HBM ME30, Operating Manual

Page: 16 / 28

16
ME 30
4.4 Bridge Fine Balancing
a) Coarse Balancing
The 16-stage switch S22 is used for the coarse balancing carried out from the
front panel; the polarity of the balancing direction can be chosen via switch
S23. The overall balancing range is approximatly
±
2mV/V.
b) Fine Balancing
The potentiometer P23 is used for the fine balancing (
±
0.08mV/V).
c) External Zero Balancing
A balance range of
±
0.12mV/V set by the manufacturer can be passed with
an externally connected potentiometer of 50 k
Ω
Pin assignment:
potentiometer pin 26c . . . . . . . . . . . . .
wiper pin 21c . . . . . . . . . . . . . . . . . . . .
potentiometer finish pin 24c . . . . . . . .
4.5 Calibration signal
Switching switch S21 to the right (calibration) detunes the amplifier by a de-
fined amount (=+1mV/V). The measuring range can be adjusted without hav-
ing to load the connected transducer respectively. The voltage at the amplifier
output which is equal to the calibration signal is added to an available voltage,
if any (additive calibration signal)
R=50k
Ω