# ESP32 Relay Controller ## Description 12V-powered ESP32 relay dry-contact controller with USB-C data-only programming/debug and an onboard 3.3V rail for the ESP32. ## Project Details - **Owner:** benboy - **Created:** 5/28/2026 - **Last Updated:** 5/28/2026 - **Visibility:** Public - **Domain:** ESP32 relay controller - **Power Requirements:** External 12V input powers relay and 3.3V regulator; USB-C is data-only, not board power. - **Connectivity:** USB-C data-only to ESP32 native USB; WiFi/BLE available from ESP32 module. - **Implementation Details:** Single relay switches an isolated dry-contact output; relay coil driven from 12V by a transistor/MOSFET with flyback protection. - **Operating Voltage:** 12V input, 3.3V ESP32 rail ## Key Components ### BOOT_SW — [6x6mm micro tactile switch](https://www.flux.ai/jecstronic/6x6mm-micro-tactile-switch~igw.md) - Role: Switching - Part Type: Switch - Purchase Url: https://shopee.ph/20Pcs-Micro-Tactile-Switch-Momentary-Tact-DIP-Switch-2Pin-6-X-6mm-Micro-Touch-Push-Button-Switch-High-5mm-6mm-7mm-8mm-9mm-i.1018846655.22773354064?sp_atk=2b55ff5c-bbfc-4967-b7e3-adb8c93c34e2&xptdk=2b55ff5c-bbfc-4967-b7e3-adb8c93c34e2&is_from_login=true - Manufacturer Part Number: PTS645SK43SMTR92 LFS - Role Details: Momentary user button for ESP32 reset/boot control - Manufacturer Name: C&K **Pins:** - P1 [pin 1] - P2 [pin 2] ### D1 — [USBLC6-2SC6](https://www.flux.ai/lcsc/usblc6-2sc6~2e9x.md) - Maximum Clamping Voltage: 17V - Package or Case Code: SOT-23-6_L2.9-W1.6-P0.95-LS2.8-BL - Operating Temperature: -55°C ~ 125°C (TJ) - Breakdown Voltage: 6V - Manufacturer Part Number: USBLC6-2SC6 - Symbol Style: parametric-v1 - LCSC Part Number: C2687116 - Manufacturer Name: UMW(友台半导体) - Role Details: USB 2.0 D+/D- ESD clamp near USB-C connector - Datasheet URL: https://www.lcsc.com/datasheet/C2687116.pdf?spm=wm.sxq.inf.ggs&lcsc_vid=FlkNBAIDRQULVABfFAVZBgZVFVZYBgZSQ1NeBVIFQlExVlNRTlhdUVdURFlXXzsOAxUeFF5JWBYZEEoKFBINSQcJGk4dAgUUFAk%3D - Part Type: ESD Protection Devices - JLCPCB Part Class: Extended Part - Power: 150W - Role: ESD Protection - Peak Pulse Current: 5A **Pins:** - GND [pin 2] - I/O1 [pin 1] - I/O1 [pin 6] - I/O2 [pin 3] - I/O2 [pin 4] - VBUS [pin 5] ### D2 — [SS12](https://www.flux.ai/adrian95/ss12~i7b.md) - Part Type: Diode - Datasheet URL: https://www.onsemi.com/pdf/datasheet/ss19-d.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: SS12 - Manufacturer Name: onsemi - Role: Flyback / Freewheeling - Role Details: Flyback diode across 12V relay coil; cathode to +12V, anode to MOSFET drain/coil low side **Pins:** - A [pin 2] - K [pin 1] ### J1 — [USB-C 2.0 Receptacle](https://www.flux.ai/vasy_skral/usb-c-2p0-receptacle~1xw.md) - Datasheet URL: https://gct.co/files/drawings/usb4105.pdf - Symbol Style: parametric-v1 - Role: USB Connector - Manufacturer Name: GTC - Purchase Url: https://www.digikey.com/en/products/detail/gct/USB4105-GF-A/11198441 - Manufacturer Part Number: USB4105-GF-A - Role Details: USB-C connector for data only; D+/D- routed to ESP32 native USB, CC pins configured as UFP/sink - Part Type: USB C **Pins:** - CC1 [pin 6] - CC2 [pin 12] - D- [pin 7] - D- [pin 9] - D+ [pin 10] - D+ [pin 8] - GND [pin 1] - GND [pin 16] - GND [pin 15] - GND [pin 2] - SBU1 [pin 11] - SBU2 [pin 5] - VBUS [pin 3] - VBUS [pin 14] - VBUS [pin 4] - VBUS [pin 13] ### J2 — [KF128-5.08-2P-AA](https://www.flux.ai/lcsc/kf128-5p08-2p-aa~0pbi.md) - Operating Temperature: -40℃~+105℃ - Connector Gender: Female - Connector Type: Screw terminal - Package or Case Code: CONN-TH_P5.08_KF128-5.08-2P - Manufacturer Name: KEFA(科发) - Connector Rows: 1 - Role: Power Input - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/2408211511_Cixi-Kefa-Elec-KF128-5-08-2P-AA_C474952.pdf - LCSC Part Number: C474952 - Connector Positions: 2 - Current Rating: 24A - Manufacturer Part Number: KF128-5.08-2P-AA - JLCPCB Part Class: Extended Part - Part Type: Screw terminal - Connector Pitch: 5.08mm - Product Info Url: https://lcsc.com/product-detail/New-Quadratic-Unclassified-Data_Cixi-Kefa-Elec-KF128-5-08-2P_C474952.html - Role Details: 2-pin 5.08mm terminal for external 12V input supply **Pins:** - 1 [pin 1] - 2 [pin 2] ### J3 — [282837-3](https://www.flux.ai/adrian95/282837-3~5mc.md) - Part Type: Connector - Role Details: 3-pin 5.08mm terminal exposes relay COM, NO, and NC dry contacts - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.te.com/usa-en/product-282837-3.datasheet.pdf - Role: Dry Contact Output - Manufacturer Name: TE Connectivity AMP Connectors - Manufacturer Part Number: 282837-3 **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] ### K1 — [ACNM1112](https://www.flux.ai/jecstronic/acnm1112~g7y.md) - Manufacturer Part Number: ACNM1112 - Datasheet URL: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/819/CN-M_Relays_DS.pdf - Part Type: Relay - Role: Relay - Manufacturer Name: Panasonic Electric Works - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: 12V coil relay, ESP32-controlled via low-side MOSFET; COM/NO/NC routed to dry-contact terminal **Pins:** - COIL_1 [pin 2] - COIL_2 [pin 5] - COM_1 [pin 1] - COM_2 [pin 6] - N.C. [pin 3] - N.O. [pin 4] ### Q1 — [FS8205A](https://www.flux.ai/lcsc/fs8205a~r2vk.md) - Role Details: Logic-level N-channel MOSFET driven by ESP32 GPIO to switch 12V relay coil - Manufacturer Part Number: FS8205A - JLCPCB Part Class: Extended Part - Manufacturer Name: TECH PUBLIC(台舟) - Role: Relay Driver - Part Type: MOSFETs - LCSC Part Number: C2830320 - Datasheet URL: https://mm.digikey.com/Volume0/opasdata/d220001/medias/docus/7158/5272_FS8205A.pdf - Package or Case Code: SOT-23-6_L2.9-W1.6-P0.95-LS2.8-BR **Pins:** - D1/D2 [pin 5] - D1/D2 [pin 2] - G1 [pin 6] - G2 [pin 4] - S1 [pin 1] - S2 [pin 3] ### RST_SW — [6x6mm micro tactile switch](https://www.flux.ai/jecstronic/6x6mm-micro-tactile-switch~igw.md) - Role: Switching - Manufacturer Name: C&K - Manufacturer Part Number: PTS645SK43SMTR92 LFS - Purchase Url: https://shopee.ph/20Pcs-Micro-Tactile-Switch-Momentary-Tact-DIP-Switch-2Pin-6-X-6mm-Micro-Touch-Push-Button-Switch-High-5mm-6mm-7mm-8mm-9mm-i.1018846655.22773354064?sp_atk=2b55ff5c-bbfc-4967-b7e3-adb8c93c34e2&xptdk=2b55ff5c-bbfc-4967-b7e3-adb8c93c34e2&is_from_login=true - Role Details: Momentary user button for ESP32 reset/boot control - Part Type: Switch **Pins:** - P1 [pin 1] - P2 [pin 2] ### U1 — [ESP32-S3-WROOM-1-N16R8](https://www.flux.ai/adrian95/esp32-s3-wroom-1-n16r8~fs1.md) - Datasheet URL: https://www.mouser.com/datasheet/2/891/esp32_s3_wroom_1_wroom_1u_datasheet_en-2930317.pdf - Role Details: ESP32-S3 module controls relay and connects to USB-C D+/D- for data-only programming/debug - Role: Microcontroller - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: Espressif Systems - Manufacturer Part Number: ESP32-S3-WROOM-1-N16R8 - Part Type: Module - Symbol Style: parametric-v1 **Pins:** - 3V3 [pin 2] - EN [pin 3] - GND_1 [pin 1] - GND_10 [pin 48] - GND_11 [pin 49] - GND_2 [pin 40] - GND_3 [pin 41] - GND_4 [pin 42] - GND_5 [pin 43] - GND_6 [pin 44] - GND_7 [pin 45] - GND_8 [pin 46] - GND_9 [pin 47] - IO0 [pin 27] - IO1 [pin 39] - IO10 [pin 18] - IO11 [pin 19] - IO12 [pin 20] - IO13 [pin 21] - IO14 [pin 22] - IO15 [pin 8] - IO16 [pin 9] - IO17 [pin 10] - IO18 [pin 11] - IO19 [pin 13] - IO2 [pin 38] - IO20 [pin 14] - IO21 [pin 23] - IO3 [pin 15] - IO35 [pin 28] - IO36 [pin 29] - IO37 [pin 30] - IO38 [pin 31] - IO39 [pin 32] - IO4 [pin 4] - IO40 [pin 33] - IO41 [pin 34] - IO42 [pin 35] - IO45 [pin 26] - IO46 [pin 16] - IO47 [pin 24] - IO48 [pin 25] - IO5 [pin 5] - IO6 [pin 6] - IO7 [pin 7] - IO8 [pin 12] - IO9 [pin 17] - RXD0 [pin 36] - TXD0 [pin 37] ### U2 — [AP63203WU-7](https://www.flux.ai/lcsc/ap63203wu-7~j9cl.md) - Operating Temperature: -40 ~ +85℃ - Part Type: AC-DC Controllers & Regulators - LCSC Part Number: C780769 - IC Type: Synchronous Buck Converter - Output Current: 2A - Symbol Style: parametric-v1 - Manufacturer Name: DIODES(美台) - Max Input Voltage: 3.8~32V - Operating Voltage: 4.5V to 60V - Max Output Voltage: 3.3V - Frequency: 1100kHz - Manufacturer Part Number: AP63203WU-7 - JLCPCB Part Class: Extended Part - Role Details: 3.3V fixed buck regulator sized for ESP32 WiFi current peaks from 12V input - Role: Regulator - Datasheet URL: https://www.diodes.com/assets/Datasheets/AP63200-AP63201-AP63203-AP63205.pdf - Package or Case Code: TSOT-26_L2.9-W1.6-P0.95-LS2.8-BL **Pins:** - BST [pin 6] - EN [pin 2] - FB [pin 1] - GND [pin 4] - SW [pin 5] - VIN [pin 3] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/benboy/esp32-relay-controller~yl](https://www.flux.ai/benboy/esp32-relay-controller~yl).* --- *Generated from [https://www.flux.ai/benboy/esp32-relay-controller~yl](https://www.flux.ai/benboy/esp32-relay-controller~yl)*