TYPE-C infinite dimming night light V1.0

Infinitely dimmable night light with lithium battery (without MCU)

It's a small thing with no technical content. The circuit design used has been verified many times in other projects before, so you can use it with confidence.

The resistors and capacitors are mainly packaged in 0805, and the type-c is 6p, which is convenient for hand soldering (a few are still 0603 and have been forgotten to change...)

2022-7-15 Update

The top acrylic board is added to protect the filament. After exporting the second pcb file with only the border layer to dxf format, it can be used to cut the acrylic board.

V1.1 appearance improved version: TYPE-C infinitely dimmable night light V1.1 appearance improvement - Jialichuang EDA open source hardware platform (oshwhub.com) 

Although it just changed the appearance, I personally think this version is better

1.Circuit scheme

• Charging and power management: MCP73831T-2ATI/OT
• Switching between external power supply and lithium battery power supply: See the schematic diagram, which is mainly composed of AO3401 and two Schottky diodes. You can probably understand the principle after studying the model of electricity.
• 3V voltage: SGM2036-3.0YN5G/TR
• Lighting: The popular 26MM LED filament, warm white light
• Stepless dimming: SGL8022W (This part refers to this person’s design: touch stepless dimming snowflake lamp (ceramic filament) (novices can also do it!) - Jialichuang EDA open source hardware platform (oshwhub.com) , this chip It’s not that hard to buy, just search it on Taobao and you can use it)

2.Description

• The filament is powered by 3V, and a 100Ω resistor is connected in series to limit the current. The measured voltage at both ends is about 2.56V when working at full brightness under dimming, and it hardly generates heat when working for a long time. This maximum brightness is more suitable for a night light. To increase the brightness, it can be used as a night light. Lighting needs to increase the voltage at both ends or reduce the value of the current-limiting resistor (currently tested, the 3V current-limiting resistor can be selected from 18Ω-100Ω, and it will be a bit hot if no current-limiting resistor is added at all).
• You can also use 3.3v for the lithium battery step-down LDO. The load of this circuit is not too large and you only need a low-voltage drop LDO (rt9013, xc6206, lp5907, etc.). If you use 3.3v, adjust the current limiting circuit according to the desired maximum brightness. value (you can still use 100Ω, this filament is much more durable than expected, just plug it into 5V directly, but the brightness is too high and the heat will affect the lifespan).
• You can wrap scattering paper around the lamp tube (I don't know what to call this thing, it's the kind of frosted texture that diffuses the light source), and the light will be softer and more uniform.
• For assembly, just use m2.5 copper pillars to connect the boards, and the battery is sandwiched in the middle.
• This version of this project is basically a solution verification and entertainment product, but the response has been pretty good when used as a night light for family members. In the future, we plan to add a light control part based on a voltage comparator and a photoresistor (light control is mainly about trying to achieve the effect. Parameters but I don’t have a breadboard or plug-in resistance test).

3. Physical picture