This blog contains electronic, amateur radio, and embedded system projects, which I did during my free time. Unless otherwise noted, all the articles and projects described on this blog are based on my original designs.
In today's software development landscape, local Large Language Models (LLMs) offer unprecedented privacy, zero latency, and freedom from subscription fees. While I generally avoid purely " vibe coding " for my projects, having robust inline code completion and chat directly integrated into IDEs speeds up development significantly. However, consumer GPUs with high VRAM often cost enough that…
The primary objective of the Tiny Basic for Arduino project is to replicate that nostalgic C64 style programming environment utilizing modern, low-power MCU platforms. Present-day microcontrollers offer significantly higher processing power and memory capacity than the vintage systems of yesteryear, whilst being available at a fraction of the cost. I envisioned an environment where students and…
The TD4 is a famous 4-bit CPU featured in the book How to Build a CPU by Kaoru Tonami . The book focuses on constructing a functional processor entirely from basic 74-series TTL logic ICs. While the book is unfortunately only available in Japanese, a friend from Japan sent me a copy along with a TD4 PCB. I believe the PCB is based on the open-source design files available on BG5DIW's GitHub…
The TDA2005 is a very popular audio amplifier chip that many of us have used for years in car stereos and home DIY amplifiers. While it is mainly built to amplify AF signals, its internal design is actually strong enough to be used for other interesting projects like this DC-to-DC converter. By using the two amplifier channels inside the chip to create a high-frequency signal, we can turn the IC…
I found the ZZRX-40 receiver while going through some old issues of QEX magazine . Designed by Craig Johnson (AA0ZZ) , this is a very simple and easy-to-build 40m direct conversion receiver. Even though it is a simple circuit, it performs quite well for its size. Prototype version of extended ZZRX-40 receiver. For this project, I decided to make my own PCB design because I wanted to use components…
I recently received a DIY two-tube FM receiver kit from one of my Chinese component suppliers for review. The circuit is elegantly simple, designed around a 1A2 heptode and a 2P2 pentode . The kit includes all the necessary components for the build, featuring a single-sided FR4 PCB with dimensions of 100mm × 100mm. Assembled PCB with tubes. The primary hurdle when starting this project was the…
For an amateur radio operator, having a real-time dashboard is essential for monitoring band conditions and identifying DX opportunities. While several solutions exist, I recently completed a project centered on OpenHamClock , an open-source, web-based successor to Elwood Downey’s (WB0OEW) original HamClock . My goal was to move beyond simply opening a browser tab and instead create a dedicated,…
This project began with a simple idea: to build a fully functional digital desk clock using only classic CMOS logic ICs that are still readily available in local electronics markets. No microcontrollers, no firmware, no programmable logic - just counters, flip-flops, logic gates, and seven-segment decoders doing exactly what they were designed to do. The result is a 24-hour digital clock powered…
The BG7TBL FA-5 frequency counter has become recognized as an excellent choice for experimenters and radio enthusiasts, offering high-spec performance comparable to branded units. But it remains remarkably accessible due to its low cost. FA-5 Frequency counter. The FA-5 has powerful hardware. However, most existing control applications lack a good user experience. Many of them rely on scripting…
This is a simple surge arrester array that I made in my free time. Built using readily available components, the array provides effective shielding against lightning-induced surges and static discharges that can damage sensitive transmitting and receiving systems. The primary goal of this project was to create a robust, low-loss surge protection unit that can handle multiple RF lines…
The Arduino Mini Amplifier is a compact audio system that merges vintage analog and modern digital components. It combines a Philips TDA8425 audio processor and an Arduino Nano , supporting Bluetooth and line-in audio, spectrum analysis, stereo modes, and software-controlled tone adjustment. Finished prototype of the Arduino Mini Amplifier. The Arduino Mini Amplifier is organized into six major…
For some time, hobbyists have relied on dedicated sound generator ICs, such as the UM3561 , UM3562 to build compact alarm and siren circuits. Unfortunately, this device is becoming increasingly difficult to find in the market. The manufacturer of the chip, United Microelectronics Corporation (UMC), is still around. However, they are no longer producing the UM3561 or UM3562. As part of a fun…
Managing liquid levels in tanks is a common challenge across home, agricultural, and industrial automation systems. Whether dealing with a rooftop water tank or a chemical reservoir in a processing plant, maintaining the correct fluid level is crucial to prevent overflow, avoid dry-run damage to pumps, and reduce unnecessary power consumption. To address this challenge, we have designed a compact…
Ecowitt2APRS is a new open-source Linux service that I have been working on for the past few weeks. This project is designed to seamlessly integrate weather data from Ecowitt compatible professional weather stations into the global Automatic Packet Reporting System Internet Service (APRS-IS) network, transmitting this information in the standardized format of APRS weather packets. APRS, an amateur…
When it comes to automation and control systems, there's often a need for multiple digitally controlled output terminals with high-voltage handling capabilities. Many existing modules are bulky, expensive, or require numerous additional components to function. To address this gap, I've developed a fully open-source, USB-controlled 24-channel high-voltage driver. This device provides precise,…
This blog post discusses the engineering design, construction, and performance evaluation of a 4-element Yagi-Uda antenna specifically optimized for the 2-meter amateur radio band, focusing on the frequency range of 144MHz to 145.5MHz. The project was initiated to establish strong and reliable communication with distant VHF repeaters of the RSSL ( Radio Society of Sri Lanka ), which are located…
This project focuses on a simple yet powerful FM stereo tuner module. The core component of the module is RDA5807M , a single-chip broadcast FM stereo tuner that has gained popularity among designers in recent years due to its high level of integration. This integration significantly reduces the need for external components, simplifying circuit design. The RDA5807M supports a wide FM band,…
The Sony ICF-SW7600GR , a well-known portable shortwave receiver, has built a solid reputation for its performance and reliability. I purchased this receiver 20 years ago, and it is likely the last portable shortwave receiver manufactured by Sony . I primarily use it for shortwave listening, and it has functioned continuously for two decades. However, like all electronic devices, it is subject to…
Pink noise is an essential tool in audio testing, widely used for analyzing speaker systems, room acoustics, and crossover networks. Unlike white noise, which has equal energy across all frequencies, pink noise features equal energy per octave, making it ideal for audio response testing. This characteristic ensures that pink noise offers a flat frequency response when analyzed on a logarithmic…
The LM386 is a low-voltage audio power amplifier designed by National Semiconductor , which is now part of Texas Instruments . Introduced in 1983, it has been widely used in various audio applications, such as amplifying signals in small radios, portable speakers, and other low-power audio equipment. This compact device integrates all the essential components of a basic audio amplifier circuit,…
Simtelic Music Module is a user-programmable module that uses RTTTL data to store and play melodies. EL0003 - Programmable music module. RTTTL , which stands for Ring Tone Text Transfer Language , was created to provide a simple, text-based format for sharing ringtones on early mobile phones. Developed by Nokia , it quickly became popular due to its compact size and compatibility with text…
In this blog post, we will walk you through the process of developing a monolithic kernel call tinyOS from scratch by following tutorials from JamesM's and Bran's Kernel Development guides. This includes setting up a cross-compilation toolchain, writing assembly and C code for the kernel, creating an ISO image with GRUB , and testing it in a virtual machine (VM) using VirtualBox . Since some…
The HX711 is a versatile integrated circuit (IC) designed for precision analog-to-digital (A/D) conversion, particularly suited for strain gauge load cell applications. It features a 24-bit A/D converter with a differential input stage capable of handling both single-ended and differential input signals. Additionally, this device offers adjustable gain amplification to accommodate various load…
Have you ever faced the frustration of dealing with an overflowing tank or a pump running dry? These unexpected events can result in costly damage and inconvenience. A reliable floater switch alarm system can provide early warnings, allowing you to take prompt action and prevent further issues. This project guides you through building a do-it-yourself floater switch alarm system using a PIC12F508…
RDS ( Radio Data System ) is a communication protocol standard used for embedding small amounts of digital information in traditional FM radio broadcasts. It enables radio stations to transmit data such as station identification, program information, and traffic updates. To capture and decode RDS data, one method involves using a Software Defined Radio (SDR) along with GNU Radio and RFtap . GNU…