David Wrigley's Microwave Website, Manchester, England

Useful Information - Magnetics

Under construction

Transformers
Transformers rely on Steel Laminations for their magnetic coupling. The Primary winding is designed to magnetize the steel to a design level of flux (the designed Turns per Volt value will achieve this). Generally the core flux is set at a level where the losses are acceptable - ie before too much saturation occurs. The overall design is a compromise between copper (winding) losses and iron (core) losses and the final design will depend on how the transformer is intended to be loaded.

Steps in the design of a transformer.

Establish range of supply voltage and frequency
Establish secondary load(s)
Determine overall VA required
Determine size of core (winding window area)
Determine TPV for core and losses
calculate turns and insulation for all windings
add winding allowances
check winding CSA against winding window area
adjust for optimum losses
Wind Bobbin and assemble core
Test for insulation,output voltage,regulation and temperature rise

Use of Maplin Cores with prewound primary as replacement transformer
Example - a multi secondary transformer to fit the Trio CS-1830 Oscilloscope

Ferrites
Available range of Ferrites

Iron Dust Cores
Differences between Ferrites and Iron Dust

Simple Core testing- using a short pulse and an oscilloscope to check the resonant frequency of a test winding