Dimmer Dot
Variable Auto Transformers
C – Tick approved
Tested in Australia by a
NATA accredited laboratory
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Dimmer Dot is a variable auto transformer which provides continuously adjustable AC voltage. In it’s “Auto transformer” form it is an efficient, reliable method of controlling AC voltage from zero to line voltage by amplitude modulation of the AC waveform. Since the current, power, heat, light and motor speed are further functions of the voltage, the Dimmer Dot Variable Transformer finds its varied use, but is not designed to provide AC mains isolation.

Dimmer Dot Variable Transformer, consists of a single-layer winding on a toroidial silicon-steel core. As the control knob is rotated, a carbon brush traverses the winding, tapping off a portion of the total voltage across the winding. The brush is in continuous contact with the winding, and the voltage between turns is always less than 1 volt even in the largest model. In the smallest model it is only about 0.3 volt. The discrete voltage increments obtained as the knob is rotated are always less than the voltage between turns. Since the brush spans more than one turn, the change in voltage is practically continuous. The brush is so designed that excessive heating cannot occur in the turns that it spans.
Dimmer Dot has many operating advantages over any other manually operated voltage control devices for alternating current use.

Good Regulation
Output voltage is substantially independent of load.
Smooth Control
The Dimmer Dot can be set very closely to any output voltage within its range.
High Efficiency
Very low losses under all load conditions. Greater than 96% efficient.
Long Life
With the exclusive Dura Dot contact surfaces, the life of the Dimmer Dot Variable Auto Transformer is essentially the same as that of any standard fixed-ratio power transformer.
Linear Output Voltage
Output voltage is continuously adjustable from 0-112% of line by approximately 340°. The dial reads directly in no-load output voltage at rated line voltage or some dials are calibrated for percentage of the full range control.
Mechanical Design
Rugged construction and robust parts. Two or more units can be ganged on same shaft. Shaft is also reversible for simple conversion from front to back of panel mounting.
High ambient temperature tolerence. Current rating up to 45°C
Sine Wave Purity
Virtually no radio interference, wave shape distortion or harmonics created, unlike SCR-Thyristor and Triac AC power controllers.
Lower Input Current
Input power consumption is proportional to output unlike electronic Thyristor controllers which still maintain high input RMS currents.
Special Voltage Range
Dimmer Dot is available in standard Single phase 240 V and Three phase 415 V 50 Hz. Other special input voltages can be supplied.
Two phase models are also available
Technical Assistance
Our engineers are well qualified to advise and assist you with the selection and applications on Dimmer Dot Variable Transformers
Twelve months from date of purchase

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