Water level measuring apparatus

Abstract

The invention relates to a water level measuring instrument, comprising: a detection electrode, a display circuit, a detection control circuit, and a power supply circuit. The control circuit includes a pulse generating circuit, a processing circuit composed of semiconductor switching tubes and a coupling circuit connected to each liquid level electrode. The coupling circuit has three heads, which are respectively connected to the output end of the pulse generating circuit and the input of the processing circuit. The terminal and one of the liquid level electrodes are connected; the return electrode is connected to the ground wire of the power supply; the pulse generating circuit sends a pulse wave with a certain duty cycle to the liquid level electrode through the coupling circuit, and the processing circuit processes the liquid level through the corresponding coupling circuit. Potential of the electrode, and send a liquid level signal to the display circuit and / or external circuit. The water level measuring instrument of the invention has wide measurement adaptability, low measurement energy consumption, little electrode corrosion and is convenient for liquid level control.

Description

【Technical field】 [0001] The invention relates to a detection and control device for water level, more specifically, the invention relates to a monitoring and adjustment device for liquid level in hydroponics. 【Background technique】 [0002] Hydroponics has been widely used in today's flowers and factory planting and cultivation. As a conductive and weakly polar liquid, water liquid plays a decisive role in the existence, development and continuation of nature and human society. It is widely used in various fields and aspects. Correspondingly, the monitoring and adjusting device of water level is also of great significance to people's social activities and development in all aspects. The technologies and equipment in this field are also complicated and diverse. These Existing technologies and equipment each have certain advantages and disadvantages. For example, float probes are widely used in many water storage containers, but the buoyancy of float probes is affected by li...

AI Technical Summary

Problems solved by technology

The shunt resistance of the device must be compensated by manually finding the probe where the scale is accumulated, and then finding the corresponding processing sub-circuit of the probe to manually adjust the shunt current. Obviously, the compensation method of the device is very backward, and in the probe The direct current flows between the electrodes, and there are still problems of large power consumption and electrode corrosion

[0005] The Chinese patent No. 94236213.6 discloses a high-precision probe with a wave-proof sleeve around the electrode for water level detection and control in an electric heating steam boiler. The protective barrier composed of the anti-wave sleeve and the cock head is provided with a damping water inlet hole on the lower end of the anti-wave sleeve. Such a structure can indeed prevent impurities in boiling water from scaling on the surface of the electrode to a certain extent, but Since fouling is also possible on the surface of the damping water inlet hole, the blocking of the damping water inlet hole will affect the measurement accuracy of the water level and the accuracy of the compensation calculation, so it is only suitable for occasions where the accuracy of the liquid level measurement is not high, and this technology The solution cannot solve the electrolytic corrosion effect of the measurement current on the metal electrode during the uninterrupted measurement process for many years, and the life of the electrode will be difficult to last; similarly, a considerable part of the electrical energy consumed by the measurement is also consumed on the electrolysis of the electrode, which will increase A lot of useless work wasted

[0006] Another example is that the document of Chinese patent 01244538.X discloses a water level detection device that adopts a single-chip microcomputer to add resistance and a probe. When the input voltage of the two probes is connected to each other due to the rise of the water level, it is equivalent to connecting a shunt resistor with a lower value in parallel between the resistor and the I / O interface 20 and 18, so that the original resistor When the voltage drops below 4 volts, a water-full signal is sent to the single-chip microcomputer; although this device uses a computer single-chip microcomputer as a detection / control circuit, it is still a direct current that flows between the two probes that go deep into the water. The consumption between the two metal probes is greater and the corresponding electrolytic corrosion still exists

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