SU396561A1 - SCHEME OF EQUALIZING THE MEASURING BRIDGE - Google Patents

Description

one

The invention relates to the field of instrumentation and can be used to measure the level of liquids.

Known digital capacitive level gauges containing a bridge circuit and an extreme type equilibration device do not provide sufficient accuracy, since the least significant bit that is in a state of continuous oscillations is not connected to a digital reading device.

In order to increase the level measurement accuracy in the proposed circuit, a counter-meter is connected to the register through the circuits AND, the control inputs of which are connected to the pulse amplifiers.

The drawing shows the balancing scheme of the measuring bridge of a diffractive capacitive level gauge.

The circuit contains a working sensor /, two compensation sensors, a measuring bridge circuit 4 with a linear-decoding converter as an adjustable element, a generator 5 supplying the measuring circuit 4, to the output of which amplifier 6 is connected. The output of the amplifier is connected to the input of the amplitude detector 7, and the output of the amplitude detector through an amplifier of 8-positive pulses - to trigger 9 and through an amplifier 10 negative pulses to the control input of the “And 11” circuits, whose inputs

connected to the balancing counter 12, and the outputs to the register 13. Paraphase outputs of the trigger 9 are connected to the circuits And 14, 15, the second input of which is connected to the output of the generator 16 control pulses, and the outputs of the circuits And 14 and 15 to the inputs of the balancing counter 12 corresponding to the direct and reverse directions of equilibration.

The balancing scheme of the measuring bridge of the digital capacitive level gauge works as follows.

When the level changes depending on the state of the trigger P at the output of one of the circuits

"And 14 and 15 appear pulses coming from generator 16 to the corresponding input of the counter meter 12. With the wrong direction, the balancing envelope of the output voltage, extracted by the amplitude detector 7, is a positive pulse that, having passed through the amplifier 8, flips trigger and rebalances direction. When approaching the measuring bridge circuit

4 to the equilibrium state, the amplitude detector 7 selects a negative pulse of the envelope, which, having passed through amplifier 10, opens an AND circuit, and the code from counterbalance counter 12 is rewritten to

register 13.

Subject invention

A balancing circuit for a measuring bridge, a nairnmer, a digital capacitive level gauge, comprising an amplifier, an amilite detector, pulse amplifiers, a register, a balancing counter with a control circuit, an AND circuit, which, in order to achieve an increase in level measurement accuracy, a counter meter and a circuit, and a control circuit. through the circuits “And, the inputs of which are the switches and switches to the pulse amplifiers.