Calculations

Calculations

Increasing Resistance

The wattage rating is how much energy the resistor can absorb and dissipate.

It is more important to have an accurate Ohm rating for your resistor than it is the wattage.

Resistors are solid state components that have a fixed internal resistance that cannot be altered which is listed as their resistance rating. The amount of circuit amperes they can handle is listed as their wattage rating.

While resistors are useful, I prefer rheostats because you are able to control the resistance of your circuit with the turn of a dial. With this ability you gain control of the circuit’s current flow (and temperature) when the voltage from the power supply cannot be altered. Visit the Fixed Voltage Power Section for more information on this topic as many concepts overlap.

When dealing with resistors and rheostats, there are a few points to keep in mind...

Consider the Wattage rating is a minimum,

and the Ohm rating is a maximum.

Brown, Yellow, Red, Grey

14 x 10 ohms

2

1400 ohms

or

Black, Green, Brown, Grey

05 x 10 ohms

1

50 ohms

or

Grey, Blue, Orange, Red

86 x 10 ohms

3

86k ohms

or

+/- 0.05%

+/- 0.05%

+/- 0.05%

+/- 0.05%

+/- 2.0%

+/- 2.0%