This selection or trimming only requires comparing the resistances of two resistors in each trimming step, which is easily accomplished by using a Wheatstone bridge circuit and a sensitive null detector a galvanometer in the 19th century, or an electronically amplified instrument today.
22.
In power supply design, a bridge circuit or bridge rectifier is an arrangement of diodes or similar devices used to rectify an electric current, i . e . to convert it from an unknown or alternating polarity to a direct current of known polarity.
23.
On the other hand, if generators are connected to pole pairs ( 1, 4 ) and ( 2, 3 ) then those pairs are ports, the pairs ( 1, 2 ) and ( 3, 4 ) are no longer ports, and the circuit is a bridge circuit.
24.
Properly designed, a bridge circuit can be used not only to indicate a match, but the degree of mismatch-thus making it possible to calculate the SWR . This usually involves alternately connecting the reference wave and the reflected wave to a power meter, and comparing the magnitudes of the resulting deflections.
