This project is a WiFi Gesture Light Switch controlled by an ESP32 microcontroller. It leverages APDS-9960 and CH340C ICs for gesture recognition and USB communication respectively. Essential components include diodes for voltage protection, LEDs for status indication, and an AMS1117 voltage regulator to ensure a stable power supply. Connectors like USB Type-C are used for power and data transfers. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #thermostat #referenceDesign #edge-computing #edgeComputing #espressif #template #reference-design

This project is a WiFi Gesture Light Switch controlled by an ESP32 microcontroller. It leverages APDS-9960 and CH340C ICs for gesture recognition and USB communication respectively. Essential components include diodes for voltage protection, LEDs for status indication, and an AMS1117 voltage regulator to ensure a stable power supply. Connectors like USB Type-C are used for power and data transfers. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #thermostat #referenceDesign #edge-computing #edgeComputing #espressif #template #reference-design

This project is a WiFi Gesture Light Switch controlled by an ESP32 microcontroller. It leverages APDS-9960 and CH340C ICs for gesture recognition and USB communication respectively. Essential components include diodes for voltage protection, LEDs for status indication, and an AMS1117 voltage regulator to ensure a stable power supply. Connectors like USB Type-C are used for power and data transfers. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #thermostat #referenceDesign #edge-computing #edgeComputing #espressif #template #reference-design

Digitally controlled 24 V to 0-12 V 1 A buck converter with STM32G4 MCU, CC/CV regulation, SWD debug, SPI expansion connectors, and placeholder power I/O connectors.

This project is a WiFi Gesture Light Switch controlled by an ESP32 microcontroller. It leverages APDS-9960 and CH340C ICs for gesture recognition and USB communication respectively. Essential components include diodes for voltage protection, LEDs for status indication, and an AMS1117 voltage regulator to ensure a stable power supply. Connectors like USB Type-C are used for power and data transfers. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #thermostat #referenceDesign #edge-computing #edgeComputing #espressif #template #reference-design

This project is a WiFi Gesture Light Switch controlled by an ESP32 microcontroller. It leverages APDS-9960 and CH340C ICs for gesture recognition and USB communication respectively. Essential components include diodes for voltage protection, LEDs for status indication, and an AMS1117 voltage regulator to ensure a stable power supply. Connectors like USB Type-C are used for power and data transfers. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #thermostat #referenceDesign #edge-computing #edgeComputing #espressif #template #reference-design

This project is a WiFi Gesture Light Switch controlled by an ESP32 microcontroller. It leverages APDS-9960 and CH340C ICs for gesture recognition and USB communication respectively. Essential components include diodes for voltage protection, LEDs for status indication, and an AMS1117 voltage regulator to ensure a stable power supply. Connectors like USB Type-C are used for power and data transfers. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #thermostat #referenceDesign #edge-computing #edgeComputing #espressif #template #reference-design

ChargeGuard Gateway - PCB layout review status: schematic power tree review is clean; remaining work is PCB-layout-only cleanup. Current DRC inventory: 136 Overlapping Copper, 56 Floating Copper, 88 Airwires, 0 Missing Footprints, 0 Invalid Layer, 0 Important Overrides. Priority 1: protected input and power-path regions around VIN_PROTECTED, VIN_FILTERED, +5V_MAIN, +3V3_MAIN because these can block reliable routing and copper pours. Manual PCB editor tasks: remove/reshape overlapping copper, reconnect broken traces or redraw routes causing airwires, delete stranded copper islands, inspect ambiguous pad-to-trace shorts around power devices and connectors. Agent-preparable tasks: maintain issue inventory, classify nets and priorities, preserve stackup/documentation, define DRC recheck loop, and guide Auto-Layout sequencing after manual copper cleanup. Recheck loop: fix one issue class or one critical region at a time, rerun DRC, confirm counts decrease, then move to next batch until airwires/floating copper/overlaps are zero. Completion checklist: 1) clear power-path overlaps, 2) remove floating copper islands, 3) close all airwires, 4) rerun DRC after each batch, 5) confirm clean layout before manufacturing export.

Introducing our innovative modular, AI-powered DIY laptop carrier board project! This design focuses on a step-by-step approach, starting with a solid architectural scaffold that lays the groundwork for a high-performance system. The project is built around a hierarchical schematic structure including: • A Top Sheet outlining the system overview and power tree • SoM Connectors organized into three 100-pin assemblies (two CM4/5-compatible and one dedicated to high-speed operation) • Dedicated Power/PD management • An M.2 A+E interface for the Coral TPU (PCIe x1 from PORT0) • An M.2 M-key interface for an NVMe SSD (PCIe x2 from PORT1) • Comprehensive USB & Hub configurations • A microSD integration module • Supervisory and Reset controls The design aligns with cost-effective 4-layer board stackup practices (JLCPCB friendly) while following best high-speed design guidelines for USB/PCIe integrity. The integrated silkscreen placeholders feature custom sci-fi fonts for a unique, personal branding touch. Key routing notes include precise PCIe lane mappings based on the Orange Pi CM5 manual, ensuring clean ground return paths, effective decoupling, and proper AC-coupling placement. With paired USB hubs optimized for minimal depth and latency and robust power sequencing strategies, this project is poised to evolve into a high-speed, scalable prototype. #DIYElectronics #ModularDesign #PCBDesign #EmbeddedSystems #PCIe #USBDesign #OrangePiCM5 #TechInnovation #HighSpeedElectronics

System Architecture Overview with PWM Interface, Power Stage, Protections, EMI Filters, Connectors, Hall-Effect Current Monitoring, 4-pin JST-XH Control Header, Isolation & Default-OFF PWM Behavior, Compact Mechanical Layout #hall-sensing #isolated-control #compact-layout

This project is a design for a UV sensor circuit based on the Lite-On LTR-390UV-01. Key components include a voltage regulator (AP2112K-3.3TRG1), level-shifting N-channel MOSFETs (BSS138), resistors, and capacitors. The circuit interface includes I2C communication and power connections, facilitated through JST connectors. #referenceDesign #industrialsensing #liteon #template #reference-design

This project is a design for a UV sensor circuit based on the Lite-On LTR-390UV-01. Key components include a voltage regulator (AP2112K-3.3TRG1), level-shifting N-channel MOSFETs (BSS138), resistors, and capacitors. The circuit interface includes I2C communication and power connections, facilitated through JST connectors. #referenceDesign #industrialsensing #liteon #template #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

This is a climate control system reference design with a STM32WB5 microcontroller, power manager IC, USB Type-C, JST connectors, and an LCD driver. #referenceDesign #edge-computing #edgeComputing #stm #template #iot #control #BLE #reference-design

Universal Serial Bus (USB) is an industry standard that establishes specifications for cables and connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers

A presence sensing device powered by a mean well AC DC converter with a ESP32 C3 for it's brain plus a ld2410 mmwave module. the relay can be used to switch mains power. the ld2410 is connected through the terminal connectors.

Project Title: Plant Monitoring and Irrigation System Overview: This system is based on the ESP32-S3 and is designed to manage irrigation for a multi-floor building. Key Features: Multi-Floor Operation: The system controls three separate floors. Each floor's irrigation can be managed independently. Irrigation and Pump Control: Each floor uses a solenoid valve to regulate water flow. The solenoid valves are operated via MOSFETs. A relay engages an AC water pump when a MOSFET triggers a solenoid valve. Hardware Interconnects: Screw Terminal connectors are added for connecting the solenoid valves and the motor pump. A DC Jack is included to supply power to the system. User Interface & Connectivity: Two JST connectors are provided for integrating an OLED display, a rotary encoder, and a pushbutton. Future enhancements may include the addition of soil moisture sensors. Remote Control: The system is designed for future integration with Blynk IoT. Blynk IoT will offer both manual control and timer-based irrigation modes for each floor.

Programmable USB Type‐C Controller with Power Delivery(PD) support. Include ESD Protection Diodes. With JST connectors and with block terminal connectors for VBUS #project-template #USB #typec #powerdelivery #project

This project is a simple operational amplifier circuit using a UA741CP chip. It provides essential differentiation and integration functions, featuring connections for power, input, and output. Two resistors, one capacitor, and several connectors complete the circuit design. #project

CNC hydraulic press brake controller with STM32H743, ADS1256, 5x DAC8501 ±10V outputs, 3x AD598 LVDT interfaces, isolated 24V digital inputs, 100BASE-TX Ethernet, watchdog, E-stop hardware disable, and 4-layer 220mm x 160mm PCB architecture. Domains: field 24V I/O, precision analog, logic/Ethernet. Safety behavior: E-stop and valve-disable force all analog command outputs to 0V-safe state and disable field enables; watchdog and power-good supervisor reset MCU on comms or rail faults. PCB constraints: L1/L4 signal+components, L2 solid GND, L3 power plane, 1.0mm board inset margin, RJ45 at edge, field connectors on opposite edge, isolation corridor between field wiring and logic/Ethernet, 4x M4 plated mounting holes inset 10mm from corners.

Discover the benefits of the HC32L110 microcontroller with our compact and versatile breakout board, designed to streamline development and testing for various applications. This user-friendly solution offers essential components like decoupling capacitors, a 32MHz crystal oscillator, and accessible power supply connections. The breakout board also features 0.1" pitch connectors, allowing for easy integration of I/O pins into any project. Unlock the full potential of the HC32L110B6YA-CSP16 microcontroller for rapid prototyping and smooth deployment with our ingeniously designed breakout board.

sEMG-DAQ is a wearable 6 channel data acquisition unit for capturing surface electromyographic (sEMG) signals from human arm muscles using SJ2-3593D jack connectors while conditioning, digitizing, processing and transmitting them as sEMG data to an external AI accelerated board through an SM12B-SRSS IDC connector where AI models are run for various applications including robotic control, muscle signals medical assessment and gesture recognition. The board leverages an INA125P instrumentation amplifier together with filter stages utilizing LM324QT op-amps for conditioning and an STM32G4A1VET6 microcontroller for the digitization, processing and data transmission of the signals. Since AI models can only be as good as the data, the design of such a DAQ is necessary to ensure clean, reliable and real-time data for AI applications requiring sEMG data. The board also has USB-FS and JTAG to cater for debugging. The power (5V) is fed through a screw terminal and is regulated by two LDK320AM LDO regulators to offer 5V, 3.3V and 1.8V to meet the requirements of various components on the board.

Haptic Glove Controller Board NUCLEO-F411RE based Fixed Servo Connections to match standard servo wiring Revised footprint of 2n3904s transistors since base and emitter footprint were swapped Larger power traces Swapped SDO and SDI of SPI Lines to the FPC connector so it matches with peripheral.

Haptic Glove Controller Board NUCLEO-F411RE based Fixed Servo Connections to match standard servo wiring Revised footprint of 2n3904s transistors since base and emitter footprint were swapped Larger power traces Swapped SDO and SDI of SPI Lines to the FPC connector so it matches with peripheral.

sEMG-DAQ is a wearable 6 channel data acquisition unit for capturing surface electromyographic (sEMG) signals from human arm muscles using SJ2-3593D jack connectors while conditioning, digitizing, processing and transmitting them as sEMG data to an external AI accelerated board through an SM12B-SRSS IDC connector where AI models are run for various applications including robotic control, muscle signals medical assessment and gesture recognition. The board leverages an INA125P instrumentation amplifier together with filter stages utilizing LM324QT op-amps for conditioning and an STM32G4A1VET6 microcontroller for the digitization, processing and data transmission of the signals. Since AI models can only be as good as the data, the design of such a DAQ is necessary to ensure clean, reliable and real-time data for AI applications requiring sEMG data. The board also has USB-FS and JTAG to cater for debugging. The power (5V) is fed through a screw terminal and is regulated by two LDK320AM LDO regulators to offer 5V, 3.3V and 1.8V to meet the requirements of various components on the board.

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.

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.

SmartDeskPet v1.0 Shield Stage 1 status: - Goal: 5V input -> dual AMS1117-3.3 rails (+3V3_MCU and +3V3_WIFI) with common GND. - Note: Keep power nets explicitly named (avoid unnamed nets) to keep ERC happy. Stage 1 completion checklist: - Mark J1 Pin_1 (+5V) as a Power Output pin to satisfy ERC power-driver checks. - Verify all GND symbols/returns are on the same GND net. - Keep +5V_SERVO isolated from the main +5V net (only share GND). Stage 2 preparation notes (MPN/LCSC + layout constraints): - MPN/LCSC targets to define before Stage 2 exit: - AMS1117-3.3 (SOT-223): set exact MPN and (optionally) LCSC PN for both U1 and U2. - 100nF capacitor (0603): set MPN/LCSC for all 0603 100nF decouplers. - 4.7k resistor (0603): set MPN/LCSC for I2C pull-ups R1 and R2. - 1000uF bulk capacitor (radial): set MPN/LCSC for C7 (CP_Radial_D10.0mm_P5.00mm). - DC005 power jack/regulator input: select exact DC005 footprint + MPN/LCSC (if used). - 2.54mm headers/sockets: set MPN/LCSC for H1, H2, J1, J3, J4, J5, P3, P4, P5, and J2. - ESP-01S antenna keepout: - Reserve a copper keepout under and in front of the ESP-01S onboard antenna. - No copper pours/traces/components in the antenna region (top and bottom) per module guidelines. - H1/H2 header spacing: - Maintain 1000 mil spacing between H1 and H2 header centerlines (shield mechanical requirement). - Silkscreen placeholders: - Add silkscreen labels for: 5V IN, GND, +3V3_MCU, +3V3_WIFI, SERVO1, SERVO2, I2C SDA/SCL, DHT11, ASRPRO UART2, ESP-01S UART3. - Add placeholder text for: MPN, LCSC, board revision, and date code. Stage 3 layout constraints (placement and routing guidance): - Connector placement strategy: - Place H1 and H2 first to lock the shield mechanical interface; enforce 1000 mil spacing. - Place J1 and any DC005 input at the board edge for easy access. - Designated power area planning: - Group U1, U2, and C7 near the 5V entry point; keep high-current 5V and regulator loops short. - Use wide copper for +5V and any servo supply; stitch GND around power section. - Antenna keepout boundaries: - Place J2 (ESP-01S socket) at a board edge with the antenna facing outward. - Enforce a top-and-bottom copper keepout in the antenna region; keep noisy power traces away.

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

TECHNICAL ASSIGNMENT AND DESIGN GUIDE Active Three-Way Crossover on NE5532 Powered by AM4T-4815DZ and Amplifiers TPA3255 (Updated Version) 1. GENERAL PURPOSE OF THE DEVICE The goal of the development is to create an active three-way audio crossover for one channel of a loudspeaker system, working with the following drivers: LF: VISATON W250 MF: VISATON MR130 HF: Morel MDT-12 Each frequency range is amplified by a separate power amplifier: LF: TPA3255 in PBTL mode (mono) MF + HF: second TPA3255 in stereo mode (one channel for MF, the other for HF) The crossover accepts a single linear audio signal (mono) and divides it into three frequency bands: Range Frequency Range LF 0 – 650 Hz MF 650 – 2500 Hz HF 2500 Hz and above Filter type: Linkwitz–Riley 4th order (24 dB/oct) at each crossover point (650 Hz and 2500 Hz). The crossover must provide: minimal self-noise; no audible distortion in the audible range; stable operation with NE5532 at ±15 V power supply; easy adjustment of the level for each band, as well as the overall level (via the input buffer). 2. FILTER TYPES AND BASIC OPERATING PRINCIPLES Each filter is implemented as two cascaded Sallen–Key 2nd order (Butterworth) stages, resulting in a final 4th order LR4 filter. Topology: non-inverting Sallen–Key, optimal for NE5532. For all stages: Cascade gain: K ≈ 1.586 This provides a Q factor of 0.707 (Butterworth), which in combination gives a Linkwitz–Riley 4th order. 3. COMPONENT VALUES FOR FILTERS 3.1 Universal Parameters RC chain capacitors: 10 nF, film capacitors, tolerance ≤ 5% Resistors: metal-film, tolerance ≤ 1% The gain of each stage is set by feedback resistors: Rf = 5.9 kΩ Rg = 10 kΩ K ≈ 1 + (Rf / Rg) ≈ 1.59 The circuit should allow for the installation of a small capacitor (10–47 pF) in parallel with Rf (footprint provided) for possible stability correction (not mandatory to install in the first revision). 3.2 650 Hz Filters (Low-frequency boundary for MF) These are used for the division between W250 and MR130. LP650 — Low-frequency Filter 2nd Order R1 = 24.9 kΩ R2 = 24.9 kΩ C1 = 10 nF C2 = 10 nF Two stages: LP650 #1 and LP650 #2. HP650 — MF High-frequency Filter 2nd Order Same values: R1 = 24.9 kΩ R2 = 24.9 kΩ C1 = 10 nF C2 = 10 nF Two stages: HP650 #1 and HP650 #2. 3.3 2500 Hz Filters (Upper boundary for MF) These are used for the division between MR130 → MDT-12. LP2500 — High-pass MF Filter R1 = 6.34 kΩ R2 = 6.34 kΩ C1 = 10 nF C2 = 10 nF Two stages: LP2500 #1 and LP2500 #2. HP2500 — High-frequency Filter Same values: R1 = 6.34 kΩ R2 = 6.34 kΩ C1 = 10 nF C2 = 10 nF Two stages: HP2500 #1 and HP2500 #2. 4. OPERATIONAL AMPLIFIERS The NE5532 (dual op-amp, DIP-8 or SOIC-8) is used. A minimum of 4 packages (8 channels) for filters: NE5532 Function U1A, U1B LP650 #1, LP650 #2 (LF) U2A, U2B HP650 #1, HP650 #2 (Lower MF cut-off) U3A, U3B LP2500 #1, LP2500 #2 (Upper MF cut-off) U4A, U4B HP2500 #1, HP2500 #2 (HF) Additionally: U5 — input buffer / preamplifier (both channels) If necessary, an additional NE5532 (U6) for the balanced input (see section 6.2). All NE5532 should have local decoupling for power supply (see section 5.1). 5. CROSSOVER POWER SUPPLY AM4T-4815DZ DC/DC module is used: Input: 36–72 V, connected to the 48 V power supply for TPA3255 amplifiers. Output: +15 V / –15 V, up to 0.133 A per side. Maximum output capacitance: ≤ 47 µF per side (according to the datasheet). 5.1 Power Filtering Input (48 V): RC variant (simpler, acceptable for the first revision): R = 1–2 Ω / 1–2 W C = 47–100 µF (for 63 V or higher) LC variant (preferred for improved noise immunity): L = 10–22 µH C = 47–100 µF The developer may implement LC if confident in choosing the inductance and its parameters. Output +15 V and –15 V (general filtering): Electrolytic capacitor 10–22 µF per side 100 nF (X7R) per side to GND Local decoupling for NE5532 (REQUIRED): For each NE5532 package: 100 nF between +15 V and GND 100 nF between –15 V and GND Place as close as possible to the op-amp power pins (short traces). Additional local filtering for power lines: For each NE5532, decouple from the ±15 V main rails: Either 4.7–10 Ω resistor in series with +15 V and –15 V, Or ferrite bead in each rail. After this component, place local capacitors (100 nF + 1–4.7 µF) to ground. 6. INPUT TRACT: INPUTS, BUFFER, ADJUSTMENT 6.1 Unbalanced Input (RCA / Jack / Linear) The main mode is the unbalanced linear input, for example, RCA. Input tract structure: RF-filter and protection: Signal → series resistor Rin_series = 100–220 Ω After resistor — capacitor Cin_RF = 470–1000 pF to GND This forms a low-level RF filter and reduces high-frequency noise. DC-block (low-pass HP-filter): Capacitor Cin_DC = 2.2–4.7 µF film in series Resistor to ground Rin_to_GND = 47–100 kΩ Cut-off frequency — negligible in the audio range but removes DC. Input buffer / preamplifier (NE5532, U5): Non-inverting configuration. Input — after DC-block. Gain: adjustable, e.g., Rg_fixed = 10 kΩ (to GND through trimmer) Rf = 10–20 kΩ + footprint for trimmer (e.g., 20 kΩ) The gain should be in the range of 0 dB to +10…+12 dB. Possible configuration: Rg = 10 kΩ fixed Rf = 10 kΩ + 10 kΩ trimmer in series. This allows adjusting the overall level of the crossover according to the source and amplifier levels. Buffer output: A low-impedance output (after NE5532) This signal is simultaneously fed to the inputs of all filters: LP650 (LF) HP650 → LP2500 (MF) HP2500 (HF) 6.2 Balanced Input (XLR / TRS) — Optional, but laid out on the board The board should allow for a balanced input, even if it’s not used in the first revision. Implementation requirements: XLR/TRS connector (L, R, GND) or separate 3-pin header. Simple differential receiver on NE5532 (extra U6 package or use one channel of U5 if sufficient). Circuit: classic instrumentation amplifier or differential amplifier: Inputs: IN+ and IN– Output — single-ended signal of the same level (or slightly amplified), fed to DC-block and buffer (or directly to the buffer if integrated). Switching between balanced/unbalanced mode: Implement using jumpers / bridges or adapters: Either switch before the buffer, Or use two separate pads, one of which is unused. All balanced input grounds must be connected to the same AGND point as the unbalanced input to avoid ground loops. 7. LEVEL ADJUSTMENT OF BANDS (BEST METHOD) The level adjustment of each band (LOW, MID, HIGH) is required to match the sensitivity of the speakers and amplifiers. Recommended method: After each full filter (after LP650×2, MID-chain HP650×2 → LP2500×2, HP2500×2), install: A passive attenuator: Series: Rseries (0–10 kΩ, adjustable) Shunt: Rshunt to GND (10–22 kΩ, fixed or adjustable) For simplicity and reliability: Implementation on the board: For each band (LOW, MID, HIGH) provide: Pad for multi-turn trimmer 10–20 kΩ as a divider (between signal and ground) in the "level adjustment" configuration. If adjustment is not needed — install a fixed divider (two resistors) or simply use a jumper. It is preferable to use: For setup: multi-turn trimmers 10–20 kΩ, available on the top side of the board. Nominals for the initial configuration can be selected through measurements, but the PCB should have flexibility. This provides: Accurate balancing of band volumes without interfering with the filters; Flexibility for fine-tuning to the specific characteristics of the speakers. 8. INPUTS AND OUTPUTS OF THE CROSSOVER (FINAL) 8.1 Inputs 1× Unbalanced linear input (RCA or 3-pin header) 1× Balanced input (XLR/TRS or 3-pin header) — optional, but space must be provided on the board. Input impedance (unbalanced after RF-filter): 22–50 kΩ. The input tract must be implemented using shielded cables. 8.2 Outputs Outputs to amplifiers: Output Signal LOW OUT After LP650×2 (LF) MID OUT After HP650×2 → LP2500×2 (MF) HIGH OUT After HP2500×2 (HF) Each output: Series resistor 100–220 Ω (prevents possible oscillations and simplifies cable management). A nearby own AGND pad (ground output), so the signal pair SIG+GND runs together. Outputs should be compactly placed on 2-pin connectors (SIG+GND) or 3-pin (SIG+GND+reserve). 9. PCB DESIGN REQUIREMENTS 9.1 Board Number of layers: 2 layers Bottom layer: solid analog ground (AGND). 9.2 Component Placement Key principles: RC chains of each filter (R1, R2, C1, C2, Rf, Rg) should form a compact "island" around the corresponding op-amp. If elements are placed too far apart, the filter will not work correctly (calculated frequency and Q will shift). Feedback tracks (Rf and Rg) should be as short and direct as possible. The AM4T-4815DZ module should be placed: Far from the input buffer, Far from the first filter stages, If necessary, make a "cutout" in the ground under it to limit noise propagation. Place the input connector, RF-filter, and buffer on one side of the board, and the output connectors on the opposite side. 9.3 Ground The entire audio circuit uses one analog ground: AGND. Connect AGND to the power ground (48 V and amplifiers) at one point ("star"). The star should be implemented as: One point/pad where: The ground of the input, The ground of the filters, The ground of the outputs, The ground of the DC/DC. Avoid long narrow "ground" jumpers — use wide polygons with a single connection point. 9.4 Placement of Output Connectors Group LOW/MID/HIGH compactly. Each should have its own GND pad nearby. Route the SIG+GND pairs as signal pairs, avoiding large loops. 10. ADDITIONAL ELEMENTS: PROTECTION, TEST POINTS 10.1 Test Points (TP) Be sure to provide test points (pads): TP_IN — crossover input (after buffer) TP_LOW — LF filter output TP_MID — MF filter output TP_HIGH — HF filter output TP_+15, TP_–15, TP_GND — power control This greatly simplifies debugging with an oscilloscope. 10.2 Power Protection On the 48 V input — it is advisable to provide: Diode/scheme for reverse polarity protection (if possible), TVS diode or varistor for voltage spikes (optional). 10.3 Possible Stability Correction Pads for small capacitors (10–47 pF) in parallel with Rf in buffers and, if necessary, in some stages — in case of stability issues (this can be not installed in the first revision, but footprints should be provided). 11. BILL OF MATERIALS (BOM) Operational Amplifiers: NE5532 — 4 pcs (filters) NE5532 — 1–2 pcs (input buffer and balanced input) Total: 5–6 NE5532 packages. Resistors (1%, metal-film): 24.9 kΩ — 8 pcs 6.34 kΩ — 8 pcs 10 kΩ — ≥ 12 pcs (feedback, buffers, etc.) 5.9 kΩ — 8 pcs 22 kΩ — 1–2 pcs (input, auxiliary chains) 47–100 kΩ — several pcs (DC-block, input) 100 kΩ — 1 pc (if needed) 100–220 Ω — 4–6 pcs (outputs, RF, protection) 4.7–10 Ω — 2 pcs for each op-amp or group of op-amps (power filtering) — quantity to be clarified during routing. Trimmer Resistors: 10–20 kΩ multi-turn — one for each band (LOW, MID, HIGH) 10–20 kΩ — 1–2 pcs for the input buffer (overall gain adjustment). Capacitors: 10 nF film — 16 pcs (RC filters) 2.2–4.7 µF film — 1–2 pcs (input DC-block) 10–22 µF electrolytic — 2–4 pcs (DC/DC outputs) 1–4.7 µF (X7R / tantalum) — 1 pc for local power filtering (optional). 100 nF ceramic X7R — 10–20 pcs (local decoupling for each op-amp) 470–1000 pF — 1–2 pcs (RF filter on the input) 10–47 pF — optional for stability correction (Rf). Power Supply: AM4T-4815DZ — 1 pc Inductor 10–22 µH (if LC filter) — 1 pc R 1–2 Ω / 1–2 W — 1 pc (if RC filter). Connectors: Input (RCA + 3-pin for internal input) Balanced (XLR/TRS or 3-pin header) Outputs LOW/MID/HIGH — 2-pin/3-pin connectors. 12. TESTING RECOMMENDATIONS 12.1 First Power-up Apply ±15 V without installed op-amps. Check with a multimeter: +15 V –15 V No short circuits in the power supply. Install the op-amps (NE5532). Apply a sine wave of 100–200 mV RMS (signal generator). Check with an oscilloscope at TP: LP650 — should pass LF and roll off everything above 650 Hz. HP650 — should roll off LF, pass everything above 650 Hz. LP2500 — should roll off above 2500 Hz. **HP250 0** — should pass everything above 2500 Hz. 12.2 Phase Check The Linkwitz–Riley 4th order should give a flat frequency response when summed at the crossover points. This can be verified with REW/Arta. 12.3 Noise Check If there is noticeable "shshsh" or whistling: Check: Grounding layout (star) Placement and filtering of AM4T-4815DZ Presence and proper installation of all 100 nF and local filters. 13. FINAL RECOMMENDATIONS FOR BEGINNERS Do not rush, build the circuit step by step: input → buffer → one filter → test, then continue. Check component values at least twice before soldering. Filters should be routed as compact "islands" around the op-amp, do not stretch R and C across the board. Always remember the rule: "The feedback trace should be as short as physically possible." Before ordering the PCB, make a "paper prototype": print at 1:1, cut it out, place real components to check everything fits.

Power supply for 3.3V from a 2S LiPO using an XT30 connector

Haptic Glove Controller Board NUCLEO-F411RE based Fixed Servo Connections to match standard servo wiring Revised footprint of 2n3904s transistors since base and emitter footprint were swapped Larger power traces Swapped SDO and SDI of SPI Lines to the FPC connector so it matches with peripheral.

This circuit can take an analog input, control a DC gearmotor, sense its direction and cumulative number of revolutions, and turn on and off three LEDs, in whatever way it is programmed. It can be repeatedly reprogrammed through a connector on the PCB. Powered by six AA batteries, it economizes on power by disconnecting some components when they are not in use.

This project is a Switched-Mode Power Supply (SMPS) design. The design incorporates an AC DC Converter (NCP1203D100R2), polarized capacitors, resistors, diodes, connectors, a transistor, a transformer and an integrated circuit. #AC #DC #POWER #NCP1203 #project

This is a BLE to WiFi gateway Reference Design. It employs an ESP32 microcontroller and an STM32WB5MMGH6TR for BLE functionality. The design includes connectors, multiple capacitors, resistors, switches, and LEDs. USB Type-C is used for power and data. This could be used for IoT purposes in home automation or wireless sensor data transmission. #referenceDesign #edge-computing #espressif #stm #template #ble #reference-design

This project is an IoT development board based on the ESP32-H2-WROOM-03 module, featuring USB-C connectivity for power and communication. The board also includes two buttons, several decoupling capacitors, and a couple of connectors for peripheral connections. The onboard USB-to-UART bridge facilitates communication with a host device. #referenceDesign #esp32 #iot #esp32-h2 #project #template #reference-design

This project is an IoT development board based on the ESP32-H2-WROOM-03 module, featuring USB-C connectivity for power and communication. The board also includes two buttons, several decoupling capacitors, and a couple of connectors for peripheral connections. The onboard USB-to-UART bridge facilitates communication with a host device. #referenceDesign #esp32 #iot #esp32-h2 #project #template #reference-design

This is a BLE to WiFi gateway Reference Design. It employs an ESP32 microcontroller and an STM32WB5MMGH6TR for BLE functionality. The design includes connectors, multiple capacitors, resistors, switches, and LEDs. USB Type-C is used for power and data. This could be used for IoT purposes in home automation or wireless sensor data transmission. #referenceDesign #edge-computing #espressif #stm #template #ble #reference-design

This project is a Battery Management System (BMS) built around STMicroelectronics' STC3115AIQT battery monitor IC. It uses I2C for communication, features alarm management, and supports battery charging. The power supply, battery connection points, and debug interface are facilitated through connectors. #project #Template #charger #monitor #reusable #module #batterycharger #template #bms #STC3115 #stm

This project is an IoT development board based on the ESP32-H2-WROOM-03 module, featuring USB-C connectivity for power and communication. The board also includes two buttons, several decoupling capacitors, and a couple of connectors for peripheral connections. The onboard USB-to-UART bridge facilitates communication with a host device. #referenceDesign #esp32 #iot #esp32-h2 #project #template #reference-design

This project is an innovative audio amplifier design focused on delivering high-quality sound and performance for commercial applications. The design features a robust 220V AC input that undergoes careful transformation, rectification, and regulation to provide a stable power supply. Central to the project is an audio amplifier circuit engineered to deliver a reliable 20W output, ensuring optimal sound clarity and efficiency. To enhance usability and connectivity, the design incorporates premium audio connectors for seamless input and output integration. This project prioritizes safety, efficiency, and scalability, positioning it as an ideal solution for fairs, events, and other commercial audio applications. #AudioAmplifier #220VAC #20WOutput #AudioConnectors #CommercialAudio #HighFidelitySound

This project is a Battery Management System (BMS) built around STMicroelectronics' STC3115AIQT battery monitor IC. It uses I2C for communication, features alarm management, and supports battery charging. The power supply, battery connection points, and debug interface are facilitated through connectors. #project #Template #charger #monitor #reusable #module #batterycharger #template #bms #STC3115 #stm

This project is an IoT development board based on the ESP32-H2-WROOM-03 module, featuring USB-C connectivity for power and communication. The board also includes two buttons, several decoupling capacitors, and a couple of connectors for peripheral connections. The onboard USB-to-UART bridge facilitates communication with a host device. #referenceDesign #esp32 #iot #esp32-h2 #project #template #reference-design

This project is a Battery Management System (BMS) built around STMicroelectronics' STC3115AIQT battery monitor IC. It uses I2C for communication, features alarm management, and supports battery charging. The power supply, battery connection points, and debug interface are facilitated through connectors. #project #Template #charger #monitor #reusable #module #batterycharger #template #bms #STC3115 #stm

This project is a Battery Management System (BMS) built around STMicroelectronics' STC3115AIQT battery monitor IC. It uses I2C for communication, features alarm management, and supports battery charging. The power supply, battery connection points, and debug interface are facilitated through connectors. #project #Template #charger #monitor #reusable #module #batterycharger #template #bms #STC3115 #stm