Carroll & Meynell variable autotransformers have variable voltages and are ideal for controlling AC voltages. The rotating arm with a carbon brush changes the output voltage.
These variacs feature round carbon brushes, riding any imperfections, offering a smoother operation. The round carbon brushes last the lifetime of the unit and are more robust than standard rectangular brushes, which are susceptible to breakages. These variacs have high efficiency and excellent regulation with no waveform distortion.

A round carbon brush offers low current density
Low magnetising current
Robust construction
Low operating torque
Smooth output and linear output
Centre tap in winding for buck–boost applications

Variable Auto Transformers

Continuously variable alternating current (a.c.) output voltage
Rugged construction
Low operating torque
High efficiency/excellent regulation

Silver-plated commutator
Low magnetising current
No waveform distortion, smooth linear output & overload capacity
Screw terminals
Complete with knob and dial