UJT Characteristics Apparatus

Quick Answer: The UJT Characteristics Apparatus is an electronics lab unit used to study the Unijunction Transistor (UJT) — plotting its emitter characteristic curve and demonstrating its negative-resistance region, which underlies its common use in relaxation-oscillator and trigger circuits.

A UJT behaves very differently from a standard BJT: past a threshold emitter voltage it exhibits negative resistance, causing the emitter current to rise sharply. This apparatus gives students a panel-mounted UJT with accessible terminals (Emitter, Base 1, Base 2) so they can wire up a test circuit, sweep the emitter voltage, and record the corresponding current to plot the characteristic curve and identify the peak point and valley point.

It is used in electrical/electronics engineering laboratories, diploma and polytechnic courses, to support practical sessions on unijunction transistor characteristics and UJT relaxation oscillator theory, both of which are standard topics in analog electronics and power electronics curricula.

Key Features

• Panel-mounted UJT with clearly labelled Emitter, Base 1 (B1), and Base 2 (B2) terminals
• Layout suitable for tracing the full emitter characteristic curve, including the negative-resistance region
• Compact bench-top construction for use alongside a regulated DC supply and standard meters
• Useful for demonstrating peak-point and valley-point voltage/current readings
• Supports lab exercises that lead into UJT relaxation-oscillator circuit design

Specifications

Safety Note

Operate this apparatus only within the emitter voltage and current ratings appropriate for the mounted UJT — the device’s negative-resistance behaviour means current can rise rapidly past the peak point, so use a current-limited supply and monitor readings closely. Observe correct terminal polarity for Emitter, B1, and B2, and disconnect the power supply before altering any wiring. Recommended for supervised use in a teaching lab setting.

Why Choose LabEquip

LabEquip supplies electronics and electrical trainer apparatus to engineering colleges, polytechnics, and technical training institutes. Explore related boards and modules from our Electrical and Electronics range to build out a complete semiconductor devices lab:

• Arduino Leonardo Board
• Wi-Fi Serial Module
• Discrete Electronics Trainer Kit

Frequently Asked Questions

What does the UJT Characteristics Apparatus demonstrate?

It demonstrates the emitter characteristic curve of a Unijunction Transistor (UJT), including its distinctive negative-resistance region between the peak point and the valley point.

What terminals does the apparatus provide?

It provides access to the Emitter (E), Base 1 (B1), and Base 2 (B2) terminals of the mounted UJT so students can wire an external test circuit.

Why is the negative-resistance region important?

The negative-resistance region is what allows a UJT to be used in relaxation-oscillator and trigger circuits — a topic this apparatus helps students visualise directly from measured readings.

Is the UJT device included with the apparatus?

This is not specified for the current listing. Please confirm exactly what is included with our sales team before ordering.

Do I need an external power supply?

Yes, the apparatus is used with an external regulated DC power supply; whether one is bundled with a specific order is not specified for this listing — confirm with our sales team.

Who is this apparatus intended for?

It is intended for undergraduate electrical/electronics engineering students, diploma and polytechnic learners, and technical training institutes covering UJT characteristics as part of an analog or power electronics course.

Last Updated: September 2026