Repairs You Can Print: Fixing A Chewed Up Remote

February 1, 2018 by Dan Maloney 17 Comments

What is it about remote controls? They’re like some vortex of household chaos, burrowing into couch cushions while accusations fly about who used it last. Or they land in just the right spot on the floor to be stepped on during a trip to the bathroom. And don’t get us started about the fragility of their battery case covers; it’s a rare remote in a house with kids whose batteries aren’t held in by strips of packing tape.

But [Alex Rich]’s Bose radio remote discovered another failure mode: imitating a dog chew toy. Rather than fork out $90 for a replacement, [Alex] undertook a 3D-printed case to repair the chewed remote. He put an impressive amount of reverse engineering into the replacement case, probably expending much more than $90 worth of effort. But it’s the principle of the thing, plus he wanted to support some special modifications to the stock remote. One was a hardware power switch to disconnect the batteries entirely, hidden in the bottom shell of the case. The second was the addition of a link to his thermostat to adjust the volume automatically when the AC comes on. That required a Trinket inside the remote and a few mods to make room for it.

Yes, this project dates from a few years back, but [Alex] only just brought it to our attention for the Repairs You Can Print contest. Got some special unobtanium part that you were able to print to get out of a jam? Enter and win prizes to add to the glory of fixing something yourself.

ESP32 Makes For World’s Worst Radio Station

January 28, 2018 by Dan Maloney 14 Comments

We can say one thing for [bitluni]: the BOMs for his projects, like this ESP32 AM radio transmitter, are always on the low side. That’s because he leverages software to do jobs traditionally accomplished with hardware, always with instructive results.

In this case, the job at hand is creating an RF oscillator in the broadcast AM band and modulating some audio onto it. From his previous experience using an ESP32 to watch video on an oscilloscope, [bitluni] knew that the microcontroller’s DACs were up to the task of producing an 800-kHz signal, and he managed to produce a more-or-less sine wave carrier with some clever code. His sketch takes data from a header file, modulates it onto the carrier, and sends it out over the ether using a short stub of wire for an antenna. The range is severely limited, but for what it is, it gets the job done and shows the basics. And as a bonus, [bitluni] included a bit of JavaScript that turns an audio file into a header file that’s ready to go out over the airwaves for all your trolling needs.

If you’re looking for a little more range for your low power transmitter and you’re a licensed amateur operator, you might want to explore the world of QRP radio.

Continue reading “ESP32 Makes For World’s Worst Radio Station” →

Drink Lots Of Beer To Raise Your Monopole

January 26, 2018 by Jenny List 19 Comments

When we published a piece about an ADS-B antenna using a Coke can as a groundplane, Hackaday reader [2ftg] got in contact with us about something with a bit more… stature.

A monopole groundplane antenna is a single vertical conductor mounted on an insulator and rising up above a conductive groundplane. In radio terms the groundplane is supposed to look as something of a mirror, to provide a reflection of what would come from the other half of a dipole were there to be two conductors. You can use anything conductive as your monopole, a piece of wire, (in radio amateur humour) a piece of wet string, or even beer cans. “Beer cans?” you ask incredulously, expecting this to be another joke. Yes, beer cans, and [2ftg] has been good enough to supply us with a few examples. The first is a 57-foot stack of them welded together in the 1950s for use on the 80 metre band ( we suspect steel cans may have been more common than aluminum back then), the second is a more modest erection for the 2 metre band, and the final one consists of photographs only of an HF version that looks a little wavy and whose cans are a little less beery.

The reporting in the 1950s piece is rather cheesy, but does give a reasonable description of it requiring welding rods as reinforcement. It also gives evidence of the antenna’s effectiveness, showing that it could work the world. Hardly surprising, given that a decent monopole is a decent monopole no matter how many pints of ale you have dispatched in its making.

The Coke can ADSB can be seen in all its glory here, and if all this amateur radio business sounds interesting, here’s an introduction.

Beer cans picture: Visitor7 [CC BY-SA 3.0].

Dust Off Those AM Radios, There’s Something Good On!

January 12, 2018 by Gregory L. Charvat 53 Comments

If you are into vintage electronics or restoring antique radio equipment you may be very disappointed with the content offerings on AM broadcast radio these days. Fortunately there is a way to get around this: build your own short-range AM broadcast station and transmit curated content to your radios (and possibly your neighbors). There are several options for creating your own short-range AM broadcast station, and this gives you something fun to tune into with your vintage radio gear.

Continue reading “Dust Off Those AM Radios, There’s Something Good On!” →

Amazon Echo Dot Upgraded To Retro Futuristic Look

December 29, 2017 by Bob Baddeley 18 Comments

It takes a surprising amount of planning and work if you want something to look old. [vemeT5ak] wanted the Echo Dot sitting on his desk to fit a different aesthetic motivated by a 1940s Canadian radio. Armed with Solidworks, a Tormach CNC, and some woodworking tools at Sector67 hackerspace, he built a retro-futuristic case for the Amazon Alexa-enabled gadget. Future and past meet thanks to the design and material appearance of the metal grille and base molding wrapping the wood radio case. The finishing touch is of course the ring of blue light which still shines through from the Echo itself.

A short USB extension cable connects the Echo Dot to the back of the enclosure, and the cavernous inside plus ample holes provide a nice rich sound.

It took about 15 hours of modeling, scaling, and tweaking in Solidworks with an interesting design specification in mind: single-bit operation. This single-bit is not in the electrical sense, but refers to the CNC milling operation. All pieces are cut with a 1/4″ end mill, without any tool changes. Metal pieces were milled from 6061 aluminum and the hickory case (with burgundy stain) was mostly cut on a table saw, but the holes were CNC machined.

What looks like an otherwise perfect build has a single flaw that eats up [vemeT5ak]’s soul; the Echo Dot has a draft angle that wasn’t considered during modeling, and the hole is ever so slightly too wide, meaning it didn’t press fit perfectly flush. Fortunately it’s not noticeable behind the metal grill, and unless you knew (please help keep his dirty little secret), you would think everything turned out perfectly.

It turns out building a case for the Echo Dot is challenging for a few reasons; the rubbery material on the bottom doesn’t allow anything to stick to it, and the sides are smooth and featureless with a taper that makes it difficult to lock it in. Many cases resort to clipping over the top to hold it in place. Others install it into a fish or a furby.

Radio Amateuring Like It’s 1975

December 7, 2017 by Jenny List 33 Comments

It was a tweet from an online friend in the world of amateur radio, featuring a transmitter design published in Sprat, the journal of the G-QRP club for British enthusiasts of low-power radio. The transmitter was very simple, but seriously flawed: keying the power supply line would cause it to exhibit key clicks and frequency instability. It would probably have been far better leaving the oscillator connected full-time and keying the supply to the amplifier, with of course a suitable key click filter.

[M0CVO]'s Tweet that started it all — [M0CVO]’s Tweet that started it all

We’ve all probably made projects that get the job done at the expense of a bit of performance and economy, and from one angle this circuit is a fantastic example of that art. But it’s not the shortcomings of direct PSU keying a small transmitter that has brought it here, but observation instead of what it represents. Perhaps my social group of radio amateurs differs from the masses, but among them the universal lament is that there is nothing new in a simple transistor transmitter that could just as well have been published in 1977 as 2017.

To explain why this represents a problem, it’s worth giving some background. Any radio amateur will tell you that amateur radio is a wonderful and diverse pastime, in fact a multitude of pastimes rolled into one. Working DX? Got you covered. Contesting? UR 599 OM QRZ? Digital modes pushing the envelope of atmospheric propagation? Satellites? SDRs? GHz radio engineering? All these and many more can be yours for a modest fee and an examination pass. There was a time when radio was electronics, to all intents and purposes, and radio amateurs were at the vanguard of technology. And though electronics has moved on from those days of purely analogue communications and now stretches far beyond anything you’d need a licence and a callsign to investigate for yourself, there are still plenty of places in which an amateur can place themselves at the cutting edge. Software defined radio, for instance, or digital data transmission modes. With an inexpensive single board computer and a few components it is now possible to create a software-defined digital radio station with an extremely low power output, that can be copied on the other side of the world. That’s progress, it’s not so long ago that you would have required a lot of dollars and a lot of watts to do that. Continue reading “Radio Amateuring Like It’s 1975” →

Grabbing Better Images From A Newer Russian Satellite

December 5, 2017 by Will Sweatman 46 Comments

The Soviet Union took the world by surprise when it sent its Sputnik satellite into low earth orbit way back in 1957. The event triggered a space race between the Soviets and the United States and ushered in technologies that would go on to touch the lives of every human on earth. Today, several nations have a space program. And one of the more useful things to put in orbit are weather satellites.

In 2014, the Russians launched their Meteor N M-2 weather satellite into a polar orbit. The part that were most interested in is the fact that it transmits images at 137.1 MHz using the standard LRPT protocol. However, the newer Meteor N M-2 transmits images at twelve times the resolution of US NOAA satellites. No typo there – that’s twelve (12!) times. Have we got your attention now?

We shouldn’t have to tell you to jump on over to [phasenoise’s] blog which gives you everything you need to start grabbing some of these awesome images.

Now, before you get your jumper wires in a bunch – we are well aware that receiving satellite images is nothing new.

Thanks to [Roy Tremblay] for the tip!