UJT Triggering Circuit

The supply voltage of the secondary winding of transformer is rectified by the half wave rectifier diodes and given to the zener diode. The zener diode is used to clip the rectified to a fixed voltage This voltage is applied to the charging circuit R. The capacitor charges through the resistor R.

ujt trigger

    When the voltage across the capacitor reaches the UJT triggering  voltage, the UJT turns ON.  At this instant, the capacitor discharges through emitter (E), base (B1) and primary of pulse transformer. A pulse is produced at the primary, as well as at the secondaries  of the transformer.

When the capacitor discharges to a voltage called vally voltage the UJT  turns-off and capacitor charges again and the whole process repeats itself. The charging of the capacitor can be varied by varying the value of resistance R and therefore the firing angle can be controlled form 0 to 180 Degrees.

Subramanian
Subramanian

Subramanian MK, currently serving as a workshop instructor at Sakthi Polytechnic College, Erode Tamil Nadu. With a career spanning 25 + years, Subramanian MK has dedicated himself to advancing knowledge in Electronics and Communication Engineering (ECE). His passion for exploring new technologies has led to the development of numerous projects, showcasing expertise in IoT and PCB design.

Articles: 501

2 Comments

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

×

Hi, How can I help you?

×