
11 8
Analog Electronics
operated toggle switches, or might be operated in
sequence as required by cams on a shaft to provide
rotary knob operation. The electrical design would
be such as to ensure that with OdB selected, the
internal wiring exhibited throughout a character-
istic impedance
Z o
equal to /?,), usually 50 Ω.
Another use for pads is to enable accurate
measurements to be made where two different
impedance levels are concerned, without errors
(or the necessity for corrections) for mismatch
losses. For example, one might want to measure
the gain at various frequencies of an amplifier with
75 Ω input and output impedances, using 50