A Universal RFID Key. RFID projects have been pretty prominent recently, ranging from projects here in Instructables, to our local Silicon Chip magazine in Australia publishing a RFID door lock project in their November issue.
Even I recently purchased a RFID door lock on eBay for $15 to lock my garage (so my front neighbor could get tools if he wanted to). We have known that the cheaper RFID technologies were pretty insecure for a number of years. Researchers have demonstrated cloners of all varieties, but simple RFID tags are still being used for access control. Even my current employer uses them. Build the BASIC SPY TRANSMITTER - Page 1 of 16. Build the 2 transistor Spy Transmitter Radio frequency projects can seem more difficult than most electronics projects because most of the time you cannot build them on a solderless breadboard and there may be parts used that are not easy to source such as coils and adjustable capacitors.
This project is focused towards those who have not yet attempted to build any kind of RF project, and it is laid out in such a way as to make it easy to explore the basic principles of RF circuitry and ensure a successful final product. This simple 2 transistor audio transmitter will send the sounds picked up in a room to any FM radio tuned to the same frequency as the transmitter, somewhere between 80 and 100 Megahertz. >>> High Altitude Balloon Transmitter « SWHarden.com. SUMMARY: A small group of high school students taking an AP class for college credit launched a high-altitude weather balloon with a small payload.
In addition to a video transmitter and GPS transmitter, they decided to include a simple transmitter built from scratch. This is the story of the project, with emphasis on the simple transmitter’s design, construction, implementation, and reception (which surprised me, being detected ~200 miles away and lasting the entire duration of the flight!) [sample.ogg]