Electronic weighing scale

摘要

It is known in high-resolution electronic weighing scales based on the principle of electromagnetic force compensation that the load-dependent development of heat in the coil and the precision resistor can be compensated by sending an additional alternating current through the coil and the precision resistor which is complementarily regulated in its amplitude. In order to make possible a precise regulation of the amplitude of the additional alternating current even in the case of a small carrying force of the electromagnetic force compensation and of a correspondingly small direct compensating current, the invention proposes connecting in a voltage divider in parallel to the coil and the precision resistor which has a highly temperature-dependent resistor. In this parallel branch direct and alternating current are higher by a constant proportionality factor than in the main branch formed by coil and precision resistor. The parallel branch is also part of a resistance measuring bridge which regulates the amplitude of the additional alternating current in such a manner that the highly temperature-dependent resistor retains its theoretical excess temperature and therewith its theoretical resistance value.