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Emitter Voltage To Turn On Ujt Based Thyristor Firing Circuit Formula:
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The Emitter Voltage To Turn On Ujt Based Thyristor Firing Circuit is defined as the voltage required at the emitter terminal to trigger the UJT (Unijunction Transistor) in thyristor firing circuits, calculated as the sum of the voltage across the base 1 resistance and the diode voltage.
The calculator uses the formula:
Where:
Explanation: This formula calculates the minimum emitter voltage needed to turn on the UJT in thyristor firing circuits by summing the voltage drop across the base 1 resistance and the forward voltage of the diode.
Details: Accurate calculation of emitter voltage is crucial for proper triggering of UJT-based thyristor circuits, ensuring reliable firing of thyristors in power control applications and timing circuits.
Tips: Enter the emitter resistance base 1 voltage and diode voltage in volts. Both values must be non-negative numbers.
Q1: What is a UJT in thyristor firing circuits?
A: A Unijunction Transistor (UJT) is used as a relaxation oscillator to generate triggering pulses for thyristors in power control applications.
Q2: Why is diode voltage included in the calculation?
A: The diode voltage represents the forward voltage drop across the diode in the circuit, which must be overcome for proper triggering.
Q3: What are typical values for V_RB1 and V_d?
A: Typical values depend on circuit design, but V_RB1 is usually a fraction of the supply voltage, and V_d is typically 0.6-0.7V for silicon diodes.
Q4: How does this affect thyristor firing angle?
A: The emitter voltage determines when the UJT triggers, which directly controls the firing angle of the thyristor in the circuit.
Q5: Can this formula be used for all UJT circuits?
A: This formula applies specifically to UJT-based thyristor firing circuits where the emitter voltage is the sum of base 1 resistance voltage and diode voltage.