david90 said:I have a circuit that uses a resistor to drop the input voltage. From my calculation, the power dissipation thru the resistor is less than it's wattage rating but yet the resistor is hot to the touch. Should I use a bigger resistor because it's too hot to the touch or should I keep using it because the power dissipation is within spec? The resistor is the ceramic wire wound type.
The general rule of thumb is to select a power resistor whose power rating is at least double the power it will be expected to handle.Note that the nominal power rating of a resistor is not the same as the power that it can safely dissipate in practical use. Air circulation and proximity to a circuit board, ambient temperature, and other factors can reduce acceptable dissipation significantly. Rated power dissipation may be given for an ambient temperature of 25 °C in free air. Inside an equipment case at 60 °C, rated dissipation will be significantly less; if we are dissipating a bit less than the maximum figure given by the manufacturer we may still be outside the safe operating area, and courting premature failure.
A resistor is an electrical component that is used to limit the flow of current in a circuit. It is often used to control the voltage and current levels in a circuit, and to protect other components from damage.
The wattage rating of a resistor is typically indicated by a number followed by the letter "W" (e.g. 1W, 5W, etc.). To determine the wattage rating, you will need to know the voltage and current values in your circuit. Using the formula P=VI (power equals voltage multiplied by current), you can calculate the required wattage rating for your resistor.
If a resistor with a lower wattage rating is used, it may not be able to handle the amount of power in the circuit and can overheat and potentially fail. This can lead to damage to other components in the circuit and potentially cause a fire hazard.
You will need a bigger resistor if the wattage rating of your current resistor is not high enough to handle the power in your circuit. This can be determined by calculating the power in your circuit and comparing it to the wattage rating of your current resistor. If the power is higher than the wattage rating, you will need a bigger resistor.
Yes, there are other factors to consider such as the operating temperature, ambient temperature, and the expected lifespan of the resistor. It is important to choose a resistor with a wattage rating that can handle the power in your circuit, as well as any other potential factors that may affect its performance.