GPS And SDR Combine Forces

Software-defined radio (or SDR) is a relatively new (to average tinkerers, at least) way of sending and receiving radio signals. The interest in SDR exploded recently with the realization that cheap USB TV tuner cards could be used to start exploring the frequency spectrum at an extremely reduced cost. One of the reasons that this is so advantageous is because of all of the options that a general-purpose computer opens up that go beyond transmitting and receiving, as [Chris] shows with his project that ties SDR together with GPS.

The goal of the project was to automatically tune a radio to the local police department’s frequency, regardless of location. To do this, a GPS receiver on a computer reports information about the current location. A JavaScript program feeds the location data to the SDR, which automatically tunes to the local emergency services frequencies. Of course, this relies on good data for what those frequencies are, but this is public information in most cases (at least in the US).

There are a lot of opportunities here for anyone with SDR. Maybe an emergency alert system that can tune to weather broadcasts if there’s a weather alert, or any of a number of other captivating projects. As for this project, [Chris] plans to use Google’s voice recognition software to transcribe the broadcasts as well. The world of SDR is at your fingertips to do anything you can imagine! And, if you’re looking to get started in it, be sure to check out the original post covering those USB TV tuner dongles.

Ham Radio Public Service Activities – Rewarding and Useful

“Hi! I’m Rud, Kilo Five Romeo Uniform Delta.” That’s me introducing myself at a ham meeting. Ham radio operators kid that we don’t have last names, we have call signs.

Becoming an Amateur Radio Operator (ARO), our more formal name, is not difficult and opens a world of interesting activities, including hacking. As with anything new, becoming actively involved with an existing club can be daunting. The other hams at a meeting are catching up with their buddies and often seem uninterested in the new guy standing nearby. Some groups will invite new members to stand and introduce themselves early in the meeting, which helps break the ice.

Regardless of how anyone else acts at the meeting there is one ham who is always looking for someone new – the ham who manages public service events, where amateur radio operators help establish communications for large public gatherings. These can be local bike rides, walks, or runs; I’ve even seen hams working an art show. In the nomenclature adopted since 9/11, these are “planned incidents” in contrast to “unplanned incidents” like hurricanes, tornadoes, forest fires, snow storms, and other natural or man made disasters. Working planned incidents is training for unplanned incidents when that need arises. The basic activities for AROs are the same.

Here in the Houston there are two very big events that enlist hundreds of hams. The big one in January is the Houston Marathon. The other large event is the Houston to Austin Multiple Sclerosis 150 (MS 150) mile bike ride in April. That event starts on Saturday morning, takes a break mid-way on Saturday evening, and finally wraps up late on Sunday evening. Starting in the fall there are warm-up events for the Marathon and in the late winter bike rides to prepare riders for the MS-150. There are also other marathons, Iron Man races, walks, runs, and races throughout the year. Wherever your are, there are probably events nearby and they can always make use of your radio capability.

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Parts bin Emergency Lights Deal with Tornado’s Aftermath

Sometimes having a deep inventory of parts in your shop is a pain – the clutter, the dust, the things you can’t rationally justify keeping but still can’t bear to part with. But sometimes the parts bin delivers and lets you cobble together some emergency lighting when a tornado knocks out your power.

It has been hard to avoid discussions of the weird weather in the US this winter. The eastern half of the country has had record warm temperatures, the west has been lashed by storms, and now December tornadoes have ripped through Texas and other parts of the south, with terrible loss of life and wide-ranging property damage. [TheTimmy] was close enough to one massive EF4 tornado to lose power on Saturday night, and after the charm of a candlelight Christmas evening wore off, he headed to the shop. He had a bunch of sealed lead acid batteries from old UPSs and a tangle of 12V LED modules, and with the help of some elastic bands and jumper clips he wired up a bunch of lights for around the house. Safer than candles by a long shot, and more omnidirectional than flashlights to boot.

The power came back before the batteries ran out of juice, so we don’t get to see any hacks for recharging batteries in a grid-down scenario. Still, it’s good to see how a deep parts bin and good mindset can make a positive impact on an uncomfortable situation. We’ve seen similar hacks before, like this hacked cordless tool battery pack or powering a TV with 18650 batteries. Be sure to share your story of epic power-outage hacks in the comments below.

Emergency Power Based on Cordless Drill Batteries

[Don Eduardo] took matters into his own hands after experiencing a days-long power outage at his house. And like most of us have done at least one, he managed to burn his fingers on a regulator in the process. That’s because he prototyped a way to use power tool batteries as an emergency source — basing his circuit on a 7812 linear regulator which got piping hot in no time flat.

His next autodidactic undertaking carried him into the realm of switch-mode buck converters (learn a bit about these if unfamiliar). The device steps down the ~18V output to 12V regulated for devices meant for automotive or marine. We really like see the different solutions he came up with for interfacing with the batteries which have a U-shaped prong with contacts on opposite sides.

The final iteration, which is pictured above, builds a house of cards on top of the buck converter. After regulating down to 12V he feeds the output into a “cigarette-lighter” style inverter to boost back to 110V AC. The hardware is housed inside of a scrapped charger for the batteries, with the appropriate 3-prong socket hanging out the back. We think it’s a nice touch to include LED feedback for the battery level.

We would like to hear your thoughts on this technique. Is there a better way that’s as easy and adaptive (you don’t have to alter the devices you’re powering) as this one?

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DIY Phone Charger Born From Cyclone Disaster

As convenient as cell phones are, sometimes these power-hungry devices let us down right at the worst time. We’re talking about battery life and how short it is in modern cell phones. Sure that’s totally inconvenient sometimes but it could be way worse. For example: during a natural disaster. A cyclone hit [Ganesh’s] home city and the entire area had lost power for 10 days. He couldn’t plug in his phone to charge it even if he wanted to. After realizing how dependent we are on the electrical grid, he did something about and built a phone charger out of parts he had kicking around.

The charger is quite simple. The user cranks on a DC motor and the output power goes into a LM2596-based step-down voltage regulator. The output of the regulator is then connected to a female USB connector so that any USB cord can be plugged in. As long as the motor is cranked fast enough to put out at least 8vdc, a steady stream of 5v will be available at the USB connector. Max current output of the system has been measured at 550mA.

[Ganesh] admits this isn’t a practical every-day charger but in a pinch it will certainly do the trick. It is even possible to build a makeshift charger out of a cordless drill.

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Human powered emergency cell phone charger

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Power outage? For the average citizen it’s very easy to take electricity for granted. Go a few hours or more without it though, and you’ll suddenly be reminded just what a luxury it is. During an emergency situation, sometimes you have to come up with alternative methods to get the job done. This human powered cell phone charger is a great example.

Using just a few ordinary around the house items, [The King of Random] turned a cordless electric drill into a human powered electrical generator. If the drill is run in reverse and cranked by hand, the generated energy can be transferred through the battery terminals to a connected device.  So, he cut a USB charger cable in half and wired it up to the terminals to be able to charge his cell phone. Some yarn, a salad fork, a mixing beater, a scrap 2″x4″, some aluminum foil, and scotch tape were the only other materials he used. Using this technique, a totally dead phone battery was charged in around 3 hours.

Remember that this method is only intended to be used in an emergency, not as every day practice. Using these methods could potentially overheat or damage your gear, so be careful.

Check out the MacGyver worthy video tutorial after the break.

[via Neatorama]

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