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--- en:iot-open:hardware2:sensors_electric [2024/05/23 22:44] – pczekalski
+++ en:iot-open:hardware2:sensors_electric [2024/05/27 14:58] (current) – ktokarz
@@ Line 1: / Line 1: @@
+====== Electrical Characteristic Sensors ======
+{{:en:iot-open:czapka_b.png?50| General audience classification icon }}{{:en:iot-open:czapka_e.png?50| General audience classification icon }}\\
+Electrical characteristic sensors measure the voltage and amperage of the electric current. When the voltage and current sensors are used concurrently, the device's consumed power can be determined. Electrical characteristic sensors can also determine whether the device's circuit is working correctly. Different sensor circuits must be used to measure direct current (DC) and alternating current (AC). For safety reasons, the parameters of the mains must be measured using transformers.
+== Potentiometer ==
+A potentiometer is a type of resistor whose resistance can be adjusted using a mechanical lever. The device consists of three terminals. The resistor between the first and the third terminal has a fixed value, but the second terminal is connected to the lever. Whenever the lever is turned, a slider of the resistor is moved; it changes the resistance between the second terminal and side terminals. Variable resistance causes the change of the voltage, which can be measured to determine the position of the lever. Thus, the potentiometer output is an analogue value.\\
+Potentiometers are commonly used as a control level, for example, a volume level for the sound and joystick position. They can also be used to determine the angle in feedback loops with motors, such as servo motors. The potentiometer symbol is present in figure {{ref>potentiometer1}}, a device in figure {{ref>potentiometer2}} and a connection to the Arduino board in figure {{ref>potentiometer3}}.
+<figure potentiometer1>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:potentiometer_symbol_europe.png?100 | Symbol of a potentiometer}}
+<caption>A symbol of a potentiometer</caption>
+</figure>
+<figure potentiometer2>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:potentiometer_c.jpg?200 | Potentiometer}}
+<caption>A potentiometer</caption>
+</figure>
+<figure potentiometer3>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:sch_apz_shemas_potentiometer.png?200 | Arduino and potentiometer circuit}}
+<caption>Arduino and potentiometer circuit</caption>
+</figure>
+An example code:
+<code c>
+//Potentiometer sensor output is connected to the analogue A0 pin
+int potentioPin = A0;
+//The analogue reading from the potentiometer output
+int potentioReading;
+void setup(void) {
+  //Begin serial communication
+  Serial.begin(9600);
+  //Initialize the potentiometer analogue pin as an input
+  pinMode(potentioPin, INPUT);
+}
+void loop(void) {
+  //Read the analogue value of the potentiometer sensor
+  potentioReading = analogRead(potentioPin);
+  Serial.print("Potentiometer reading = "); //Print out
+  Serial.println(potentioReading);
+  delay(10);
+}
+</code>
+== Voltage Sensor ==
+A voltage sensor is a device or circuit for voltage measurement. A simple DC (direct current) voltage sensor consists of a voltage divider circuit with an optional amplifier for a tiny voltage measure. For measuring the AC (alternating current), the input is connected to the rectifier diode or bridge to rectify AC to DC and a capacitor to flatten the voltage. The resulting voltage can be measured with an analogue digital converter of the microcontroller. For safety, while measuring the mains voltage, an optoelectrical isolator should be added at the output, or a transformer should lower the voltage at the input.\\
+A voltage sensor can detect a power failure and measure if the voltage is in the range required. IoT applications include monitoring appliances, power lines, and power supplies.\\
+Sample voltage sensor module is present in figure {{ref>sensor_voltage1}} and schematic connection to the Arduino Uno in figure {{ref>sensor_voltage2}}.
+<figure sensor_voltage1>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:voltage_senor_c.jpg?200 | Voltage sensor module 0–25 V}}
+<caption>Voltage sensor module 0–25 V</caption>
+</figure>
+<figure sensor_voltage2>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:voltage_sen_sch_hd.jpg?400  | Arduino and voltage sensor schematics}}
+<caption>Arduino and voltage sensor schematics</caption>
+</figure>
+The example code:
+<code c>
+//Define an analogue A1 pin for voltage sensor
+int voltagePin = A1;
+//The result of the analogue reading from the voltage sensor
+int voltageReading;
+float vout = 0.0;
+float vin = 0.0;
+float R1 = 30000.0; //  30 kΩ resistor
+float R2 = 7500.0; //  7.5 kΩ resistor
+void setup()
+{
+    //Begin serial communication
+    Serial.begin(9600);
+    //Initialize the analogue pin as an input
+    pinMode(voltagePin, INPUT);
+}
+void loop()
+{
+    //Read the value of the voltage sensor
+    voltageReading = analogRead(voltagePin);
+    vout = (voltageReading * 5.0) / 1024.0;
+    vin = vout / (R2/(R1+R2));
+    Serial.print("Voltage is: ");
+    //Print out the value of the voltage to the serial monitor
+    Serial.println(vin);
+    delay(10); //Short delay
+}
+</code>
+== Current Sensor ==
+A current sensor is a device or a circuit for current measurement. A simple DC sensor consists of a high-power resistor with low resistance. The current value is obtained by measuring the voltage on the resistor and applying a formula derived from Ohm's law. Other non-invasive measurement methods involve hall effect sensors for DC and AC and inductive coils (current transformer) for AC.\\
+Current sensors determine the power consumption and detect whether the device is turned on or shorted.\\
+Sample current sensor modules are present in figures {{ref>sensor_current1}} and {{ref>sensor_current2}}, and schematic connection to the Arduino Uno in figure {{ref>sensor_current3}}
+<figure sensor_current1>
+{{ :en:iot-open:hardware2:20230925_114306_copy.jpg?300 | Current transformer module for AC}}
+<caption>Current transformer module for AC</caption>
+</figure>
+<figure sensor_current2>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:current_sen_c.jpg?200 | Analogue current meter module 0–50 A}}
+<caption>Analogue current meter module 0–50 A</caption>
+</figure>
+<figure sensor_current3>
+{{ :en:iot-open:getting_familiar_with_your_hardware_rtu_itmo_sut:arduino_and_arduino_101_intel_curie:sch_apz_shemas_current.png?350 | Arduino and current sensor module schematics}}
+<caption>Arduino and current sensor module schematics</caption>
+</figure>
+The example code:
+<code c>
+//Define an analogue A0 pin for current sensor
+const int currentPin = A0;
+//Scale factor of the sensor use 100 for 20 A Module and 66 for 30 A Module
+int mVperAmp = 185;
+int currentReading;
+int ACSoffset = 2500;
+double voltage;
+double current;
+void setup(){
+ Serial.begin(9600);
+}
+void loop(){
+ currentReading = analogRead(currentPin);
+ Voltage = (currentReading / 1024.0) * 5000; //Gets you mV
+ Current = ((Voltage - ACSoffset) / mVperAmp); //Calculating current value
+ Serial.print("Raw Value = " ); //Shows pre-scaled value
+ Serial.print(currentReading);
+ Serial.print("\t Current = "); //Shows the voltage measured
+ //The '3' after current allows to display 3 digits after the decimal point
+ Serial.println(Current,3);
+ delay(1000); //Short delay
+</code>