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Electronic Components - Rheostats.

What are Rheostats?

A rheostat is an electronic device that can adjust resistance in a circuit. A rheostat can be used as a potentiometer to divide resistance.

To select a rheostat, one should know the maximum resistance. Then, one should select the maximum voltage. Then, determine the rheostat's wattage:

P = V2 / R

  • P - power
  • V - voltage
  • R - resistance

The rheostat is constructed using ceramic material.

The 12.5 Watt rheostat is good for power ratings between 1 Watt and as high as 12.5 Watt. These extremely small rheostats 7/8" are high quality at a size smaller than a standard 2 Watt potentiometer. The shaft is 1/8" diameter.

TEDSS.com stocks rheostats from 12 ½ Watt through to 1000 Watt.

The attached chart shows the Wattages, Unit Diameter, and the Ohmage Range.

SHAFT DIAWATTAGEMODELDIAMETERRESISTANCE RANGE
(inch) (watt) (inch) (ohms)
1/8 12.5 E 7/8 1 ohm - 5 Kohm
1/4 25 H 1 9/16 1 ohm - 5 Kohm
1/4 50 J 2 5/16 0.5 ohm - 10 Kohm
1/4 75 G 2 3/4 0.5 ohm - 10 Kohm
1/4 100 K 3 1/8 0.5 ohm - 10 Kohm
1/4 150 L 4 0.5 ohm - 10 Kohm
3/8 225 P 5 1 ohm - 2.5 Kohm
3/8 300 N 6 1 ohm - 2.5 Kohm
3/8 500 R 8 1 ohm - 2.5 Kohm
3/8 750 T 10 1 ohm - 2.5 Kohm
3/8 1000 U 12 1 ohm - 2.5 Kohm

Rheostats from 12.5 Watt - 150 Watt can come with a shaft for a knob, or a 1/2 inch locking bushing with a screw driver adjust shaft.

Models of 225 Watt through 1000 Watt have a shaft of 3/8 inch diameter. These shafts are usually flatted to make a tight fit for a knob.

The typical rheostat is linear in taper.

At TEDSS.com you will also find rheostats that can be adjusted to an OFF position.

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