Working Software-defined Radio With A TV Tuner Card.

March 30, 2012 by Brian Benchoff 77 Comments

[Balint Seeber] just sent in a small yet timely project he’s been working on: a software radio source block for the Realtek RTL2832U. Now with a cheap USB TV tuner card, you can jump right into the world of software-defined radio.

[Balint]’s code comes just a week after hackaday and other outlets posted stories about using a $20 USB TV capture dongle for software defined radio. At the time, these capture cards could only write data directly to a file. With [Balint]’s work, anyone can use a cheap tv tuner dongle with HDSDR, Winrad, or GNU Radio. If you’ve ever thought about trying out software-defined radio, now might be the time.

Elsewhere on the Internet, a surprisingly active RTL-SDR subreddit popped up dedicated to using the Realtek RTL2832U tuner for software defined radio. There’s an awesome compatibility chart listing compatible USB dongles. The cheapest (so far, and subject to change) is the Unikoo UK001T available for $11 on eBay.

With his source block, [Balint] can listen to anything on the radio between 64-1700 MHz. The sample depth is 8 bits and the sample rate can be anything up to 3.2 MHz. You can watch [Balint] testing out his $20 GNU Radio rig after the break.

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Software Defined Radio From A USB TV Capture Card

March 20, 2012 by Brian Benchoff 48 Comments

With a simple digital TV USB capture card, you can build your own software defined radio or spectrum analyzer. While it may not be as cool as [Jeri Ellsworth]’s SDR, it’s still very useful and only requires $20 in hardware.

The only piece of hardware required for this build is a USB FM/DTV capture device with the Realtek RTL2832U chipset. So far, two USB sticks have been tested and the unit with the largest frequency range (64 – 1700 MHz) is available direct from China for $20.

Turning these cheap capture cards into software defined radios and spectrum analyzers was discovered by [Antti Palosaari] after sniffing the device. These cards demodulate the frequency and send all the data to the computer and is decoded via software. If you have one of these capture cards lying around, you can grab the software and load it up on your *nix box. Right now, the software only writes directly to a file, and may drop a few samples if writing to a hard disk instead of ram. Small problems, but we’re sure this project will pick up steam in the very near future.

via reddit

Old Radio + Old Phone = Android Media Station

March 8, 2012 by Mike Szczys 19 Comments

[Bjørn] combined some aging electronics he had around the house to create this Android media center. The enclosure is an FM-radio, but since he only listens to online media it wasn’t of much use to him. After sizing it up he realized it was a perfect candidate to receive his old HTC Hero Android phone.

The upper portion of the stock radio used to host controls for tuning the FM dial, adjusting volume, and switching the unit on and off. He cracked open the case, ditching the radio receiver and patching in to the amplifier. The volume knob was moved to the right side of the case, and a hole cut to receive the phone. Audio is pulled from the phone with the jack sticking out the left side. We’d love to see a future improvement using a right-angle jack (kind of like this charging hack) or patched directly into the phone’s circuit board. This way everything would fit inside the box.

Now he can listen to Internet radio, or stream some video like in the clip after the break.

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8-bit Computer Project Lands In A Philco Radio Case

March 5, 2012 by Mike Szczys 17 Comments

We’ve enjoyed seeing the development progress of Veronica, [Quinn Dunki’s] 8-bit computer project. It started out on a breadboard, then moved to edge-connected PCBs, and now [Quinn] has given Veronica a body of her own.

The donor is a Philco Model 42-327T and was produced in 1942. It was chosen because it is non-functional and missing several pieces. We wonder about the collector’s value of the piece but since [Quinn] snagged it from eBay there can’t be in huge demand right now. The teardown images are priceless. There seems to be no reasoning behind component placement for the beast. It looks more like a junk drawer packed full of relic components than something that actually worked once upon a time.

But we digress. After gutting the retro wooden case [Quinn] set out to fabricate her own face plate. Since she’s comfortable working with copper clad, she whipped up a negative design and etched the dashboard seen above. It mounts in the original dial opening, and hosts all of the controls she needs to work with the 8-bit computer. Just below is where the present buttons used to be located. You can just see the hexout display for reading data from the registers mounted in that void.

[Sprite_tm]’s Three-component FM Transmitter

January 26, 2012 by Brian Benchoff 54 Comments

When the Regency TR-1 transistor radio came out onto the market in the 1950s, it was hailed as a modern marvel of microelectronics. With only four transistors and a handful of other components, the TR-1 was a wonder of modern engineering. [Sprite_tm] may have those old-timers beat, though. He built an FM transmitter with the lowest parts count of any transmitter ever.

Like most of [Sprite_tm]’s builds, it’s an unimaginably clever piece of work. [Sprite] overclocked the internal RC oscillator of an ATtiny45 to 24 MHz. After realizing the PLL running at four times the frequency of the oscillator was right in the middle of the FM band, he set about designing a tiny FM transmitter.

[Sprite_tm] remembered his work on MONOTONE and made a short song for hit ATtiny. The firmware for the build takes the notes from his song and varies the 96 MHz PLL frequency a tiny bit, thereby serving as a tiny FM transmitter.

Does it work? Well, if you want to compare it to a Mister Microphone, the range is incredibly limited. That being said it works. It’s an FM transmitter built out of a microcontroller and a battery, and that’s very impressive. Check out [Sprite_tm]’s demo after the break.

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Hide Your Repeater And Gain A Radio

January 24, 2012 by Kevin Dady 41 Comments

[Bradley]’s workplace was recently put into a position where they needed to install a WIFI network to operate some wireless barcode scanners, which was left open for anyone to connect to. Management thought that the people in the shop, who didn’t really need internet, would get less work done if they had access to it. So they just simply stuck the access point as far away as they could. Problem with that theory is that the signal still reaches a little bit where they don’t want it, and people in the shop really want access, so a repeater is needed.

Of course this repeater cant be just sitting out in the open. so [Bradley] decided to hide the it inside of an old radio. Searching around he finally settled on a 10$ ebay radio from the 1980’s, which is large enough to hold the guts of a WRT54G. The routers AC adapter was popped open and wired into the AC input of the radio, the main board and antennas were epoxied to the back. Once everything is buttoned back up you’re left with a hidden repeater, and a fully functional radio.

Now hopefully none of his bosses read his blog!

Amazingly Realistic Skeleton Prop

November 1, 2011 by Mike Szczys 5 Comments

[Cjmekeel] spent weeks getting his Halloween display ready this year. The centerpiece of his offering is this full-sized motorized skeleton. But there’s a few other gems that he worked on to compliment it. There’s an old-fashioned radio whose dial moves mysteriously and plays a news flash warning of an escaped mental patient. He also spent a couple of dollars to outfit a crow with some glowing red eyes and a servo motor.

But the creepiness of the skeleton means you might not even notice those other props. He started with a rather boring looking plain plastic head and did some real magic to build up the rotting flesh and gaping wounds. Those penetrating eyes don’t hurt either. The head moves on a few servo motors which use random values and sleep periods for disturbingly jerky movements. Check out the video after the break to get a glimpse at what kept kids away from his house on Halloween.

This is just a build log and unfortunately there’s no post yet showing the finished product. If we can get enough information together we’ll try to run a follow-up.

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