eTape - water level sensor

Measure the level of water (30cm Max)

This eTape sensor is a solid sensor measuring the water level by using a resistive principle. Indeed, the tape resistance is a factor of the height of the liquid touching it.

Thank to this sensor, not need to use a float anymore and it can also be wired quite easily on electronic project.

The eTape sensor is sitted into a protective shell allowing the liquide to penetrate the shell but still protect the sensor (it can be easily damaged).

The core of the eTape is compressed by the fluide (the hydrostatic pressure) which modifies the resistor of the eTape band. The resistor varies with the height of the fluide. Please, note that resistance is proportionnaly inverted regarding the height of the liquid: lower is the fluide, higer is the resistor.

This sensor is unique and stays pretty affiordable for a sensor able to measure fluide height with some precision. Reading offers great precision and are repetitives.

The eTape sensor made 30 cm height and is fitted with 3 pins JST connector.

Thanks to the resistive technology, this sensor is quite easy to read with a analog to numeric converter (ADC) as found on Arduino and other MicroControler. See the example here under.

Technical details

• Size: 305mm x 29mm x 13mm
• Weight: 56g
• Output resistor: 400-2000Ω ±20%
• Reference resistor: 2000Ω ±20%
• Minimal water level (activation level): Nominal 25.4mm
• Resistor gradiant: 60Ω/cm
• Maw power: 0.5 Watts (estimated).
  Adapt the circuit voltage to stay under 0.5W otherwise the sensor with deteriorate. P = R x I^2
• Working temp: -9°C - 65°C
• eTape technical datasheet (pdf)

How to use

Connect the pin #2 to the ground/GND, then the pin to a 560 ohms resistor. The other end of the 560 ohms resistor must be connected to VCC (3.3V or 5V depending on the loclic level of your MicroControler). So we do have a resitor voltage divider.
The analog input of the microcontroler is connected at the junction between the eTape and the 560 Ohms resistor.

// Value of the fixed resistor
#define SERIESRESISTOR 560    
 
// Pin connected to the sensor
#define SENSORPIN A0 
 
void setup(void) {
  Serial.begin(9600);
}
 
void loop(void) {
  float reading;
 
  reading = analogRead(SENSORPIN);
 
  Serial.print("Analog read "); 
  Serial.println(reading);
 
  // Convert reading to resistor
  reading = (1023 / reading)  - 1;
  reading = SERIESRESISTOR / reading;
  Serial.print("Sensor resistor "); 
  Serial.println(reading);
 
  delay(1000);
}