To design a simple submerged level meter circuit, you can follow these steps:
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Sensor Selection:
- Choose two conductive probes as the sensors. The length of the probes should be determined based on the desired liquid level range to be detected.
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Power Supply:
- Select an appropriate DC power supply, such as 5V or 12V.
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Comparator Circuit:
- Use a comparator chip, like the LM393.
- Connect a fixed reference voltage to one input of the comparator. This reference voltage can be obtained from the power supply through voltage divider resistors and adjusted according to the liquid level detection point you desire.
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Sensor Connection:
- Connect the two probes to the other input of the comparator and ground respectively.
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Output Indication:
- The output of the comparator can be connected to an LED indicator or a buzzer. When the probes come into contact with the water, the resistance changes, and the output state of the comparator changes, causing the indicator light to turn on or the buzzer to sound, indicating that the liquid level has reached the detection point.
For example, suppose you want to trigger an indication when the liquid level reaches half the length of the probes. You can use two resistors (such as 10kΩ and 20kΩ) connected in series to obtain approximately 1/3 of the supply voltage from the power supply as the reference voltage and connect it to one input of the comparator. When the water touches the probes, the voltage at the input of the comparator is lower than the reference voltage, and the comparator outputs a high level, turning on the LED.
Please note that this simple circuit may require further optimization and protective measures in practical applications to improve stability and reliability.