Touch switch using two NPN transistors and Darlington scheme

General Discussion
1

Hello!
I tried to build the circuit from class eight:How to use NPN transistors to create touch switch (in attached file), it doesn’t work. Is there any mistake in the circuit?

circuit
circuit998×886 101 KB

2

Is this an example of our product suite? If it is made by ourselves, do we need to run the code? Can you have the code available to us?
We will do the test according to your situation.

3

Hello! This circuit doesn’t work because of wrong transistors location.
When i change the it, then the circuit worked.

20230628_154117
20230628_1541171920×1440 312 KB

int ledPin = 13;                // choose the pin for the LED
int touchPin = 0;               // choose the input pin
int touchVal = 0;               // variable for reading the pin

void setup() {
  pinMode(ledPin, OUTPUT);      // declare LED as output
  pinMode(touchPin, INPUT);
  Serial.begin(9600);
}

void loop(){
  touchVal = analogRead(touchPin);
  Serial.println(touchVal);
  delay(1000);
 
  if(touchVal < 5)
  {
    digitalWrite(ledPin, HIGH);
  }
  else
  {
    digitalWrite(ledPin, LOW);
  }
}
4

Very happy for you that you overcame the difficulties and made the work go smoothly.
Please contact us if you have any questions about the product afterward.
Have a great life!