security alarm circuit

Short Whip Antenna Tuner - Here is a circuit that will resonate a short whip antenna for the HF Bands.

ZL1BPU Rotator Controller - A very simple controller circuit, with fairly smart performance! The ZL1BPU Rotator Controller has been designed as an add-on unit for the popular Kenpro KR-400 and Yaesu G-400 rotators. The controller consists of a small circuit board which fits inside the rotator control box (see picture).

Emtech ZM-2 Antenna Tuner Kit - The Emtech ZM-2 Antenna Tuner is a nifty little portable transmatch for QRP (low power). It utilizes the well-known Z-match circuit, which is especially useful for balanced antennas (like dipoles and loops).

NM-ARTS - Amateur Radio Technical Society - A hardware and software project group to support learning and creation radio circuits, general electronics, and uProcessor control systems

K6XX CW Indicator Kit - The purpose of this circuit is to light a LED in your radio when you tune to within +- 20hz of a cw signal. This makes for easy tuning of a cw signal by eye rather than by ear

PSK31 Interfacing - PSK31 basics and radio to pc soundcard interface circuits, radio to soundcard, soundcard to radio and pc serial port to radio

Is HF propagation reciprocal - Some test circuits using the ACE-HF System Simulation & Visualization software, about reciprocal propagation on HF bands by NW7US

RF Circuit design basics - Ebook by Akira Matsuzawa Tokyo Institute of Technology, Building blocks in RF system and basic performances, Device characteristics in RF application , Low noise amplifier design, Mixer design and Oscillator design

Far Circuits - FAR Circuits is exclusively a manufacturer of Printed Circuit Boards for electronic projects that are used by the Amateur Radio and electronic hobby enthusiast.

Shortwave Converter - This is a simple circuit that when placed near an ordinary AM broadcast radio will allow you to receive international shortwave broadcasts in the 5-6 MHz band

DesignWorks - Commercia, productive and easy-to-use electronic circuit schematic drawing tool Featuring full hierarchical design, standard and custom netlist formats, extensive symbol libraries, scripting and customization features and much more.

ViPEC Network Analyzer - This program intended for electronic circuit analysis (mainly for Linux). ViPEC is a powerful tool for the analysis of high frequency, linear electrical networks.

Target 3001 PCB Design - Represents a new generation of CAD/CAE software for circuit design. Has been created to meet the requirements of professional design engineers.

Qucs - Quite Universal Circuit Simulator Priority listing - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit. After that simulation has finished you can view the simulation results on a presentation page or window. Run on Linux.

AA Battery Solar Charger - This almost trivial circuit may be used to charge a pair of AA or AAA sized rechargeable battery cells from sunlight.

TANKIT Priority listing - A free design aid for vacuum tube linear RF power amplifiers. Determine plate circuit operating parameters and design pi or pi-L tanks quickly and easily.

Medium Frequency Amplifier Circuits Compared - Mark Connelly, WA1ION article on Medium Frequency Amplifier Circuits in PDF format, include some RF amplifier schematics

Audio processor for SSB transceiver - This circuit consists of microphone amplifier and a high pass filter. Suitable to improve signal readability.

A low cost UHF/VHF duplexer - Duplexers for dual band radio are usually high pass filter and low pass filter combined in the same box. This circuit is a design within a cost of US$10.

FM Morse Code Keyer - A simple circuit which will generate a 700 Hz tone into any FM transceiver allowing an amateur to practice CW with another amateur on a 2 meter simplex frequency.

20 Amp power supply - A 13.8 volt 20 Ampere power supply project

Universal QRP Transmitter - Here's the homebrew Universal QRP transmitter adapted from work by Wes Hayward - W7ZOI. The circuit originally appeared in QRP Classics published in 1980 by the ARRL

Signal Generation Solution - Build an inexpensive RF signal generator

A reliable VOX PTT circuit - This VOX PTT has been designed with Echolink in mind, but it will work equaly as well with repeaters

Fun With Tubes - Dedicated to passing on and preserving knowledge of vacuum tube circuits and techniques