Although the current hopper scale also has a printer interface, the printer printing weighing results, temperature, humidity, vibration, air cleanliness and other environmental conditions are almost all very high requirements. Once it does not meet the requirements, it will not work properly or often malfunction. However, the charging system of some small blast furnaces does not have the above environmental conditions.

Actual picture of hopper scale

When the DC millivolt weighing signal output by the sensor is sent to the electronic hopper scale display screen, it will also be sent to the automatic balance recorder to automatically record the weighing result. Because the automatic balance recorder will automatically generate the bridge unbalance voltage consistent with the input signal, so as to achieve the automatic balance with the input signal. The current in the input circuit is zero, so it will not consume the weighing signal itself, nor affect the accuracy of the weighing result. In the figure, the stabilized power supply composed of bridge rectifier, Zener diode and potentiometer is a zeroing circuit, and the output voltage is stable at 010 MV.

Hopper scale When the supply voltage change is 10% of the rated value, the output voltage change is less than 0.05%. Its function is to subtract the output signal of the sensor, eliminate the zero deviation of the sensor itself, eliminate the weight and tare weight of the scale. R3 is a steel resistance controlled by a thin copper wire. Its function is to eliminate the influence of voltage temperature coefficient of voltage regulator D3. w should use multi-turn potentiometer to achieve the purpose of fine tuning.