Quote:
Originally Posted by Phil Nelson
What's in those attenutators, exactly, besides a potentiometer? I have a similar looking Radio Shack model. Got it at a garage sale for a nickel or something. Maybe it's defective. I tried it a couple of times, and it seemed to have a range between distorting the signal and really really really distorting the signal.
Phil
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If it is properly designed, a "T-pad". This is similar to the "L-pad" used for speaker-level volume controls but it has three ganged potentiometers instead of two.
The stem of the T is a potentiometer to ground and the arms go to source and load.
An L-pad presents a constant impedance to the source and variable to the load (assuming that the source and load impedance are correct).
A T-pad presents a constant impedance to both the source and load (with the same underlying assumption).
Switched attenuators are really stepped T-pads.