Liquid meter - how much wine in a tank ?

Device measures the amount of liquid in a cylindrical tank. The tank must be of equal cross section in length, and fixed in vertical or horizontal position. Four tank sizes (diameter and height) are selectable by switch.

Measurement is based on the HC-SR04 ultrasound sensor, this measures the distance of the liquid surface from the opening on top of the tank. Subtracting the neck height from the distance measured, we can use formulas to calculate how much liquid is left in the tank. To increase accuracy, the average of 10 measurements is used. Display is refreshed once per second.

The device is plugged directly in a power bank's USB, which serves as a handle as well. Use a lanyard to prevent dropping it into the tank...

The 3D box holds the 0.96" OLED display, the sensor and Arduino Atmega328 Mini or ESP8266 D1 Mini together. USB-A PCB in a rigid mount supplies the power.

Arduino program : i2c OLED (address 0x3c or 0x3d) on A4 A5, Trig on 2, Echo on 13 pin. The tank diameter arrays in my example are wine storage vessels from an Italian manufacturer. Replace it with your data. Select tank position horizontal / vertical when compiling. Switch is SP4T type with 3 resistor voltage divider to A0 analog input. The ESP D1 Mini's USB is accessible so the program - for example new cylinder data - can be refreshed any time, which is not the case with the Arduino (AVR) mini.

The display shows the amount in liters, and a tank drawing striped to amount or a moving scale. If you don't need the drawing but only a clear display of liters, uncomment the program line at the end of main loop.

The ESP seems to be 5V tolerant, but it does not hurt to use 2.2k + 3.3k level shifter resistors on the Echo input (13).

Using the device : accuracy depends only on the sensor, so hold it steady and levelled when measuring. Experience shows pretty good results measuring the amount of wine in storage tanks.

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