Mains-operated Capacitive Sensor
The described circuit functions as a capacitive touch sensor that responds to the proximity of a human body, effectively detecting changes in capacitance when a conductive object, such as a human hand, approaches or touches the sensor. The circuit typically operates at half the mains supply voltage, allowing it to control low-power devices like lamps and buzzers safely.
The core component of the circuit is a capacitive sensing element, which can be made from a conductive plate or a PCB trace. This element is connected to a signal processing unit, often utilizing an operational amplifier or a microcontroller to interpret the changes in capacitance. When a person approaches the sensor, the capacitance increases, triggering the output of the circuit.
To ensure reliable operation, the circuit may include a resistor-capacitor (RC) network that helps filter out noise and stabilize the sensing signal. The output stage can be designed using a relay or a transistor to switch the connected load, such as a lamp or a buzzer, on or off based on the detected proximity.
In practical applications, this circuit can serve as an alternative to traditional door alarms or other capacitive sensor systems. It is particularly useful in environments where touchless operation is preferred, enhancing user convenience and safety. Proper calibration and placement of the sensor are crucial to optimize its sensitivity and ensure effective operation in various settings.This very simple circuit acts as a high sensitivity capacitive sensor. Lamps and/or Buzzers are operated at half the mains supply voltage when a part of the human body comes in contact with the sensor or approaches it at a close distance. The circuit can be used as an alternative to the Door Alarm or Capacitive Sensor circuits, already available on this website.
🔗 External reference
Related Circuits
This circuit features a micro vibration sensor, a trigger delay circuit, and a control circuit, as illustrated in the accompanying figure. The micro vibration sensor comprises a vibration sensing device and a high power amplifier circuit, enabling it to...
A 2002 Blazer was diagnosed with error codes P0155 and P0756, indicating a malfunction in the O2 sensor heater circuit and a performance issue with the shift solenoid B circuit. The vehicle initially has power, but it loses power...
The circuit utilizes a 555 integrated circuit (IC) functioning as an astable multivibrator. When a positive 9 volts is applied to pin 8, the circuit generates sound through a speaker. The connection to pin 8 is routed through a...
An affordable electronic device useful for demonstrating electrostatic phenomena. Ahern's instrument serves as an effective substitute for the tonal electrostatic voltmeter. It provides polarity-dependent information about electric charge motion that conventional instruments do not offer. This apparatus is easy...
The following circuit illustrates the use of the LM324 in a parking sensor circuit diagram. Features: When the obstacle is beyond 25 cm, none of the above LEDs will activate. The LM324 is a quad operational amplifier that is commonly...
The final step involves connecting the IR LEDs, resistors, and IR receivers to the Arduino. Begin by connecting the +5V pins of the IR receivers (the right pin when facing the receiver) with red wires directly to the +5V...