Calrec PQ1549 resistor question
« on: June 11, 2008, 02:14:20 PM »
Does it matter if I use 1/4 watt instead of 1 watt resistors for this project? I'm pretty new at all this so I really don't know if the resistor wattage will make any difference. What, if any, difference would it make to use one wattage over another?

Thanks.
Matt


noulou

Calrec PQ1549 resistor question
« Reply #1 on: June 11, 2008, 05:22:20 PM »
1/4 watt is fine.

The difference between the two in this project is just cost and size.
You don't want either the expense or the size of the 1 watts.

Re: Calrec PQ1549 resistor question
« Reply #2 on: September 20, 2013, 03:48:22 PM »
1/4 watt 1% or 5%? Help me!

3nity

Re: Calrec PQ1549 resistor question
« Reply #3 on: September 20, 2013, 04:15:30 PM »
Whats the difference about 1% or 5%, use 10% or 20% no problem at all in my opinion.
Life is a path, death the destination.

Harpo

Re: Calrec PQ1549 resistor question
« Reply #4 on: September 20, 2013, 06:47:12 PM »
1/4 watt 1% or 5%? Help me!
Ohms law will tell you the requirements for resistors min.power rating.
Voltage will not exceed the supply rail voltages, so for DC conditions P=V^2/R. If your resistors are 1/4W and your supply rails are +/-18VDC, any resistor value with at least 1296 ohms will not exceed the 1/4W power rating for DC conditions. For resistors in the audio path assume factor SQRT(2) for RMS, so any resistor value with at least 916 ohms will not exceed the 1/4W power rating for AC conditions. All resistors in this circuit exceed these values, so 1/4W rating is sufficient, except the two 22 ohm resistors at th elast output stage, where a connected faulty/shorted xlr cable would require 0.76W rated resistors for these two parts, assuming you fit NE5532 opamps that will not deliver more than 60mA in a output shorted condition.
Allowed resistor tolerances depend on application. For frequency setting resistors, the tolerance number might be the same percentage off number for your target frequency. This might be more or less important for you. For cmrr sensitive parts of circuit (FI the 10K resistors at the balanced line receiver) you want it as close matched as possible, where same value is more important than absolute value.
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