ESP32-S3 door access controller with USB-C Li-ion charging, VBAT and 12V lock power, dual 3.3V rails, I2C sensor headers, reed/PIR inputs, LED indicators, buzzer, and MOSFET plus relay lock outputs. External modules and field devices remain represented by connector placeholders with documented pinouts for later PCB and validation work.

4-layer marine GPS timing and communication device using nRF52840, u-blox ZED-F9P GNSS with external active antenna via u.FL, 915 MHz LoRa radio, Li-ion battery with USB-C charging, separate clean GNSS LDO and digital 3.3V rail, SPI memory LCD, RGB LEDs, buzzer, and 6-axis IMU. PCB target is a 70 mm circular layout with strict RF zoning, dedicated ground plane, 50 ohm RF traces, physical separation between GNSS and LoRa, and low-noise placement suitable for harsh marine environments.

Battery-powered ESP32-WROOM-32 design with MAX30102 PPG sensor, MCP73871 single-cell Li-ion charging and power-path management, 3.3V regulation, and two low-current output terminals.

Passive BLE tracker locator with ESP32-S3, 2.4-inch TFT UI, USB-C charging, LiPo battery power, GNSS logging, 2.4 GHz BLE/Wi-Fi energy detection, passive BLE advertisement identification in firmware, and optional ADL5904 cellular-band sensing.

Compact kayak and canoe impact sensor PCB with USB-C Li-ion charging, ATmega328P-AU control, ADXL345 breakout sensing, 3.3V regulated power, OLED and ISP headers, and corner mounting holes.

Compact kayak and canoe impact sensor PCB with USB-C Li-ion charging, ATmega328P-AU control, ADXL345 breakout sensing, 3.3V regulated power, OLED and ISP headers, and corner mounting holes.

BLE wearable flex PCB with LiPo charging, PPG plus skin temperature, 3-channel EMG, IMU, and piezo impact sensing for a smart compression sleeve

Portable Raspberry Pi Pico and NEO-6M GPS tracker powered by a single-cell Li-ion battery, with USB-C charging input, CC resistors, and USB-line ESD protection. Designed to support about 65 mA active current and roughly 30 hours from a 2000 mAh cell, following the performance targets from the evaluation paper.

Bilateral smart running insole data logger using two nearly identical ESP32-S3 pressure-sensing PCBs. Left variant is an ESP-NOW slave without microSD; right variant is the master with microSD logging. Both preserve the 16-zone FSR mux front end, LiPo charging, AP2112K regulation, USB-C charging input, JST battery connector, and the 280mm x 90mm 2-layer low-profile insole form factor.

Compact 2S Li-ion charger for Sony NP-FZ100 battery using DC input, 8.4 V CC/CV charging, automatic termination, reverse polarity, overvoltage, overcurrent, and thermal protection, with defined B+ and B- battery outputs and PCB-buildable component choices.

Cow health-monitoring wearable PCB for a cow-mounted device. Rear strap electronics target 20-25 g and front sensing assembly target about 15 g. Uses an ESP32-based sensor controller, 200 mAh LiPo battery, battery charging circuitry, and interfaces for ammonia, methane, IR temperature, and saliva sensing. Design must tolerate moisture, mucus, debris, vibration, fur contact, and tongue/lick exposure while remaining compact and lightweight for wearable use.

FlowState Headband EVT1 — 4-Channel EEG Calibration Device Closed-loop EEG neurofeedback headband for theta/beta baseline calibration. 4-layer mixed-signal PCB, 40x30mm. Core ICs: - ADS1299-4PAG (TI) — 4-channel 24-bit EEG analog front end, SPI interface, 250 SPS - nRF5340 (Nordic) — Dual-core BLE 5.3 SoC, 128 MHz app core + 64 MHz network core Key requirements: - Separate analog and digital power domains (dual LDO: LP5907 for AVDD, AP2112 for DVDD) - Split analog/digital ground planes with single-point connection - 6 electrode inputs (4 active + 1 reference + 1 DRL) with individual TVS ESD protection on each - LIS2DH12 accelerometer (I2C) for motion artifact detection - MCP73831 USB-C battery charging (300-500 mAh LiPo) - 2.4 GHz chip antenna or PCB trace antenna at board edge with 10mm keepout - Conformal coating for sweat/moisture protection Reference designs: - Analog front-end: TI ADS1299 EVM (SBAS499) - Digital/BLE: Nordic nRF5340 DK reference schematic Critical constraint: Microvolt-level EEG signals — analog input routing and power supply filtering are the highest-priority layout concerns.

Wearable closed-loop ultrasonic monitoring and transcutaneous neuromodulation system based on ESP32-C3, powered from a 7.4 V 1000 mAh LiPo battery with TP4056 charging, MT3608 boost conversion, AMS1117-3.3 regulation, JSN-SR04T ultrasonic sensing, LED and buzzer alerts through a BC547 driver, and a reserved neuromodulation interface for future integration.

Compact wearable smart cat collar PCB focused on ultra-low power, miniaturized size, curved-edge waterproof-friendly mechanical fit, GNSS tracking, motion sensing, RFID compatibility, Li-ion charging, and robust mass-production readiness.

Wearable health device prototype schematic with ECG sensing via AD8232, motion sensing via BNO085 or BMI270 IMU breakout, on-board processing using TI TM4C123G LaunchPad or MSPM0G3507 LaunchPad, optional ESP8266 Wi-Fi, LiPo battery charging with MCP73831, regulated 3.3 V power from TPS63031 buck-boost or AP2112 LDO prototype option, and user interfaces including electrode connector, JST battery connector, programming header, and optional on/off switch.

Production-defensible Rev B ear tag tracker using nRF9151 with separate LTE and GNSS antennas, solar-assisted LiPo charging, battery protection, SPI NOR flash, NFC, eSIM, I2C sensors, Tag-Connect SWD, grouped EVT test points, and RF/power zoning on a 40 mm x 24 mm 4-layer PCB.

Misty Pink Replicator schematic finalized for layout handoff with ESP32-S3, USB-C battery charging, T5838 always-on wake microphone, CI1302 backup ASR analog microphone front end, HTEW0154T8 SPI e-ink display, standardized power/test nets, and final ERC-clean baseline.

Exposed bare PCB smartwatch with ESP32-C3, MAX30102, IP5306 charging, microSD, haptic motor, USB-C, and 40 mm round 2-layer layout for JLCPCB BASIC assembly.

Ultra-compact nRF52 (WLCSP) + accelerometer + optical AFE with USB-C charging

The "Green Dot 2040E5" Board is a Node that interfaces RS485 Sensor probes and can log information to the cloud using LoRa Connectivity. It uses the XIAO RP2040 and the LoRa-E5 (STM32WLE5JC) modules from Seeed Studio to do its magic. It also has amazing power management capabilities (Solar charging, Battery protection, etc) that make it very useful for IoT applications #internetOfThings #smartHomeDevices #SeeedStudio #XIAO #LoRa #RP2040 #IoT

Smart 12V Power / Charging / Protection Controller (Ideal Diode + PV MPPT + EXT CC/CV + OV/UV + Arduino)

Architectural Lavender Translation Collar – ESP32‑S3 Wi‑Fi + LoRa, USB‑C, Li‑ion, low‑power design Overview Experience a cutting-edge IoT solution with this low‑power board built around the ESP32‑S3‑MINI‑1‑N8. Designed for seamless Wi‑Fi (2.4 GHz), BLE, and LoRa (868 MHz) connectivity, this board integrates ENS161 and ENS210 sensors over I2C alongside an RFM95W‑868 LoRa radio on SPI. It is powered via a 3.7 V Li‑ion cell with USB‑C charging up to 500 mA, complete with full battery protection, a robust 3.3 V rail tailored for Wi‑Fi burst currents, and per‑peripheral power gating to enhance energy efficiency. Core Features • MCU: ESP32‑S3‑MINI‑1‑N8 equipped with an onboard PCB antenna for 2.4 GHz Wi‑Fi/BLE, ensuring optimal wireless performance. • Sensors: Integrated ENS161 and ENS210 sensors utilize a shared I2C bus with controllable 4.7 kΩ pull‑ups for streamlined communication. • LoRa Radio: The RFM95W‑868 module, connected via SPI, enables long‑range communication at 868 MHz. Power & USB‑C Connectivity • Battery: A reliable 3.7 V 1200 mAh Li‑ion battery connected via a right‑angle JST‑PH 2‑pin connector features built‑in battery protection. • Charging: The USB‑C receptacle, with CC resistors and TVS protection on D+/D− along with series resistors, supports fast, safe charging with a current limit of 500 mA. • Regulation: A dedicated 3.3 V regulator capable of handling Wi‑Fi burst currents coupled with bulk and high‑frequency decoupling ensures stable operation, supported by status LEDs indicating power and charge states. Low‑Power Control • Peripheral Management: Load switches allow selective power‑gating of the ENS161, ENS210, and RFM95W modules, controlled directly by ESP32‑S3 GPIOs. • Energy Efficiency: Controllable I2C pull‑ups minimize idle current, vital for prolonged battery life in IoT applications. RF and Antenna Integration • 2.4 GHz: Utilizes the integrated PCB antenna on the ESP32‑S3 with proper ground/metal keep‑out zones for optimal signal integrity. • 868 MHz: Features a controlled‑impedance feed from the RFM95W to a PI matching network (C‑L‑C pads) with flexible antenna options—selectable via SMA connector, chip antenna, or PCB trace—and includes RF ESD protection. Connectivity & Debug Features • USB‑C Interface: Provides secure data connectivity with integrated safeguards and proper terminations. • Debugging: A comprehensive programming/debug header exposes EN, BOOT, and UART lines, with test points on key rails and buses (3V3, VBAT, SCK, MOSI, MISO, SDA, SCL, RESET/EN, GND) to simplify development and troubleshooting. Design Verification • Rigorous ERC/DRC and decoupling checks ensure adherence to component ratings and optimal signal routing. • Maintain RF keep‑outs and impedance‑controlled traces for both 2.4 GHz and 868 MHz paths, securing reliable performance even during high‑intensity operations. #IoT #ESP32S3 #LoRa #LowPowerDesign #USB-C #WirelessConnectivity #BatteryPowered #RFDesign

Rechargeable Non-Lethal Bee Venom Stimulator with TP4056 Charging, MT3608 Boost to 9–12 V, NE556 Dual-Timer Pulse Control, and NPN Output Drivers on Single-Layer Through-Hole PCB #LiIon #USBCharge #Boost #NE556 #NPNDrivers #ThroughHolePCB

Battery-Powered Audio/Bluetooth System with External TP4056 Charging, Dual MT3608 Boost Rails, and Star-Grounded Power Domains

4×4 cm USB-C PD & Qi Wireless Power Bank with Li-Po Charging, Power-Path Management, 3.3 V LDO, Full-Bridge Gate Driver, LED Resistors, and Corrected 5 V Output Feedback (Schematic Cleaned: Redundant Net Portals/Passives Removed, Fuel-Gauge LED Channels Verified, ERC/DRC Issues Resolved)