Discount Electronic Components
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 DIA | WATTAGE | MODEL | DIAMETER | RESISTANCE 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.