Schematic and PCB design for an ESP32, specifically a Wemos Lolin D2 mini shield to control low power (~200mA) monochromatic fairy lights. These monochromatic fairy lights function as bidirectional LEDs, where alternating the polarity on the two wires changes which half of the LEDs illuminate.
My wife frequently purchases cheap battery/USB monochrome string lights at stores locally or online retailers such as Aliexpress. I wanted to be able to take advantage of these lights to automate them in my home automation system, namely a set we have covering our curtains that I would like to toggle based on sunset. https://www.aliexpress.com/item/1005007634861597.html
I was looking for a device to satisfy the following requirements:
- The device should be able to control at least one set of string lights.
- The device should be able to control the brightness of the lights.
- The device should be able to control them via Home Assistant.
ESPHome configuration: https://github.com/kingmercian/esphome/blob/4c16731de8fa22333e613f6e8b42984a3e44136c/curtain-leds.yaml
| Part | Type | Footprint | Designator | Quantity |
|---|---|---|---|---|
| ESP32 S2 Mini | Microcontroller | N/A | N/A | 1 |
| 1K | Resistor | 0805 | R1, R2, R3, R4 | 4 |
| MMBT2907 | Transistor | SOT-23 | Q1, Q3 | 2 |
| MMBT2222 | Transistor | SOT-23 | Q2, Q4 | 2 |
None for my usage but if I build these in future I would make some changes:
- add a diode between the transistor and LED output
- add terminal blocks to attach LEDs
- add button to toggle through LED patterns (control through software)
- add switch to disable LED output