Maker's Name: 
UQ Physics Electronic Workshop
12.8 × 14.5 × 14.5 cm

This apparatus is designed to determine a B/H curve for a transformer and to teach students to use an oscilloscope.

A small transformer inside the box has a primary 240 V winding and a 50 V secondary winding. The primary current is sensed by measuring the voltage across a series resistor and applied to the H output terminal. (H is the magnetic induction, measured in amps/m)

The voltage across the secondary winding is integrated by a capacitor and applied to the B output terminals. (B is the magnetic flux density measured in tesla)

An oscilloscope is set up in X-Y configuration with the H terminal connected to the X-axis input and the B terminal to the Y-axis input.

The screen display then shows the B/H characteristic of the transformer core material. A straight diagonal line would indicate a lossless core material.

A lightly loaded transformer would show a slanted ellipse as a result of hysterisis in the core material resulting in power loss.

A heavily loaded transformer would show a slanted ellipse with each end distorted into a tail tending to the horizontal as a result of saturation of the core material.