A complete guide to RJ-11, RJ-14, RJ-25, RJ-48, and RJ-9 connectors with color-coded diagrams and technical descriptions. RJ-48 – E1 and T1 Plug (8P8C) Connector Type: 8P8C (8 positions, 8 conductors) Color Code: Orange, Green, Blue, Brown, White, Black Application: Used in digital telecommunications for T1/E1 lines in carrier networks and PBX systems. Pin Functions: Each pair (1–2, 3–4, 5–6, 7–8) carries a separate tip and ring signal for high-speed data or voice channels. Standard: ANSI/TIA-568-B RJ-25 – 6P6C Plug Connector Type: 6P6C (6 positions, 6 conductors) Color Code: White, Black, Red, Green, Yellow, Blue Application: Designed for multi-line telephone systems supporting up to three independent phone lines. Pin Functions: Pairs (1–2), (3–4), and (5–6) each carry a separate line (Tip/Ring). Usage: Found in business telephony and legacy PBX installations. RJ-14 – 6P4C Plug Connector Type: 6P4C (6 positions, 4 conductors) Color Code: White, Black, Red, Green Application: Used for dual-line residential or office telephones. Pin Functions: Pins 1–2 for Line 1 (Tip/Ring), Pins 3–4 for Line 2 (Tip/Ring). Note: Compatible with standard RJ-11 jacks when only one line is used. RJ-11 – 6P2C Plug Connector Type: 6P2C (6 positions, 2 conductors) Color Code: White, Red Application: The most common connector for single-line analog telephone service worldwide. Pin Functions: Pin 1 = Tip (T), Pin 2 = Ring (R) – carries the voice signal and power for the phone. Compatibility: Widely used in home phones, fax machines, and modems. RJ-9 – 4P4C Plug (Inside the Handset) Connector Type: 4P4C (4 positions, 4 conductors) Color Code: Black, Red, Green, Yellow Application: Connects the handset to the telephone base, carrying microphone and speaker signals. Pin Functions: Pin 1 (Black): Ground / MIC return Pin 2 (Red): Microphone (MIC) Pin 3 (Green): Speaker (SPKR) Pin 4 (Yellow): Ground / SPKR return Internal Circuit: Often includes a ~500Ω resistor between MIC and SPKR to prevent feedback oscillation.

A detailed guide to the pin configuration and function of standard SIM cards (including mini, micro, and nano variants). Sim Card ┌─────────────┐ │ 1 5 │ │ 2 6 │ │ 3 7 │ │ 4 8 │ └─────────────┘ Connector at the card Pin Configuration & Description Pin Description 1 [VCC] +5V or 3.3V DC power supply input Provides operating voltage to the SIM chip. 2 [RESET] Card reset, used to reset the card's communications (optional) Sends a reset signal to restart communication protocol. 3 [CLOCK] Card clock Synchronizes data transfer between the mobile device and SIM card. 4 [RESERVED] AUX1, optionally used for USB interfaces and other uses Not used in standard GSM/UMTS/LTE SIMs; reserved for future or specialized applications. 5 [GND] Ground Common ground reference for all signals. 6 [VPP] +21V DC programming voltage input (optional) Used during manufacturing to program the SIM chip; not active in normal operation. 7 [I/O] Input or Output for serial data (half-duplex) Bidirectional data line for exchanging information between the phone and SIM. 8 [RESERVED] AUX2, optionally used for USB interfaces and other uses Reserved for future use or special applications such as smart card emulation.

Complete Guide to USB 2.0, 3.0, and 3.1 (USB-C) Connectors "Comprehensive pinout diagrams and technical descriptions for all major USB connector types, including Standard-A, B, Mini, Micro, and USB-C." This web-based reference provides a detailed breakdown of USB connector pin configurations , signal functions, voltage levels, and color coding across generations: USB 2.0, USB 3.0, and USB 3.1 (Type-C) . All information follows official specifications from the USB Implementers Forum (USB-IF) . Ideal for engineers, technicians, hobbyists, and students working with embedded systems, DIY electronics, or device repair. What Is USB? Universal Serial Bus (USB) is a standardized interface for connecting peripherals to computers and mobile devices. It supports: Data transfer Power delivery (up to 240W in USB PD) Device charging Hot-swapping Each USB version introduces new features: USB 2.0 : Up to 480 Mbps USB 3.0 : Up to 5 Gbps USB 3.1 Gen 2 : Up to 10 Gbps USB 3.2 / USB4 : Up to 40 Gbps The physical connectors vary by type and generation, but all follow strict pin assignments. USB Connector Types Overview Connector Pins Use Case USB 2.0 A/B 4 pins Hosts, printers, keyboards Mini/Micro USB 2.0 5 pins Older phones, cameras USB 3.0 A/B 9/11 pins High-speed data, external drives Micro USB 3.0 10 pins Smartphones, tablets USB 3.1 C (USB-C) 24 pins Reversible, high-power, fast data Note: USB-C supports reversibility , dual-role operation , and Power Delivery (PD) . USB 2.0 – Standard A & B Connectors Standard A: Standard B: ┌─────────┐ ┌─────────┐ │ 4 3 2 1 │ │ 1 2 │ └─────────┘ └─────────┘ ↑ ↑ Plug View Plug View Pin Configuration (4-Pin) Pin Signal Color Code Function 1 VCC (+5V) Red Power supply (up to 500mA) 2 Data - (D-) White Differential data pair (-) 3 Data + (D+) Green Differential data pair (+) 4 Ground Black Signal and power return Full-duplex communication using differential signaling No ESD protection on host side? Use TVS diodes! Mini/Micro USB 2.0 – Standard A & B Standard A: Standard B: ┌───────┐ ┌───────┐ │ 1 2 3 4 5 │ │ 1 2 3 4 5 │ └───────┘ └───────┘ Pin Configuration (5-Pin) Pin Signal Function 1 VCC (+5V) Power supply 2 Data - (D-) USB 2.0 data negative 3 Data + (D+) USB 2.0 data positive 4 None Host detection: connected to ground in hosts, open in devices 5 Ground Common ground Pin 4 enables automatic detection of host vs. slave Used in older smartphones, GPS units, and digital cameras USB 3.0 – Standard A & B Connectors USB 3.0 A (9-Pin) Plug View: ┌─────────────┐ │ 5 6 7 8 9 │ │ 4 3 2 1 │ └─────────────┘ Pin Signal Function 1 VCC (+5V) Power supply 2 D- USB 2.0 data negative 3 D+ USB 2.0 data positive 4 GND Power ground 5 RX2- USB 3.0 receive line (-) 6 RX2+ USB 3.0 receive line (+) 7 GND Signal ground 8 TX2- USB 3.0 transmit line (-) 9 TX2+ USB 3.0 transmit line (+) Backward compatible with USB 2.0 Speed: Up to 5 Gbps (SuperSpeed) USB 3.0 B (11-Pin) Plug View: ┌─────────────┐ │ 9 8 7 6 5 │ │ 10 11 │ │ 4 3 │ └─────────────┘ Pin Signal Function 1 VCC (+5V) Power supply 2 D- USB 2.0 data negative 3 D+ USB 2.0 data positive 4 GND Power ground 5 TX2- USB 3.0 transmit line (-) 6 TX2+ USB 3.0 transmit line (+) 7 GND Signal ground 8 RX2- USB 3.0 receive line (-) 9 RX2+ USB 3.0 receive line (+) 10 DPWR Power provided by device (e.g., bus-powered hub) 11 GND Return for DPWR Rarely used; replaced by USB-C in modern devices Micro USB 3.0 (10-Pin) Plug View: ┌─────────────────────┐ │ 1 0 9 8 7 6 │ │ 5 4 3 2 1 │ └─────────────────────┘ Pin Signal Function 1 VCC (+5V) Power supply 2 D- USB 2.0 data negative 3 D+ USB 2.0 data positive 4 ID OTG identification (host/device role) 5 GND Power ground 6 TX2- USB 3.0 transmit line (-) 7 TX2+ USB 3.0 transmit line (+) 8 GND Signal ground 9 RX2- USB 3.0 receive line (-) 10 RX2+ USB 3.0 receive line (+) Used in early smartphones and tablets before USB-C adoption Supports On-The-Go (OTG) mode USB 3.1 Type-C (24-Pin) – Reversible Connector Plug View (Top Side): ┌────────────────────────────┐ │ 1 2 3 4 5 6 7 8 9 10 11 12 │ └────────────────────────────┘ │ 13 14 15 16 17 18 19 20 21 22 23 24 │ └────────────────────────────┘ Pin Configuration (24-Pin) Pin Signal Function 1 GND (A1) Ground 2 TX1+ (A2) SuperSpeed transmit (+) 3 TX1- (A3) SuperSpeed transmit (-) 4 Vbus (A4) +5V power supply 5 CC1 (A5) Configuration Channel (detects orientation, power roles) 6 D+ (A6) USB 2.0 data positive 7 D- (A7) USB 2.0 data negative 8 SBU1 (A8) Sideband use (for video/audio, alternate modes) 9 Vbus (A9) +5V power supply (second path) 10 RX2- (A10) SuperSpeed receive (-) 11 RX2+ (A11) SuperSpeed receive (+) 12 GND (A12) Ground 13 GND (B12) Ground (symmetric side) 14 RX1+ (B11) SuperSpeed receive (+) 15 RX1- (B10) SuperSpeed receive (-) 16 Vbus (B9) +5V power supply 17 SBU2 (B8) Sideband use 18 D- (B7) USB 2.0 data negative 19 D+ (B6) USB 2.0 data positive 20 CC2 (B5) Configuration Channel (backup) 21 Vbus (B4) +5V power supply 22 TX2- (B3) SuperSpeed transmit (-) 23 TX2+ (B2) SuperSpeed transmit (+) 24 GND (B1) Ground Fully reversible plug Dual-role data flow (host/device) Supports USB Power Delivery (up to 240W) Supports DisplayPort and HDMI via Alternate Mode Design Tips for Engineers Always route D+/D- as differential pairs with controlled impedance (~90Ω) Keep Vbus trace short and wide for better current handling Use TVS diodes on D+/D- lines for ESD protection Add pull-up resistors on CC pins for proper negotiation Follow USB-IF compliance guidelines for certification Standards Compliance USB 2.0 : USB-IF Specification 2.0 USB 3.0 : USB 3.0 Specification (Rev. 1.0) USB 3.1 : USB 3.1 Specification (Rev. 1.0) USB-C : USB Type-C Specification (Rev. 2.1) All modern devices must comply with these standards for interoperability.