Can someone explain the statement regarding the green resistor. I understand the red being the DC resistance of the inductor, but what is meant by "subtract inductor resistance to get actual required resistance"? Why is this one different from the other inductors? Thanks, Kev
In the end it isn't actually different.
The resistance of the inductor and the resistor add together. This means you can use an inductor with a much higher resistance and get the same effect by simply reducing the value of the resistor by the right amount.
This means that it is unnecessary to use a very low resistance inductor in this position, and due to size, parasitics and cost it may sometimes be better to avoid a very low resistance inductor. On the other hand, when you use a high resistance inductor you need to consider the heat that may be produced.
The resistance of the inductor and the resistor add together. This means you can use an inductor with a much higher resistance and get the same effect by simply reducing the value of the resistor by the right amount.
This means that it is unnecessary to use a very low resistance inductor in this position, and due to size, parasitics and cost it may sometimes be better to avoid a very low resistance inductor. On the other hand, when you use a high resistance inductor you need to consider the heat that may be produced.
R7 is a needed physical resistor that is significantly larger in value than an inductor resistance.
The L5, C5, and R7 make a tuned circuit (notch filter), with a minimum impedance set by
the actual value of R7 plus the smaller L5 resistance.
The other inductors form part of a LP or HP filter, where a series resistor with the inductor is not useful.
The L5, C5, and R7 make a tuned circuit (notch filter), with a minimum impedance set by
the actual value of R7 plus the smaller L5 resistance.
The other inductors form part of a LP or HP filter, where a series resistor with the inductor is not useful.
The total resistance off L6 and R7 is 4.7 Ohms. For example, if the resistance of L6 is 1.0 Ohms then use 3.7 Ohms for R7.