Trying to explain how a Relaxation Oscillator UJT circuit works

In summary, UJT is a type of transistor with a single emitter and two bases. Its operation is dependent on the voltage at the emitter, with a breakthrough voltage (Vp) determining when it will conduct. The relation coefficient (η) is calculated using the resistance values at the two bases. The circuit described in the conversation uses a UJT and a capacitor to generate pulses, with the UJT opening up when the capacitor reaches Vp and allowing current to flow.
  • #1
Femme_physics
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http://img689.imageshack.us/img689/7084/ujte.jpg This is a Relaxation Oscillator circuit with UJT. I need to A) Explain what is UJT, explain its relation ratio of η for the UJT, and explain what Vp is. And in B) Explain how does the circuit work, and what is the output (or turnout) of the circuit

Trying to use my own wordsUJT is a uni-junction transistor that has a single emitter and two bases. As long as the voltage in the emitter is smaller than the breakthrough voltage (Vp) , the UJT acts as disconnection.
When the voltage in the emitter gets to the same voltage as Vp, the resistance at the base is broken through B1, and when the voltage in the emitter drops to a minimal value Uv, UJT is back to cutoff.

relation coeffcient - η = Rb1/(Rb1+Rb2)

Vp is "peak voltage" or "breakout" voltage. When the voltage in the emitter arrives to Vp then the UJT opens up (broken though).

(Hope I didn't lose anyone by now!)

B) This circuit generates pulses. Its made out of UJT and a capacitor. The capacitor is loaded from the source and when it reaches Vp, the UJT opens up and current flows from the Emitter through B1.
 
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  • #2
Well, I haven't learned about UJT's before, but after googling it I'm drawing the conclusion that you summed it up nicely. :)
Actually, I like your explanation better than some others on the internet.

I'm turning into an electronics expert thanks to you!
 
  • #3
Much appreciated :)
 

What is a relaxation oscillator UJT circuit?

A relaxation oscillator UJT (Unijunction Transistor) circuit is an electronic circuit that uses a unijunction transistor to generate a periodic waveform. It is commonly used to create square, triangle, or sawtooth waveforms for various applications such as signal generation, timing circuits, and voltage regulation.

How does a relaxation oscillator UJT circuit work?

A relaxation oscillator UJT circuit works by using the unique properties of a unijunction transistor. The transistor is connected in a feedback loop with a resistor, capacitor, and power supply. As the capacitor charges, the voltage across it increases until it reaches a threshold value. This triggers the transistor to turn on and discharge the capacitor, causing the voltage to drop. This cycle then repeats, creating a periodic oscillation.

What are the advantages of using a relaxation oscillator UJT circuit?

Some advantages of using a relaxation oscillator UJT circuit include its simplicity, low cost, and ability to generate a wide range of frequencies. It also has a relatively stable output compared to other types of oscillators.

What are the applications of a relaxation oscillator UJT circuit?

A relaxation oscillator UJT circuit is commonly used in electronic devices such as timers, alarms, pulse generators, and voltage regulators. It is also used in electronic music synthesizers to produce different types of waveforms.

How can I troubleshoot a relaxation oscillator UJT circuit?

If a relaxation oscillator UJT circuit is not working properly, some potential troubleshooting steps include checking the connections, replacing faulty components, and adjusting the values of the resistor and capacitor. It may also be helpful to consult the circuit's datasheet or seek assistance from a knowledgeable individual.

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