HamRadioTweets Gets The Word Out

December 23, 2014 by Rick Osgood 24 Comments

In times of crisis, or extreme government control, it can be difficult to spread critical information to people who can help. A good example of this was during the Arab Spring in 2011. When your Internet connection is taken away, it can feel as though all is lost. Unless you have a ham radio, that is.

For many people the thought of ham radio conjures up images of old guys twisting knobs listening to static, but it’s actually come a long way in our modern digital age. For example, you can now send tweets via ham radio. This project was actually started in 2011 by [Bruce Sutherland]. The Egyptian government had shut down the country’s Internet access after citizens were posting information about the extreme violence they were facing. [Bruce] wanted a way to help others get the word out, and he came up with HamRadioTweets. This system allows a user to send tweets via ham radio.

The system actually piggybacks off of a ham radio service called APRS. This service is most often associated with GPS tracking systems, such as those found in nearspace balloons, but it can also be used to send simple text messages over the air. APRS works thanks to the vast network of receiving stations setup all around the world. These stations can receive messages and then re-transmit them, greatly extending the reach of the original transmitter. Some of them are even hooked up to the Internet to get the messages to go distances that would be extremely difficult and unreliable by traditional means.

[Bruce’s] system hooked into the Internet component and watched for messages being sent specifically to “TWITR”. The Python based system would then read these messages and re-transmit them over Twitter. The project died out a while back after Twitter updated their API. Now, it’s been rebuilt on Ruby by [Harold Giddings]. The project website was handed over to [Harold] and he is currently maintaining it. Hopefully you’ll never need to use this software, but if the time comes you will be glad it’s available. You can watch [Harold] bounce an APRS message off of the International Space Station and on to Twitter in the video below. Continue reading “HamRadioTweets Gets The Word Out” →

Amateur Radio Transmits 1000 Miles On Voice Power

November 26, 2013 by Adam Fabio 50 Comments

Many of us tried the old “Two tin cans connected by a string” experiment as kids. [Michael Rainey, AA1TJ] never quite forgot it. Back in 2009, he built “El Silbo”, a ham radio transmitter powered entirely by his voice. El Silbo is a Double Side Band (DSB) transmitter for 75 meters. While voice is used to excite the transmitter, it doesn’t actually transmit voice. El Silbo is a CW affair, so you should bone up on your Morse Code a bit before building one. Like many QRP transmitters El Silbo’s circuit is rather simple. A junk box loudspeaker is installed at the bottom of the can to convert voice power to electrical power. The signal is passed through a step up transformer, and used to excite a 75m crystal. Two NPN transistors (in this case MPS6521) pass the signal on through a second transformer. The signal is then routed through an LC network to the antenna.

Back in 2009, [Michael] brought El Silbo to the Maine coast in an attempt to make a transatlantic contact. This isn’t as far-fetched as it sounds – [Michael] has “crossed the pond” on less power. While the attempt wasn’t successful, [Michael] has made connections as far as 1486km, or 923 miles. That’s quite a distance for simply yelling into a tin can! One of [Michael’s] favorite El Silbo stories is a 109KM conversation (QSO) he had with W1PID. [Michael] found that the signal was so good, he didn’t have to yell at all. He reduced power by dropping to his normal speaking voice for the “dits and dahs”. The two were able to converse for 17 minutes with [Michael] only using his speaking voice for power. We think this is an amazing achievement, and once more proof that you don’t need a multi-thousand dollar shack to make contacts as a ham.

Continue reading “Amateur Radio Transmits 1000 Miles On Voice Power” →

BITX, A Return To Hackers’ Paradise

November 13, 2013 by Adam Fabio 50 Comments

bitx

[Bill Meara] has finished up his radio. It both looks and sounds great. It was only a few weeks ago that [Bill] posted a guest rant here on Hackaday. The Radio he mentioned building in the rant is now complete. The transceiver itself is a BITX, a 14MHz Single Sideband (SSB) radio designed by Ashhar Farhan VU2ESE. Ashhar designed the BITX as a cheap to build, and easy to tune up transceiver for radio amateurs in India.

By utilizing parts easily sourced from scrapped TV sets, the BITX can be built for less than 300 Indian Rupee – or about $4.70 USD. In [Bill]’s own words, “Five bucks and some sweat equity gets you a device capable of worldwide communication.” He’s not kidding either. [Bill’s] first QSO was with a ham in the Azores Islands of Portugal.

[Bill] built his radio using the “Manhattan” building style, which we’ve seen before. Manhattan style uses rectangular pads glued down onto a copper ground plane. It makes for a more flexible design than regular old dead bug style building. Looking at all those components may be a bit daunting at first, but plenty of support is available. [Bill] has an 18 part build log on the soldersmoke website. There also is an active yahoo group dedicated to the BITX.

Non-destructive Breakdown Voltage Tester

June 23, 2008 by Will O'Brien 4 Comments

This applies more to older vacuum technology than your average solid state hardware, but [Richard] put together an interesting project. It’s designed to test a component for its breakdown voltage without destroying it. The general idea of the ‘BVT’ is to increase the voltage applied to a device until some current leakage is detected. Of course, any device that includes notes on probable arc length in relation to kilovolts is awesome by definition.