security alarm circuit

Simple active antenna - This circuit shows an active antenna that can be used for AM, FM, and shortwave

LU9DPD Daniel - Homebrew, antenas, balunes, expediciones, circuitos, electrónica, torres, fotos y relatos, todo referente a radioafición, radioaficionados y radioamateur

Antique Radio Schematics - Specializes in antique radio schematics, circuit diagrams and service data for vintage tube radios. Carries information for American, Canadian and European antique radios.

Washington State Army MARS - Emergency Communications Support - FEMA, DOMS, and Homeland Security communications resources. Health and Welfare radiograms.

Ham Radio India - Gateway to Indian Radio Amateurs. Resource features Indian amateur news, photos, circuits, articles, downloads, message boards and discussion forums.

QRZ.RU Russian HamRadio Server - Free Russian hamradio server special for radiofanats from CIS. Search engine on callsigns, electronic circuits and hamradio programs in www powered with knowledge base.

Laipac Technology Inc. - We are committed to constantly improving our solutions in areas of GPS System, GPS Receivers, GPS Antennas, GPS Dataloggers, RF Modules, Wireless Security Systems, Automatic Vehicle Location (AVL) for real time and passive tracking

Morse Tutor - Morse Tutor is a DOS based program written in C++. It can be used to practice morse code. Various options are available. Morse tutor with Complete Source Code and Binary is available for Download (32KB).

HAMIC - The Ham Intelligent Calculator - HAMIC, is a program designed to simplify a number of calculations commonly used by HAMs. It is designed for the HAM radio hobbyist, but may be useful to others as well. HAMIC has a simple to use, but powerful graphical interface that allows solving simple circuits such as resistors in series or parallel, or more complex circuits such as L networks or T networks. As well, other calculations such as SWR and reactance conversions are supported. Windows shareware.

Defpom's CB Radio Simulator - It is a application which can be used for troubleshooting CB radio faults, by giving a graphical display of the normal operating frequencies generated by various parts of the CB radios circuits, it can help you identify if a frequency is incorrect or even missing. Another good use for this software is simulating possible frequency expansions, as it allows you to choose any frequency that the PLL is capable of generating, so you can see what the radio will allow you to get !

DXCluster for iPhone - DXCluster let you know in real time who is on the frequencies and where it was listened the last time. It let you create filters to only see which frequency/CQ Zone/ITU Zone and/or Country and after that you can have an alarm corresponding to a specific Zone or a specific country that raise a popup

Audio Preamp - Easy circuit that provide good gain to weak audio signals

KB2LJJ Radio Mods Database  ^pop - The KB2LJJ radio mods database offers approximately 12,000 Radio Mod's, circuits and manuals.

DigChip IC database - DigChip is a provider of integrated circuits documentation search engine, it's also distributor agent between buyers and distributors excess inventory stock.

Electronic symbols - Analog digital symbols, identification of components, units and conversi¥n tables for electronics circuits design

50MHz frequency counter, V-meter - Circuit schematic PCB and photo documentation on building a 50 Mhz frequency counter

7 MHz SSB Transceiver  ^pop - Circuit diagram and discription of 7 MHz Ham Radio SSB Transceiver. Transceiver using two MC1496, 4.43 MHz Ladder filter, LM386, LM324 and IRF840 in final.

Ham Radio Circuits  ^pop - Circuits of SSB Transceiver, AM DSB Transmitter, Antennas, BFO, VFO, 807, FM Mike, Crystal filter and more.

HSCW transmit interface box - Versatile transmit interface circuit

ACWS: Automatic CW Sender by iz7ath - Simple circuit, with a simple push, transmit a memorized Cw messages

Homebrew resources for wireless enthusiasts - PDF resources containing information on low cost ssb,am,cw circuits, which are useful for beginners.

Regenerative Radio Receiver Circuit - Useful and well thought out regenerative receiver design

WD5HOH Regenerative(Regen) Receiver - This web page describes a small, single tuned circuit regenerative receiver primarily for daylight reception in the 16, 19, 22 and 25 meter international shortwave broadcast bands.

Interface for MS_DSP - Minimal interface circuits for receiver and transmitter audio, also for PSK31

Build A Vector Network Analyzer - The VNA (vector network analyzer) is an essential tool for measuring the complex impedance of a circuit at a given frequency. Article on how to build a Impedance analyzer.