junk box

5 Articles

The Complex Issue Of Hackspace Donations

April 14, 2017 by 74 Comments

More than one member of the Hackaday team has significant involvement in a hackspace, as member, director, or even founder. We talk about hackspaces quite rarely on these pages though, not because we don’t have anything to say on the matter but because even when we write in general terms our fellow members invariably think it’s all about them rather than the hackspace world at large.

For once I’m going to break the silence, and not only talk about hackspaces, but talk about my own hackspace in specific terms. Because, fellow Oxford Hackspace members, this isn’t about you personally though I’m using our home to illustrate a point. The topic is a thorny issue that must affect all spaces, that of donations of physical items. People want to help their hackspace, they have a pile of what they consider to be good stuff, and when they’re having a clear-out they make a donation. But, as we all know, “one man’s trash is another man’s treasure” and vice-versa. Continue reading “The Complex Issue Of Hackspace Donations” →

Partsbox.io Wants To Organize Your Junk Box

November 18, 2016 by 45 Comments

There are many ways to divide the hacker community into groups. Tubes vs transistors. Emacs vs VI, microcontroller vs discrete component designers. However, one of the more fundamental divisions in the community is how you organize your parts. We’ve seen giant warehouses with carefully organized bins and cabinets full of components, and we’ve seen storage crates with tangles of wires and bits of electron-bending components scattered among the wires.

dbIf you are in the former camp, you’d probably enjoy partsbox.io (see image, right). If you are in the latter group, you probably need to check it out even more than the other people. The idea is simple: an online place to keep an inventory of your electronic parts. The implementation is not as simple, though. The web application will work on a mobile device or just about anywhere. You can view your components by type, by location (the shoe box under the bed vs the parts bin in the closet), or by a project’s bill of materials. You can use “known” parts or create private parts for things no one else has (for example, your custom PC boards, or those 3D printed brackets you made to hold a microswitch). If you add data for a component you can make it available to other users.

Continue reading “Partsbox.io Wants To Organize Your Junk Box” →

Too Good To Throw Away: Dealing With An Out-Of-Control Junk Hoard

October 13, 2016 by 193 Comments

There it was, after twenty minutes of turning the place over, looking through assorted storage boxes. A Thinwire Ethernet network. About the smallest possible Thinwire Ethernet network as it happens, a crimped BNC lead about 100mm long and capped at each end by a T-piece and a 50 ohm terminator. I’d been looking for a BNC T-piece on which to hook up another terminator to a piece of test equipment, and I’d found two of them.

As I hooked up the test I wanted to run I found myself considering the absurdity of the situation. I last worked somewhere with a Thinwire network in the mid 1990s, and fortunately I am likely to never see another one in my life. If you’ve never encountered Thinwire, be thankful. A single piece of co-ax connecting all computers on the network, on which the tiniest fault causes all to fail.

So why had I held on to all the parts to make one, albeit the smallest possible variant? Some kind of memento, to remind me of the Good Old Days of running round an office with a cable tester perhaps? Or was I just returning to my past as a hoarder, like a Tolkienic dragon perched atop a mountain of electronic junk, and not the good kind of junk?

Continue reading “Too Good To Throw Away: Dealing With An Out-Of-Control Junk Hoard” →

Dusty Junk-bin Downconverter Receives FM On An AM Radio

October 6, 2014 by 10 Comments

This amateur radio hack is not for the faint of heart! With only three transistors (and a drawer-full of passive parts), [Peter Parker, vk3ye] is able to use a broken-looking AM car radio to receive FM radio signals (YouTube link) on 2 meters, an entirely different band.

There are two things going on here. First, a home-made frequency downconverter shifts the 147 MHz signal down to the 1 MHz neighborhood where the AM radio can deal with it. Then, the AM radio is tuned just slightly off the right frequency and the FM signal is slope detected.

The downconverter consists of a local tuned oscillator and a mixer. The local oscillator generates an approximate 146 MHz signal from an 18 MHz crystal, accounting for two of the three transistors. Then this 146 MHz signal and the approximately 147 MHz signal that he wants to listen to are multiplied together (mixed) using the third transistor.

If you’re not up on your radio theory, a frequency mixer takes in two signals at different frequencies and produces an output signal that has various sums and differences of the two input signals in it. It’s this 147 MHz – 146 MHz = 1 MHz FM signal, right in the middle of the AM radio band’s frequency range, that’s passed on to the AM radio.

Next, the AM radio slope detects the frequency-modulated (FM) signal as if it were amplitude modulated (AM). This works as follows: FM radio encodes audio as changes in frequency, while AM radios encode the audio signal in the amplitude, or volume, of the radio signal. Instead of tracking the changing frequency as an FM radio would, slope detectors stick on a single frequency that’s tuned just slightly off from the FM carrier frequency. As the FM signal gets closer to or farther away from this fixed frequency, the received signal gets louder or quieter, and FM is detected as AM.

At 5:23, [vk3ye] steps through the circuit diagram. As he mentions, these are old tricks from circa 50 years ago, but it’s very nice to see a junk-box hack working so well with so few parts and receiving (very) high frequency FM on an old AM car radio. A circuit like this could make a versatile front end for an SDR setup. It makes us want to warm up the soldering iron.

Continue reading “Dusty Junk-bin Downconverter Receives FM On An AM Radio” →

T.G.I.M.B.O.E.J. Turns One

July 2, 2009 by 14 Comments

tgimboej

The Great Internet Migratory Box of Electronics Junk, or T.G.I.M.B.O.E.J. has turned one. In the last year, they’ve learned a lot of things. They learned that lots of people are willing to contribute. Hundreds have signed up on the site to participate. Theyve also learned that laziness is the key road block on this project. The boxes that have stalled generally sitcollecting dust, simply because someone hasn’t bothered to ship it off. If you’re curious what kinds of stuff ends up in one of these, check our initial post. There aren’t any guarantees though, it all depends on what people toss in.