JLCPCB Blog

Basics & Tips

Arduino LED Multiplexing Tutorial: Control More LEDs with Fewer Pins

The Arduino Uno is a powerful tool for prototyping, but driving multiple LEDs directly quickly exhausts its 20 GPIO pins and its 200 mA absolute maximum package current limit. To bypass these hardware bottlenecks, engineers and hobbyists use LED multiplexing to scale display outputs efficiently without upgrading the microcontroller. In this guide, you will learn the core principles of LED matrix scanning, Charlieplexing, refresh timing, ghosting fixes, and practical Arduino code without relying on any......

Jun 23, 2026

Components & Sourcing

NPN vs PNP Transistor: Key Differences, Working Principles, and Applications

Both NPN and PNP transistors are Bipolar Junction Transistors (BJTs) used for switching and amplification. They share the same three-layer construction but operate with opposite current and voltage polarities. Mixing up the two is a common source of design errors, from a relay that never switches to a high-side load that stays permanently on. This guide breaks down the structure, symbols, switching behavior, and selection criteria you need to pick the right transistor for your circuit. NPN vs PNP Tran......

Jun 23, 2026

PCB Fabrication Case

PiBrick Pocket-CM5: A Compact Raspberry Pi CM5 Handheld PC Built with JLCPCB

Key Takeaways The piBrick Pocket-CM5 is a fully functional, smartphone-sized Raspberry Pi CM5 handheld PC with a physical QWERTY keyboard, AMOLED display, and M.2 NVMe SSD The project utilizes JLCPCB's 4-layer PCB fabrication with controlled impedance (90-ohm for USB, 100-ohm for PCIe/MIPI DSI) to maintain signal integrity Designed using EasyEDA and fabricated by JLCPCB, the project was submitted to the EasyEDA Spark program, successfully securing parts and materials sponsorship for its development. J......

Jun 23, 2026

Components & Sourcing

Ceramic Capacitor Types Explained: C0G, X7R, X5R, Y5V and How to Choose

Two ceramic capacitors can share the same capacitance value, the same voltage rating, and the same footprint, yet behave nothing alike on a powered board. The reason is the dielectric, not the number on the label. Ceramic capacitor types are defined by the dielectric, captured in codes like C0G, X7R, X5R, and Y5V. This guide decodes those codes, compares the dielectric classes, explains the DC bias and aging effects that catch designers off guard, and gives you a practical way to pick the right part f......

Jun 22, 2026

Basics & Tips

Op Amp Symbol Explained: Pinout, Polarity, and Power Pins

The op amp symbol is one of the most common shapes in analog schematics: a triangle with two inputs and one output. Reading it correctly, knowing which pin is inverting, which is non-inverting, and how power connects, is the first skill needed before building any amplifier circuit. Standard op amp symbols include a non-inverting input, an inverting input, an output, and power supply connections that may be shown or hidden depending on schematic style. The common symbol convention uses a triangle with ......

Jun 22, 2026

Flexible PCBs

Design Guidelines for Flex PCB Panels on JLCPCB

When placing orders for flexible PCBs (FPCs) on JLCPCB, several key points must be noted. Unlike rigid PCB panels, which often use mouse bites or V-cuts for depanelization, FPC panels require bridge (tab) connections. Requirements for Flex PCB Panels on JLCPCB FPC panelization differs significantly from rigid boards. Proper design ensures efficient manufacturing, high yield, and compatibility with SMT assembly. Key requirements are as follows: Internal Board Spacing: 2 mm (standard); preferably 3 mm w......

Jun 22, 2026