Cabinet door sensor light

Bilibili video link: Click to play:
Finished product image of cabinet door sensor light:
Function introduction:
1. Automatic light turns on when the door is opened, no additional operation required;
2. Comprehensive battery protection system, with protection circuits for both charging and discharging;
3. Equipped with a charging indicator light, automatically stops charging and turns on when fully charged;
4. Standby power consumption as low as 15 microamps, consuming only 1000 mAh of power over 7 years of standby;
5. Versatile installation method, can be removed at any time and used as a small flashlight;
6. Equipped with a high-brightness button, pressing it will activate the LED at full load, which can be used in conjunction with flashlight mode;
7. Type-C charging interface with CC resistor, supports C to C cable.
Working principle:
The LED driving part of this product uses analog circuits, only the charging and discharging protection uses a ready-made protection chip.
1. Chip Section:
1-1. The charging protection chip is model TP4059, with a maximum programmable charging current of 600mA. R4 is the current programming resistor. The current relationship table is as follows:
1-2. The discharging protection chip is model DW02A. This chip also includes charging protection. Combined with the battery's built-in protection board, it provides triple charging protection and double discharging protection, ensuring your safety.
2. Analog Circuit Section:
2-1. The main LED bead driving section uses only one N-channel MOSFET. The principle is based on voltage division through the gate resistor. When the reed switch is closed due to the door being closed, the gate is pulled low through R11, the MOSFET is cut off, and the LED is off. When the door is opened, the reed switch is open, the gate is pulled high by R12, R13, and R14, the MOSFET conducts, and the LED lights up. R14 connects to Q1B, which is the middle pin of the switch. The switch controls whether Q1B is high or low. If Q1B is low, whether the door is open or not will not affect the LED bead's off state.
2-2. The working principle of the high-brightness button is to use a very small current-limiting resistor R18, connected in parallel with three larger fixed current-limiting resistors R15-1, R15-2, and R15-3, to make the LED work at full load.
2-3. When the door is closed, the reed switch closes. At this time, R11, R12, R13, and R14 are directly connected in series across the power supply. This is why R12, R13, and R14 have such large values. The current at this time is
3.7 ÷ (100000 + 100000 + 100000 + 1000) = 0.0000122 amps, which is equivalent to 12 microamps. Adding the standby power consumption of the two chips, the actual measured standby current of the entire device is only 15 microamps, which is extremely low power consumption. It only consumes 1000 mAh of power in 7 years of standby.
Minor details & precautions for replication:
1. This open-source project contains two versions; please replicate V2.0. V1.0 was a design failure, but because of the effort I put into it, I couldn't bear to delete it, so I'm keeping it here as a memento.
2. Version V2.0 is compatible with battery model 803040, using PH2.0 terminals for connection. It also has lead-out pads for wire connection.
3. Regarding the backplate, this open-source project offers two material options: PCB and acrylic. Acrylic is recommended as it's lighter, more dimensionally accurate, and has a more perfect appearance.
4. The open-source panel design includes the LED diffuser plate (the small, semi-transparent cube), which is not recommended. While it softens the light, it also reduces the illumination angle, creating noticeable dark corners when placed in cabinets.
5. Installation methods include hanging, magnetic attachment, adhesive, and various other methods I haven't considered. In short, it's highly versatile. Feel free to use your imagination and discuss in the comments section.
Thank you for watching, and have a wonderful day!