security alarm circuit

KGD - Reduced size antenna - A reduced size antenna made of two series resonant circuits with a radiant tube condenser in German

Camden County Amateur Radio Society - CCARS - Camden County Amateur Radio Society. Supporting the Department of Homeland Security's Emergency Communications Initiative while promoting Amateur Radio activity and fellowship in and around Camden County Georgia

Wulffert Technology LLC - Tower Light Monitor, Controller Alarm Systems for buildings, towers, antennas and airports

ATV 432 MHz transmitter - ATV 432 MHz AM transmitter schematic

FT-817 DC Circuit Protection - A schematic for a DX circuit protection for the Yaesu FT-817, provides protection from the external power supply overvoltage by DL2LTO in german

AFR Enterprises - AFR Enterprises a leading distributor of electronic components, semicondustors, diodes, Resistors, Integrated Circuits across the USA.

DX Cluster for Android Priority listing - DX Cluster is an DX Cluster client for Android smartphones DX Cluster supports: Real time DX spots, Different band and mode filters, A country filter for spotter or the spots, Prefix or call sign alarms

Transistor PA Biasing - Here is a simple circuit that can deliver the peak base current needed for linear ssb operation

Speech Intelligibility - Articles published by the Radio Society of Great Britain, basic principles, construction of a simple equaliser circuit

Recovering old NICAD and NMHI Cells - Old Nicads batteries and sometimes NMHI batteries usually end up with several cells being short circuit, as they suffer from crystal growth in the electrolyte

Semiconductors - Semiconductors, diodes and transistors, intregrated circuits

PCB with kitchen appliances - Cheap and relatively easy way of making professional quality printed circuit boards at home

Circuit Laws - Basic electronic circuit laws

A high perfomance Crowbar Circuit - The MC3423 can protect sensitive circuity from power supply transients or regulator failure when used with an external "Crowbar" SCR.

Low cost frequency counter - Low cost multifunctional seven digit LCD frequency counter, for your HAM radio shack

DRAKE TR7 Downloads - Circuit diagrams drake tr7, Schaltbilder Drake Tr7, antenna tuners, baluns, and home brew power supplies, dual tone ssb test generator, zweiton ssb test generator, zweiton testgenerator, dual tone test generator by DK4DDS

QLF Filter - Microprocessor based interface designed receives a signal from a Morse key, processes it, and re-transmits it to the radio. A microprocessor in the circuit is pre-programmed with a proprietary algorithm which makes a number of measurements and adjustments to the less percise human generated code.

Digital Wattmeter - 300nW to 30W - The digital wattmeter project was created for the purpose of measuring power in the range of 300nw to 30w.

144 MHz Antenna Pre-Ampilfier - Electronic circuit and components layout fot this VHF Preamp

Signal Source for AO40 mode S - Signal source circuit for 2.4 GHz by sv1bsx

TenTec Omni VI AGC modification - Modification leaves nearly all of the existing Omni agc circuitry intact, simply add an audio detector which modifies the delay characteristics of the original system by G3IXQ

DRM Demo Receiver - Christoph Petermann DF9CY DRM demonstration receiver project including Circuit Diagram and component list

Bartling RX-40 Receiver - Circuit Diagram and Construction of the Bartling RX-40 Joachim Münch DF4ZS

30 m Band Direct Conversion Receiver - The direct conversion receiver described consists of only a bandpass filter, mixer IC, VFO and audio filter. With only 22 parts, this simple circuit should take a few hours at the weekend to construct.

UHF on a VHF Rig - This circuit enables fair copy of strong 444 MHz signals, off a local repeater, using a 2m rig and a 1/4λ 70 cm indoor ground plane antenna.