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This project goes through the process of designing and building a simple RF transmitter and RF receiver pair that operate at 27 MHz. Only basic parts like 555 timers and 2N2222 transistors are used to make the modules, so it’s generic but fun.
Simple Pyro RF Transmitter – Receiver (27 MHz) - [Transmitter - Receiver]
PureVLC brings its first Visible Light Communication (VLC) product to the market. VLC transmits data wirelessly using visible light as its medium instead of radio waves. VLC was demonstrated over a year ago when Harold Haas, professor of Mobile Communications at the University of Edinburgh, successfully demonstrated the technology at a TED conference. He streamed a HD video to a screen using a LED light bulb as transmitter.
Using the visible light spectrum to transfer data wirelessly will ease the burden on the overcrowded radio frequencies. The visible light spectrum is 10,000 larger than that of radio. VLC can potentially realize ultra-high-speed transfer rates and high data density. [via]
LEDs Just Got Brighter, They Now Talk Too - [Link]
Scott @ swharden.com writes:
Last week I spoke with a student in the UF aerospace engineering department who told me he was working with a group of high school students to add a payload to a high-altitude balloon being launched at (and tracked by) NASA. We tossed around a few ideas about what to put on it, and we decided it was worth a try to add a transmitter. I’ll slowly add to this post as the project unfolds, but with only 2 days to prepare (wow!) I picked a simplistic design which should be extremely easy to understand by everyone.
High Altitude Balloon Transmitter - [Link]
This small transmitter can reach more than 1 km under good conditions . The input can either be an electret microphone or other audio source. The frequency is given by CV (trimmer common 2-20 or 3-30pF) and L1 4 or 5 turns of 22 AWG enameled wire with a diameter of 1 cm with air core.
FM transmitter with 2N2218 - [Link]
Here’s an app note about a circuit for detecting and locating radio frequency transmitters. The circuit is based around the MAX2015 RF detector which outputs a voltage proportional to the strength of a received RF signal in the 100 MHz to 3 GHz range – [via]
This design idea showcases a circuit that detects RF “bugs,” such as hidden wireless cameras, eavesdropping microphones, and other spying devices that emit RF frequencies in the 100MHz to 3000MHz range. A modification to this circuit not only detects RF bugs, but also locates their hidden positions.
App note: Detecting and locating RF bugs - [Link]
electronics-diy.com writes:
With this Stereo FM Transmitter with BA1404 you will be able to create a mini stereo FM station and broadcast to your entire home, a simple way to have an audio link wireless with ease. With the FM transmitter BA1404 Hifi Stereo you can stream your music from your iPod MP3, satellite receiver, computer, DVD player, Mobile Phone, MP4 player and MP3 and other audio source directly to an FM receiver with crystal clear sound.
Stereo FM transmitter - [Link]
This page describes hardware and software design for digital USB FM transmitter, called FmStick. This hardware does not contain analogue parts (except RF part). The main idea – is to create transmitter, that looks like usb flash stick. This idea is not new, You can see some of this designs in market, like Griffi RocketFM or Keene USB FM Transmitter, both avaliable on Amazon. But device, described below – is different. It does not have analogue sound parts at all, and it supports RDS, and it is powerful.
The main features of this device are:
- Transmit Frequency: 76 … 108 Mhz
- Transmit Power: -60 … 20 dBm[1]
- Audio Compression: Yes
- Audio Limitation: Yes
- Audio Signal Measurements: Yes
- Pre-Emphasis: 0/50/75 uS
- RDS: Yes
- RDS RadioText: Yes
- RDS Time: Yes
- Drivers Installation Needed: No[2]
- Software Needed: No[3]
- LEDs That shows state: Yes
- External power needed: No
FmStick Digital USB FM Transmitter - [Link]
Ian Johnston wasn’t content to use the usual RC control joystick for his RC flying. He decided to reinvent the controller using a couple of old PC joysticks, an Arduino and the Tx PCB from Thomas Scherrer’s LRS kit.
You can read the details on this project on Ian Johnston’s website. He also has the entire project and code available in PDF form. [via]
RC joystick transmitter using Arduino - [Link]
Sean Michael Ragan writes:
This circuit is commonly credited to Japanese multimedia artist Tetsuo Kogawa. It takes audio input through a 1/4″ phono jack and, constructed as shown, without the optional antenna connections, will broadcast an FM radio signal about 30 feet.
Micro FM Transmitter – [Link]
tonieletronica.50webs.com writes:
Circuit of stereo FM transmitter of of high quality using integrated circuit ba1404 for mp3, mp4, ipod, computer, radio of the car. Transmit of your equipment of portable audio for the radio of your car, transmitters of fm of low potency are the ideal for transmission wireless of audio sign for fm receivers. Mainly in that case that is treated of transmitter of FM stereo with ba1404. The heart of that circuit is the circuit integrated ba1404, that is a mini fm transmitter, that already counts with the necessary internal circuits for transmission in fm. just being necessary to increase some components discman or any other audio source turning the wireless. If you already set up other transmitters of transistorized fm it will see that when setting up that with having integrated BA1404, that the quality of the sound and the frequency stability is excellent. Besides the but it presents easy assembly.
Stereo FM Transmitter with BA1404 – [Link]
