Operational Amplifier (Op-Amp) Beginner's Guide: From Theory to Practice
This beginner guide explains operational amplifiers from fundamentals to practical use. It covers op-amp types, open-loop operation as a comparator, and negative feedback for linear amplification. Key circuits—voltage follower, non-inverting, and inverting amplifiers—are analyzed using virtual short and virtual open concepts, with gain formulas and common pitfalls. It provides selection guidance, essential DC/AC/bandwidth parameters, and hands-on breadboard lab experiments using LM358. Readers gain the ability to analyze entry-level op-amp circuits, avoid typical mistakes, and build and test basic amplifier circuits with confidence.
Open Source 24V3A Flyback Power Supply Based on UC3842, with Transformer Parameter Calculation
An open-source 24V 3A flyback switching power supply design for 85–265VAC input, achieving 87.4% peak efficiency. Based on UC3842 with synchronous rectification, it provides schematics, PCB files, transformer calculations and specifications, and PSIM simulation models. Test data shows 83–87% efficiency, 1.81W no-load consumption, and ripple around 560–730mV. Full-load thermal performance requires heatsinking.
Flyback Power Supply Design: Parameter Calculation, Component Selection & Transformer Winding Guide
This article presents a complete design procedure for a 72W flyback switching power supply (24V/3A) with universal 85-265VAC input. It provides step-by-step calculations for rectifier bridge, input filter, transformer magnetizing inductance and turns, wire selection with skin effect, MOSFET and output diode ratings, output capacitor, and RCD snubber. Key trade-offs such as frequency vs. efficiency, flux density selection, and core AP value are explained. The article also details practical transformer winding, including air gap adjustment and leakage inductance measurement, enabling readers to replicate the design.
Open-Source USB 10 Gbps Hub with 2.5 Gbps Ethernet & TF/SD Card Reader (VL822+RTL8156BG+GL3224)
An open-source USB-C dock integrates four 10Gbps USB-A ports, 2.5G Ethernet, and TF/SD readers using VL160, VL822, RTL8156BG, GL3224. It accepts 4-20V input, buck-boosts to 5.1V with up to 9.5A, supporting PD fast charging. Tests show USB read/write 969.65/912.65 MB/s, Ethernet 2089/2497 Mbps, card read 93.04 MB/s, efficiency up to 91.79%. Schematics, PCB files, and replication notes are provided.
Open-Source Smart Electronic Load Based on CH32V307, Embedded Competition Project Open Source
An open-source smart electronic load based on the CH32V307VCT6 microcontroller is presented, developed as a national second-prize entry in the 2023 embedded design competition. It supports constant current, voltage, resistance, and power modes, with 100V/10A/200W ratings. Schematics, PCB files, source code, and reports are freely available for learning and reference.
EG1151 High-Power Synchronous Buck-Boost Power Module (Supports Type-C PD Fast Charging) Open Source
An open-source high-power adjustable buck-boost DC-DC module based on the EG1151 chip is introduced, using fully domestic components. It supports Type-C PD3.1 up to 48V, XT60, and DC5.5 inputs, up to 63V and 20A, with overcurrent and over-temperature protection. Measured peak efficiency is 96.8%, though sustained current is about 18A. Schematics, PCB files, and 3D-printed enclosure models are provided.
What is dB? How to Calculate dBm, dBc, dBi, and dBd, and What Are Their Differences?
This article explains dB as a logarithmic unit for ratios, using 10log for power and 20log for voltage/current. It defines dBm against 1 mW, dBc against carrier power, dBi against isotropic antenna, and dBd against dipole (dBi minus 2.15). Understanding these units and calculations enables accurate analysis and design of electronic and communication systems.
Open-Source 140W+65W Buck-Boost PD3.1 Fast-Charging Module (2C+1A Ports), IP6557+IP6538,
An open-source 205W buck-boost fast-charging module based on IP6557 and IP6538 is presented, offering 140W on one Type-C port with PD3.1 support and 65W on the second Type-C and Type-A ports. Maximum conversion efficiency reaches 96.7%. Full documentation and design files are provided, enabling users to replicate a cost-effective charger.
A Simple Unboxing and Review of EastTester(中创) ET4410 Desktop Digital LCR Meter
The article reviews the EastTester ET4410 LCR meter, purchased for 1,199 yuan. It outlines key specifications, including 10Hz-100kHz frequency, 0.2% basic accuracy, DCR and electrolytic capacitor modes, TFT display, and calibration functions. Practical tests show accurate measurements for resistors, capacitors, and inductors, though low-resistance readings are limited. A list sweep mode bug is identified, with a firmware update provided. Readers gain cost-performance insights, usage guidance, and awareness of measurement limitations when choosing this instrument.
STM32 based OLED screen driver with software or hardware I2C support (HAL library)
This article presents a complete STM32G474 HAL library driver for 0.96-inch SSD1306 OLED displays with 4-pin I2C interface, supporting both hardware and software I2C via simple macro configuration. It enables displaying English, integers, floating-point numbers, Chinese characters, images, binary and hex values, plus drawing points, lines, rectangles, circles, ellipses, and triangles with multiple fonts. Step-by-step STM32CubeMX setup instructions for both I2C modes are included, making integration straightforward.
Synchronous Rectification Buck-Boost Digital Power Supply Based on STM32
This article presents an open-source four-switch Buck-Boost digital power supply based on STM32G474, supporting Type-C PD and DC input up to 48V10A and 450W. It includes schematic, PCB, firmware, and 3D model files. The design offers adjustable output, OLED display, protections, and host monitoring, achieving up to 94.3% efficiency and low ripple. Users can access calculations and source code.