walid Posted October 27, 2006 Report Share Posted October 27, 2006 hiin many many circuits u faced a wattage resistance for example in a PC monitor i see a 1 ohm 5 watt and in a low cost inverter in our project section you can see a 6 0.5 ohm 10 wattalso in many car batt charger you find one directly before the battwhy this resistancecan i replace it with a thick long wirethanx Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 27, 2006 Report Share Posted October 27, 2006 Hi Walid,Power resistors are much smaller and cost much less than 0.5 ohm or 1 ohm of long wire.Copper wire increases its resistance with heat, most power resistors don't. Quote Link to comment Share on other sites More sharing options...
walid Posted October 27, 2006 Author Report Share Posted October 27, 2006 hi guruwe all know that resistors are used to limit current to some valuecan a 0.5 ohm resistor limit current and to what levelsecondly: why it so big 10 watt, what if i use a 0.5 watt regular resitorsno no, i'll ask my question another way:what exactly i want to know that: what should i think when i see say 0.5 ohm 10 watt resistor in any boardMY ANSWER:power = I*I*R10 watt = I*I*0.5 I max= 4.5amperso i shoud expect that this R can safely pass a 4 A of currentis it true guruthank u guru Quote Link to comment Share on other sites More sharing options...
audioguru Posted October 27, 2006 Report Share Posted October 27, 2006 Hi Walid,I never use resistors at their power rating. Look at their datasheet, the temperature is hundreds of degrees C at the rated power. Their power rating is "the absolute max do not ever exceed" amount.Power resistors are big and take time to heat up. So they can pass pulses of current much higher than they can pass continuously. Quote Link to comment Share on other sites More sharing options...
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