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An open-source infrared induction light control night light

March 05, 2021 by Alan Hathaway

In the schematic design, each feet use a method of resistance partial pressure to change the pin voltage, and the contro


1 LDO (HT7333)


This project is based on AM612 smart infrared sensor design night light


With a 3.3-5V power supply, the LDO (HT7333) is used to voltage to 3.3V.

Onboard 6 patch LEDs, power is 0.5W

Infrared sensitivity is adjusted by variable resistor R4

Opening light delay time by variable resistor R6

Equipped with a Micro USB charging port, charge a power supply lithium battery

Spend a nightlight switch, work when switching opens

Photoactic resistor selection: 0.5m ohm, 5-10K ohm during the day, enabling the voltage dividing resistance of 100K, the OEN-terminal voltage is 0.1VDD during the day, Oen enables it, not working. Night Oen end voltage is 5/6 VDD, Oen enables effective, and the small lamp works.

Circuit Schematic


PCB diagram


Simulation 3D PCB Figure

Simulation 3D PCB Figure

AM612 Working Principle Introduction

Am612 has a total of 6 feet, except for VDD and VSS (GND), REL, OEN, SENSE, ONTIME

Rel: Output pin, after receiving the threshold induction in the infrared PIR, REL will output a high level of a period of time, and the duration is controlled by the ONTIME foot voltage.

OEN: Enable feet, the foot voltage is greater than 0.4VDD, which is enabled when it is less than 0.2VDD. This design is invalid. This design uses the light-sensitive division voltage VDD to control the enable effect of Oen, and it does not light the day. The effect of bright sparkles at night.

SENSE: Sensitive Sensitive Adjustment Feet, according to the potential size on Sense, change the sensitivity of the infrared sensing, the smaller the voltage, the higher the sensitivity, the farther the induction range (requires less than 0.5VDD)

OnTime: Delayed time adjustment pin, change the power of the REL output on the power of the REL output, the larger the voltage, the longer the delay, the delay is (2.3S-4796S), this design The night light delay time can be adjusted around 2.3S-40S.


Alan Hathaway

Alan Hathaway an editor at Utmel.

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