AVT5789 LED dimming controller with proximity sensor
The driver is recommended for LED strips and some 12V DC LED lamps without current and voltage regulation, as well as traditional 12V DC halogen and incandescent lamps. Bringing your hand close to the sensor activates the system, gently illuminating a light source attached to the system outlet. After the approach of the hands, it will be smooth, slowly fading.
The module responds to a close-up from a distance of 1,5...2 cm. The duration of the lightening and darkening function is about 5 seconds. The entire clarification process is signaled by the flashing of LED 1, and after it is completed, the LED will be permanently lit. After the end of the extinguishing, the LED will turn off.
Construction and operation
The circuit diagram of the controller is shown in Figure 1. It is connected between the power supply and the receiver. It must be powered by constant voltage, it can be a battery or any power source with a current load corresponding to the connected load. Diode D1 protects against the connection of voltage with the wrong polarity. The input voltage is supplied to the stabilizer IC1 78L05, capacitors C1 ... C8 provide the correct filtering of this voltage.
Figure 1. Controller Wiring Diagram
The system is controlled by IC2 ATTINY25 microcontroller. The actuating element is a transistor T1 type STP55NF06. A specialized AT42QT1011 chip from Atmel, designated as IC3, was used as a proximity detector. It is equipped with one proximity field and a digital output that indicates a high level when the hand approaches the sensor. The detection range is regulated by the capacitance of the capacitor C5 - it should be within 2 ... 50 nF.
In the model system, the power is selected so that the module responds to a close-up from a distance of 1,5–2 cm.
Installation and adjustment
The module must be assembled on a printed circuit board, the assembly diagram of which is shown in Figure 2. The assembly of the system is typical and should not cause problems, and the module is immediately ready for operation after assembly. On fig. 3 shows the connection method.
Rice. 2. PCB layout with elements arrangement
The proximity sensor input marked with the letter S is used to connect the proximity field. This must be a surface of conductive material, but it can be covered with an insulating layer. The cell must be connected to the system with the shortest possible cable. There should be no other conductive wires or surfaces nearby. The non-contact field can be a handle, a metal cabinet handle or an aluminum profile for LED strips. Turn the system power off and on again every time you replace the touch field element. This necessity is dictated by the fact that only immediately after the power is turned on does a short-term check and calibration of the sensor and the proximity field take place.
Figure 3. Controller connection diagram
All necessary parts for this project are included in the AVT5789 B kit for PLN 38, available at:
