14-04-2014, 01:19 PM
Richard - just to be quite sure that you fully understand this matter of 'wattage' when it comes to resistors: here's an analogy.
Consider a car engine. It is designed to have a maximum speed of, say, 10,000 r.p.m. Now you can drive that car at any speed you like - just so long as the engine speed doesn't exceed 10,000 r.p.m. The stated wattage rating of a resistor is equivalent to the maximum r.p.m. of that car engine. The actual power the resistor will dissipate is the equivalent to the speed the engine actually runs at. So the objective is to always keep the engine r.p.m. less than the maximum r.p.m.; the power actually dissipated in the resistor must always be less than the maximum power the resistor is designed to dissipate - this is the stated wattage rating of that resistor.
Like lots of things in life, there is a safe limit as to how hard you can 'push' something: the stated wattage tells you that. But if you exceed that figure - trouble!
Al.
Consider a car engine. It is designed to have a maximum speed of, say, 10,000 r.p.m. Now you can drive that car at any speed you like - just so long as the engine speed doesn't exceed 10,000 r.p.m. The stated wattage rating of a resistor is equivalent to the maximum r.p.m. of that car engine. The actual power the resistor will dissipate is the equivalent to the speed the engine actually runs at. So the objective is to always keep the engine r.p.m. less than the maximum r.p.m.; the power actually dissipated in the resistor must always be less than the maximum power the resistor is designed to dissipate - this is the stated wattage rating of that resistor.
Like lots of things in life, there is a safe limit as to how hard you can 'push' something: the stated wattage tells you that. But if you exceed that figure - trouble!
Al.
