Description Of Operation - HBM MC3 Bedienungsanleitung

9
MC3
2

Description of Operation

Measuring amplifier MC3 is used with strain gages in a full bridge circuit or
with strain gage transducers to construct an uncomplicated and economical
measuring system.
Suitable indicating equipments for connection to this system include digital in-
dicators for switchboard installation (e.g. DA2510).
The MC3 supplies the bridge supply voltage of the transducer, amplifies the
transducer output signal and outputs a dc voltage signal of − 5 V ... 0 ... + 5V
proportional to the measured value.
A limit switch with open collector output can be adjusted over the range of
0 ... + 5 V.
When equipped with an optional final stage, an output current of
4 mA ... 20 mA is available.
Strain gages or strain gage transducers in full bridge circuit with a bridge re-
sistance of 300 ohm ... 1400 ohm may be connected. Generator G generates
a sinusoidal bridge supply voltage of 2 V (rms) with 1 kHz carrier frequency.
The connected transducer outputs a signal proportional to the measured
value when under mechanical load and this is pre−amplified in the differential
amplifier of the MC3.
The voltage necessary for balancing the transducer zero signal is added to
the measurement signal in accordance with amplitude and phase and both
are amplified depending upon the measuring range selected. Finally, the mea-
surement signal is rectified in demodulator D with the correct phase.
The output amplifier EV with low pass filter amplifies the rectified measure-
ment signal to the output level of " 5 V under the rated load of the trans-
ducer. The residual carrier voltages are suppressed to a value of < 1 %. The
measuring frequency range is 0 Hz ... 30 Hz at −1 dB (or 0 ... 65 Hz at − 3
dB).
A1705−3.2 en/de/fr
HBM