Hobby Projects - Insulation tester, LED Circuits, Meters.
Showing posts with label Amateur-Radio-2. Show all posts
Showing posts with label Amateur-Radio-2. Show all posts

Monday, March 06, 2017

FM Remote Speaker System

A high quality, noise free, wireless FM transmitter/receiver may be made using the LM566 VCO and LM565 PLL Detector. The LM566 VCO is used to convert the program material into FM format, which is then transformer coupled to standard power lines. At the receiver end the material is detected from the power lines and demodulated by the LM565.

National Semiconductor Application Note 146 June 1975

The important difference between this carrier system and others is its excellent quality and freedom from noise. Whereas the ordinary wireless intercom uses an AM carrier and exhibits a poor signal-to-noise ratio (S/N), the system described here uses an FM carrier for inherent freedom from noise and a PLL detection system for additional noise rejection.

Carrier System Transmitter

Carrier System Transmitter
Two input terminals are provided so that both LEFT and RIGHT signals of a stereo set may be combined for mono transmission to a single remote speaker if desired. The input signal level is adjustable by R1 to prevent overmodulation of the carrier. Adding C2 across each input resistor R7 and R8 improves the frequency response to 20 kHz as shown inFigure 5. Although casual listening does not demand such performance, it could be desired in some circumstances.

Carrier System Receiver

Carrier System Receiver
The receiver amplifies, limits, and demodulates the received FM signal in the presence of line transient interference sometimes as high as several hundred volts peak. In addition, it provides audio mute in the absence of carrier and2.5W output to a speaker

Saturday, March 07, 2015

DL4YHF - Ham Radio and Homebrew

This page provides some tools (software by myself), hardware, and other information for radio amateurs, and some other not-radio-related stuff like the PIC programmer.

Frequency counter with a PIC and minimum hardware

This document describes the construction of small frequency counter with a cheap PIC microcontroller and a few seven-segment LED digits. The main features of the frequency counter are: frequency range 1 Hz ... 50 MHz (prototype worked up to 60 MHz but this exceeds the PIC's timing specifications)

Frequency counter with a PIC and minimum hardware

Frequency counter with a PIC and minimum hardware
by Wolfgang "Wolf" B├╝scher, DL4YHF - frequency range 1 Hz … 50 MHz

DL4YHF - Ham Radio and Homebrew

Thursday, November 18, 2010

Radio Electronics Projects - Hans Summers G0UPL

"I am not a professional electronics engineer, nor do I have an electronics degree. I make no claims for technical accuracy, good design, or necessarily even originality for the contents of these pages.

Low power QRSS beacon - Hans Summers G0UPL

Rather, I am a simple enthusiast attempting to convey my love and enjoyment of radio, electronics, laptops and computing and perhaps to inspire YOU to build something too."

Radio Electronics Projects - Hans Summers G0UPL

This ultra-low power QRSS beacon was designed to be as efficient as possible, and produce a milliwatt or few from low voltage, low current supply. My intention was to investigate the use of natural power sources to operate the beacon.

Steve G0XAR visited the G0UPL shack and took some photos of proceedings. Combined with a sneakily obtained photo of G0UPL sleeping somewhere in Texas en-route to Ozarkcon 2007, G0XAR produced this very nice QSL card suggestion!

Low power QRSS beacon - Hans Summers G0UPL

Sunday, November 29, 2009

N5ESE - Gizmos for QRP Ham Radio

"One day I noticed a project, obviously homebrew, mounted on a piece of plywood, and nearly covering the worktable. When I asked him what it was, he glowed as bright as the half-dozen tubes that lit up when he turned it on. Twenty seconds or so later, out spews from the speaker the cracklings and whistles of 40 Meter CW. I was amazed, and at that moment the homebrew bug bit me hard. I was determined to build something myself, and get my ham ticket."

N5ESE - Gizmos for QRP Ham Radio

N5ESE - Gizmos for QRP Ham Radio

N5ESE's GIZMOs For the QRP Homebrewer and Ham Operator

"Everybody loves a "gizmo". Hams have a weakness for them. Gizmos can be expensive for full-power amateur radio equipment, but homebrewing QRP gizmos is "cheap and easy". Most of the projects here cost less than $20 (or nothing, if you have a modest junk box), and take only a few hours to build). Most are even suitable for the novice builder. And all have real practical value, especially for homebrewers and QRP operators. "

Monday, August 24, 2009

The American QRP Club

The American QRP Club

The American QRP Club was formed in June 2003, and later incorporated, as a organization of ham radio operating enthusiasts interested in low power operation - these types of hams are called QRPers. The AmQRP Club is not affiliated with any geographic area and its membership does not meet monthly as do many regional radio clubs. Instead, the AmQRP provides online information, instruction, goods and services to the general QRP population for educational and enjoyment purposes.

AmQRP QRP Club Kits

Friday, June 19, 2009

Hendricks QRP Kits - QRPKits

Hendricks QRP Kits - QRPKits

Hendricks QRP Kits

Hendricks QRP Kits is a company that specializes in high quality, low cost QRP Kits.

Tuesday, May 12, 2009

ARRLWeb - Amateur Radio Operators

ARRLWeb - Amateur Radio Operators

ARRL is the national -USA membership association for Amateur Radio operators.

The seed for Amateur Radio was planted in the 1890s, when Guglielmo Marconi began his experiments in wireless telegraphy. Soon he was joined by dozens, then hundreds, of others who were enthusiastic about sending and receiving messages through the air--some with a commercial interest, but others solely out of a love for this new communications medium. The United States government began licensing Amateur Radio operators in 1912.

Tuesday, July 03, 2007

Ultimate Morse Code Web Site - PA3BWK

Ultimate Morse Code Web Site - PA3BWK

Wilko J. Hollemans PA3BWK Ultimate Morse Code Web Site - PA3BWK
  • pdf library
  • building projects
  • morse code study tips

Sunday, May 06, 2007

Homebrew Electronic Projects of Harry

Homebrew Electronic Projects of Harry

Harry's Homebrew Homepages; a resource for radio, hamradio and electronics in general.

Harry Lythall
SM0VPO/G4VVJ.

Antenna projects, Receiver circuits, Transmitters circuits, AF / Amps circuits, Morse Code, PSU circuits, Useful circuits, EPROM circuits, RF Converters, Synthesizer circuits.