At 24V, P = V^2/R = (24)^2/10 = 576/10 = 57.6W. Too much power through the resistor.I have a 10 ohm 25W resistor that smells like its burning. The applied voltage is between 12V & 24V Ac or DC. The resistor still measured out @ 10 ohm after the smell of burning. What happening?
The wattage rating on a resistor and that on an incandescent lamp are two different things. A lamp will have a specific voltage rating, and the wattage is the power it will consume at that voltage. The power rating on a resistor is the maximum power it can handle, and you must calculate at what voltage that limit will be reached. For a 10 ohm 25 watt resistor, V^2/10 = 25, V = sqrt(250) = 15.81V. That's why it smells funny at 24V.Is the wattage rating on the resistor the same as the rating of wattage on an incandescent lamp? The lamp will have a voltage rating, the resistor does not have voltage stamped on it. I take it, regardless of absence of voltage rating on resistor that calculations need to be performed.
I have a 10 ohm 25W resistor that smells like its burning. The applied voltage is between 12V & 24V Ac or DC. The resistor still measured out @ 10 ohm after the smell of burning. What happening?
What is the ratio of hours to years? (Seriously)Incandescent bulbs at rating are usually in the ballpark of 1000 hours. But there are some that operate at a lower temperature that may be 5000 hours, and others at an even lower temperature may have a 50,000 hour rating... A power resistor might be in the 10 to 50 year range at rated power.
Well, yeah.I think we all agree that the reason the resistor smells like it is burning up is that the resistor is, in fact, burning up.
I could have done the math. :roll:There are approximately 365.25 days per year. This is without the 400 year correction. Thus, hours per average year is 8766 and 10 years is 87,660 hours and 50 is 438,300 hours. Average is done over 4 years. Three non-leap-years and one leap-year.
I believe that the 1000 hour quoted life is the time for 50% of the bulbs to fail...Also the design life of different devices likely will be different. Incandescent bulbs at rating are usually in the ballpark of 1000 hours.
Years ago, when my son was little, I connected a diode across the hall bathroom light switch, so it was bright/dim instead of on/off, and was a great nightlight, too.I use a 757 at 12 V in our bathroom as a night light and never have to change the bulb. Even though it is a small bulb and operated at somewhat less than half voltage it is adequate light.