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neelandan writes:
Probe for measuring in the Radio Frequency range built inside an earphone jack, designed to have minimum capacitance and complete shielding.
RF probe – [Link]
tehnikservice.net writes:
The following construction allows a simple cable tester to determine whether the cable network is present in high-frequency signal from the source. It is a contactless version of the tester to detect the presence of a signal at distances up to 2m. It can be used to control all types of signal cables, such as divorce Ethernet,modem connections, digital TV, etc. The circuit lights an LED at the moment it accepts RF energy around the cable.
Network Cable Tester – [Link]
Direct conversion RF receivers are different from the standard superheterodyne one as they don’t have IF stage, and so the radio signals are directly converted into audio signals. This project uses 3 555 timer ICs as the only active devices to construct a direct-conversion radio receiver for the 80 meter amateur radio band. [via]
555 Contest Entry: Direct conversion RF receiver for 80 meter amateur band - [Link]
Semtech has released a line of “power and go” inexpensive data transmitter chips. The new SX1240 and SX1242 ISM-band RF transmitters enable true data-in/RF-out capability, with only an external crystal and antenna impedance matching network needed. [via]
Semtech RF data transmitter chips – [Link]
If you are looking a wireless communication between two Arduino modules, this project might be helpful. It uses low costs RF transmitter and receiver from Sparkfun to establish a radio link between the Arduino boards up to 500 ft. Data can be transferred serially at the maximum rate of 2400 bps. [via]
Radio link between two Arduino boards – [Link]
electronics-diy.com writes:
Measurement of transmitter output RF power has never been easier and more precise. AD8307 USB 0-500MHz RF Power Meter allows to measure the power of transmitters from 1nW to 2W. Output is displayed in dBm, Watts (nW, uW, mW and W range) as well as input voltage. USB RF Power Meter is based on popular AD8307 watt meter IC and PIC18F2550 microcontroller. Instead of using LCD display module the meter connects to a PC via USB port and displays measurements on a computer via USB RF Power Meter software.
0-500MHz RF USB Power Meter using AD8307 – [Link]
William Dillon build this RF Transceiver using the MRF49XA from Microchip. He shares the design, code and board files on the link below so you can build your own. He also documents how to design the circuit that is based on an example on the datasheet and he includes calculations to made it working with the 434 MHz band and an AVR-based library for using his module.
RF Transceiver using the MRF49XA – [Link]
Raphael Cerqueira developed a simple protocol to use with cheap wireless transceivers. [via]
This is something i’ve been working on for a couple days and finally got something worth showing. After a while using Radio Frequency Links in some projects i realized that many messages are lost and it requires you to send them over and over again until it reaches the destiny and does what it is supposed to do. I then decided to do something about it and since i know i’m going to lose a few messages in the air at least send it again in a transparent way so it doesn’t bother me. In a few words this is an implementation of a protocol that guarantees that a message sent over a RF Link will get to its destiny no matter what. This implementation is based on RF Links, Arduino e Java. At the end of the explanation of the protocol there’s an example of where it can be usefull, so, let’s get it started.
Sending data reliably using cheap wireless chips - [Link]
NIST engineers are working with scientists from the University of Arizona (Tucson) and Boeing Research & Technology (Seattle, Wash.) to design antennas incorporating metamaterials — materials engineered with novel, often microscopic, structures to produce unusual properties. The new antennas radiate as much as 95 percent of an input radio signal and yet defy normal design parameters. Standard antennas need to be at least half the size of the signal wavelength to operate efficiently; at 300 MHz, for instance, an antenna would need to be half a meter long. The experimental antennas are as small as one-fiftieth of a wavelength and could shrink further. [via]
Remarkably small antennas - [Link]
Trax writes:
Here is my home-built, cloth iron soldered, range extender for CC1101 (included onboard) RF transceiver chip from Texas Instruments. You could say that it is a CC1101+CC2591, but for 868/920MHz band. I used MAX2233 RF amplifier from Maxim-IC. It can deliver up to +24dBm (250mW) of RF amplification with +10dBm of input.
250 mW RF modem – [Link]
