DIY Antennas, QRP, SDR & Ham Radio Projects from VU3DXR
The Circuits category focuses on stand‑alone electronic building blocks that power your radio and audio projects: amplifiers, oscillators, filters, keyers, indicators, test jigs, and more. Instead of full transceivers or big systems, you’ll find focused designs like microphone preamps, push‑pull HF linear amplifiers with IRF510, regenerative receivers, short‑wave transmitters, low‑battery indicators, and timing circuits
Discover how to build a Logarithmic Audio Compressor circuit for smooth, natural-sounding audio. This guide features a high-performance schematic using precision op-amps and log-antilog transistors to prevent distortion while maintaining consistent signal levels for amateur radio and pro-audio projects.
Learn how to build a simple and effective Audio Clipper Circuit using BC547 transistors and 1N914 diodes. This DIY guide covers schematic details, component selection, and how to prevent overmodulation in amateur radio transmitters for clearer, peak-limited audio.
Learn how to build a compact, high-sensitivity Miniature FM Transmitter with this DIY electronics guide. Featuring a simple transistor-based schematic and an electret microphone, this project is perfect for beginners exploring RF circuits and wireless audio.
The circuit shared here is a Microphone Preamplifier with Audio Peak Limiter, often used in audio recording, amateur radio, or intercom systems. It amplifies weak microphone signals and includes peak clipping diodes to prevent signal distortion from loud inputs. Looking to boost your microphone signal while keeping audio distortion in check? This two-stage transistor microphone […]
Build a high-sensitivity DIY 3-Transistor FM Bug Transmitter using a piezo microphone. This step-by-step guide includes a stable schematic, BC547 transistor tips, and frequency tuning advice for crystal-clear long-range audio monitoring.
There is something magical about hearing your own voice or music coming through a vintage tube radio from across the room—or across the neighborhood. While many low-power “flea” transmitters struggle with range, this 3-Watt AM monster brings some real “punch” to the Medium Wave band.
In this project, we’re stepping up the power. Using the classic BD139 transistor and a rock-steady crystal oscillator, we’ll build a transmitter that balances simplicity with performance. Whether you’re a Part 15 enthusiast or just want to experiment with AM modulation, this circuit is the perfect way to become your own local broadcaster. Let’s get on the air!
Build a simple 40 m CW transmitter using a 2N2222 and 7 MHz crystal oscillator — a minimalist QRP design with keyed oscillator and low-pass filter for clean HF Morse transmission.
If you’re a radio electronics enthusiast or hobbyist, building a Simple FM transmitter using readily available components like BC547 transistors can be both fun and educational. This compact circuit transmits voice signals captured via an electret microphone to a standard FM radio receiver, making it perfect for short-range audio transmission projects. Simple FM Transmitter – […]
Do you love electronics and want a fun, beginner-friendly project? Build a two transistor radio! This classic DIY project, featuring simple components, gained popularity years ago and still teaches radio technology effectively. Let’s explore how you can create your own two transistor radio easily. What is a Reflex Circuit? A reflex circuit cleverly reuses one […]
Maximize performance with minimal parts! Discover how the reflex circuit “recycles” its transistor to boost signal strength, making it the perfect DIY project for radio experimenters.