My CTC-16XL Project.

[tubesrule]

Tom
You just repeated what I said. Wattage rating has nothing to do with terminal temperature. Thermal resistance does. For example, modern metal film 1W and 2W resistors are smaller than older 1/2W carbon comp resistors because they are designed to run hotter (better materials) and do run hotter because they are smaller (higher thermal resistance). So in this case, a physically smaller resistor is a better choice for reliability even though it will run hotter at the same power dissipation as the larger 1/2W comp resistor.
If you want to state that a higher wattage resistor that is the same composition and much larger in physical size will run cooler, that is a true statement, but only because its thermal resistance is lower, not because its wattage is higher. The two are not absolutely related or interchangeable.

[Electronic M]

Originally Posted by tubesrule

Tom
You just repeated what I said. Wattage rating has nothing to do with terminal temperature. Thermal resistance does. For example, modern metal film 1W and 2W resistors are smaller than older 1/2W carbon comp resistors because they are designed to run hotter (better materials) and do run hotter because they are smaller (higher thermal resistance). So in this case, a physically smaller resistor is a better choice for reliability even though it will run hotter at the same power dissipation as the larger 1/2W comp resistor.
If you want to state that a higher wattage resistor that is the same composition and much larger in physical size will run cooler, that is a true statement, but only because its thermal resistance is lower, not because its wattage is higher. The two are not absolutely related or interchangeable.

I was never trying to say that 2 different composition parts will have the same thermal resistance for a given wattage rating when you started arguing. Merely stating that if you are going with some wattage in a given composition part that choosing a higher one than necessary tends to reduce case temperature...You're very passionate about arguing an accurate generalization deep into the weeds.

[tubesrule]

I was responding to your original comment which was inaccurate and who's goal posts have now been moved several times. Sorry I wasted time on the forum. It won't happen again. Carry on.