KY-036 Metal Touch Sensor Module

The KY-036 Module is a metal-touch sensor circuit board that uses a Darlington NPN transistor. It can detect changes in electrical conductivity and works with microcontrollers like Arduino, Raspberry Pi, and ESP32. The module has both digital and analog outputs. The digital output acts like a switch that turns on when touched, while the analog output can measure the intensity of the touch. It has an on-board potentiometer to adjust the touch sensor's sensitivity.

KY-036 Metal Touch Sensor Module Specifications

The quick specifications of this sensor module is given below:

• Module: Metal Touch Sensor
• Type: Analog/Digital
• Main Chips: LM393, KSP13
• Pin Connector to board: 4 Pins
• Operating Voltage: DC +3.3V to +5V
• PCB Color: Red
• Board Dimensions (L x W x H): 43 x 16 x 15 mm
• Weight: 4gm

Pinout of KY-036 Metal Touch Sensor Module

The module has 4 male header pins those are - Pin (A0): Analog Signal Pin (G): Ground Pin (+): DC +3.3V to +5V Pin (D0): Digital Signal

Working Explanation of KY-036 Metal Touch Sensor Module Circuit

Schematic of the KY-036 metal touch sensor module circuit is shown below.

Components are used in the circuit - U₁: IC LM393, Q₁: KSP13 Darlington Transistor, VR₁: 100kΩ Multiturn Potentiometer, R₁ & R₄: 10kΩ, R₂ & R₆: 100kΩ, R₃: 150Ω, R₅: 1kΩ, L₁ & L₂: Red LED, and P₁: 4 pin Male header.

The module integrates both analog and digital circuits, designed to operate within a voltage range of 3.3-5V DC. It has an LED (L1) to indicate the power supply status through blinking.

When the base of the Darlington NPN transistor (Q1) is touched, it becomes activated even by a small touch current. This allows a flow of current through a potentiometer (VR1) and a resistor (R3) to ground. The combination of the potentiometer (VR1) and the resistor (R3) acts as a voltage divider that produces a reference voltage. This reference voltage is then taken as the analog output (A0) of the circuit, and the sensitivity of the touch sensor can be adjusted by the Multiturn potentiometer (VR1).

A LM393 Dual Comparator IC (U1) is used in the circuit for a digital functions, which contains two comparators. The analog output from the voltage divider (VR1 and R3) is fed into the inverting input (pin-2) of the first comparator, while a fixed reference voltage from a second voltage divider (R2 and R6) is connected to the non-inverting input (pin-3) of the same comparator.

When a touch is detected and current flows through the touch sensor (Q1), the reference voltage across the voltage divider (VR1 and R3) decreases. If this voltage drops below the reference voltage of the voltage divider (R2 and R6) at the non-inverting input of the first comparator, the output at pin-1 goes high.

The output from the first comparator is connected to a pull-up resistor (R1), which ensures a defined logic level for the output signal (D0). This high signal from the first comparator is also sent to the non-inverting input (pin-6) of the second comparator, while the reference voltage from the voltage divider (R2 and R6) is connected to the inverting input (pin-7) of the second comparator.

When the first comparator outputs a high signal in response to the touch, the second comparator checks if this high signal exceeds the reference voltage from the divider (R2 and R6). If the signal from the first comparator is greater than the reference, the second comparator outputs a low signal at its output (pin-6). This low signal makes the LED (L2) blink.

KY-036 Arduino Programming Code

This Arduino sketch will read values from the KY-036 metal touch sensor module. When you touch the transistor base, the digital output will send a HIGH signal to the Arduino, and the Arduino's onboard LED will turn ON.

Additionally, the analog output returns a high value when no touch is detected; this value depends on the supplied voltage and the position of the potentiometer's touch sensing threshold. When you touch the transistor base, the output value will decrease. Use Tools > Serial Plotter in the Arduino IDE to visualize the graphical values from the analog output.