The amplifier output is rectified by shunt diode MRl and fed to the
meter, so that the meter always deflects to one side of zero far alI a. c.
measurements. Two germanium diodes MR2 and MR3 are connectedacross
the meter as limiters to protect it tram severe overloads. For d.c. resis-
tance measurements the unbalanced output tram the bridge is applied directly
to the meter so that now it deflects either side of zero, passing through zero
at the balance nullo
Note:
Because the detector is unselective, pickup of strayfields inaccessories
such as the D. C. Choke Adaptor, TM 6113, can result in a standing reading
on the meter. 1£ this problem is not surmountable by moving the bridge and
adaptor to another location, an oscilloscope or selective device can be used
as an external detector so that the null can be easily found.
30 2700 (la)
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