and the capacitors starts discharging through this path. This cycle is repeated and results in a sort of sawtooth waveform across the capacitor. The saw tooth waveform across the capacitor of a typical UJT relaxation oscillator is shown in the figure below. Practical circuit diagram and testing of the UJT relaxation oscillator will be added soon.

Help on this question list four parameters that determines. Is that because equation written above for RE? Author jojo. Do you know how RFID wallets work and how to make one yourself? February 14, The fixed bias circuit as shown is used as a collector bias circuit. What is the value of RB? Q point 9. The transistor has a DC gain of The most widely used amplifier configuration is. Configuration of two transistors in which collectors are connected and emitter of first drives base of second, it achieves beta multiplication is called.

Find base current for CE configuration. The P-type material forms the emitter connection. In UJT the emitter terminal E is forward biased. When the Emitter terminal is applied with voltage greater than the voltage across the RB1, the device gets forward biased and starts conducting. The timing of the output waveform is determined using the RC time constant. Supply voltage VBB is applied to the circuit. The capacitor starts charging through the resistor R1.

The capacitor discharges through the resistor R2. The output voltage collected across R2 forms the non-sinusoidal waveform. This process of charging and discharging continues. The voltage across the capacitor when plotted on the graph shows a sweep waveform. This type of transistor can also be used in timing, trigger generator, and gate pulse applications.

This article discusses an overview of the UJT relaxation oscillator, circuit, and its working. Generally, a relaxation oscillator is a non-linear oscillator and the main function of this is to produce non-sinusoidal output waveforms like a square wave, triangular wave which triggers power control devices like TRIACs and SCRs.

These waveforms are also called non-sinusoidal signal generators. Similarly, a UJT relaxation oscillator is one kind of RC oscillator where the uni-junction transistor works as an active element. Here, VBB in the circuit is an external voltage supply. Let us discuss how a UJT relaxation oscillator generates a non-sinusoidal output signal.