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4.1.1 Galvanic Isolation
The supply voltage of the amplifier is galvanically isolated from analogue output, sensor supply and
sensor signal. To unset this isolation, clamp 3 and 4 have to be bridged.
4.2 Strain gauge excitation voltage
The described measuring amplifier is able to supply one or two strain gauge transducer. Any strain
gauge full bridge with a bridge resistance of 300 ohms or more may be connected. The transducer can
be supplied with a bipolar voltage of either ± 5 V (= 10 V) or ± 2,5 V (= 5 V). This value can be selected
by internal DIP-switches and with 2 potentiometers for fine adjustment.
DIP switch S-101/S102 on Althen 73
1
2
Strain gauge feeding voltage
ON
OFF
±5 Volt (=10 Volt)
OFF
ON
±2,5 Volt (=5 Volt)
4.2.1 Connection in 4- or 6-wire technology.
The described measuring amplifier allows to connect the transducer in either 4-or 6-wire technology.
The excitation voltage received by the sensor has great influence on the sensor signal. So, if, with a
very long cable, or by lengthening of it, the excitation voltage drops even by a slight value, the signal
drops accordingly. If the amplifier together with the sensor has been factory calibrated, a longer cable
should pose no problem. But if the cable is shortened or lengthened after calibration the calibration will
void.
It is preferred to connect the sensor in 6-wire technology, if the cable is to be lengthened, because the
2 additional wired measure the excitation voltage directly at the sensor and the amplifier adjusts the
exc. voltage accordingly.
DIP-switch S-101, S-102
Potentiometer fine adjustment
