Category Archives: Hacking

Raspberry Pi W Antenna Analysis Reveals Clever Design

The old maxim is that if you pay peanuts, you get a monkey. That’s no longer true, though: devices like the Raspberry Pi W have shown that a $10 device can be remarkably powerful if it is well designed. You might not appreciate how clever this design is sometimes, but this great analysis of the antenna of the Pi W by [Carl Turner, Senior RF Engineer at Laird Technology] might help remind you.

[Carl] used some fancy toys in his analysis, such as the awesome-looking antenna test chamber that his employer uses to test designs. He used this to measure two very interesting things; the radiation pattern of the antenna, and the efficiency. Simply put, the efficiency is a measure of how much of the energy you push into an antenna is emitted as RF radiation. There is always a little loss, but he found that the Pi W antenna has decent efficiency, with -3.5 dB losses at WiFi frequencies. That’s nowhere near as good as the stand-up antennas on your wireless router, but remember that the WiFi antenna on the Pi W is tiny compared to them: it is a small spot on the PCB made by removing several layers of copper, creating what engineers call a resonant chamber. That makes it a remarkable bit of engineering, keeping the cost down and using the copper layers that are already on the board to create the antenna rather than adding a new component.

The radiation pattern of the Pi W is also interesting. Because the antenna is located right on the PCB next to the HDMI and USB ports, you might expect that the signal would be much stronger in some directions than others. And you would be right: it seems that the metal shields of the two ports do block some of the radiated signals. However, it is worth remembering that WiFi signals also bounce around a lot, and other factors can influence how strong a connection is.

The final words of the analysis by [Carl] should be something that all hackers remember:

You can always learn things from clever designs and smart engineers. The amount of effort and creativity that has gone into this $10 computer is impressive—and the results speak for themselves.

 

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Browsing Modern Day BBS on the Epson PX-8 Laptop

As you read this, there are still people chatting away on Bulletin Board Systems all over the world. Running on newly written software and without the need to actually use a dial-up modem, these (slightly) more modern takes on the BBSs of yore can be compelling diversion for those who might want to decompress a bit from contemporary social networks.

[Blake Patterson] is one of these people, and he writes in to tell us about his recent experiments with using a particularly gorgeous example the Epson PX-8 “Geneva” laptop on modernized BBSs. The form factor of the device makes it a fairly convenient client for chatting, despite the somewhat unusual screen. Luckily, modern BBS software is able to cope with the PX-8’s 80 character by 8 line LCD display, it’s just a matter of getting the thing online.

The trick is tethering the PX-8 to a Linux machine as a serial terminal. [Blake] had to build a serial cable for the laptop, and then used a basic USB-to-serial converter to get it connected to a Raspberry Pi. Once you’ve logged in over serial, you can simply fire off a telnet command to connect to the BBS of your choice. In the video after the break, he demonstrates what it’s like browsing and chatting on a BBS using the PX-8. The screen certainly takes a bit of getting used to, but actually works fairly well given the nature of the BBS interface.

[Blake] recently gave us a look at a Wi-Fi “modem” for retro computers based on the ESP8266, if you’d rather cruise your favorite BBS without a dangling Pi.

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SDR IF Experiments

The R820T tuner IC is used in the popular Airspy software defined radio (SDR) as well as many of the inexpensive RTL SDR dongles. [TLeconte] did some experiments on intermediate frequency (IF) configuration of the chip, and you’ll find his results interesting.

Using 5 million samples per second and the device’s real mode, the tests look at a what comes out when the IC reads a noise source. There are two registers that set the IF parameters, but the tests show the effects these registers have in precise terms.

According to the post, there are three things you can set:

  • Coarse IF filter bandwidth : narrow/mid/large
  • Manual fine tuning IF filter bandwidth from 0 (large) to 15 (narrow)
  • High pass filter frequency from 0 (high) to 15 (low)

Some of the settings don’t make sense — at least at the 5 MHz sample rate — because of aliasing. However, it is instructive to see what each setting does. [TLeconte] uses Octave to visualize the data.

If you want to know more about SDR in general, we have something to get you started. If you want to do your own testing, consider using GNU Radio.

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Classic American Dial Phone Gets A GSM Makeover

For sturdy utilitarianism, there were few designs better than the Western Electric Model 500 desk phone. The 500 did one thing and did it well, and remained essentially unchanged from the mid-1940s until Touch Tone phones started appearing in the early 70s. That doesn’t mean it can’t have a place in the modern phone system, though, as long as you’re willing to convert it into a cellphone.

Luckily for [bicapitate], the Model 500 has plenty of room inside the case once the network interface is removed, because the new electronics take up a fair bit of space. There’s no build log per se, but the photo album makes it clear what’s going on. An Arduino reads the hook switch and dial pulses, while a Fona GSM module takes care of the cellular side of things. It looks like a small electret mic and a speaker replace the original transmitter and receiver. As a nice touch, the original ringer is used, but instead of trying to drive it electrically, [bicapitate] came up with a simple cam mechanism on a small motor. Driven at the right speed, the cam hooks the clapper arm, rings one bell, then releases it to let the clapper spring back to hit the other bell. Everything is powered by a LiPo, so it could be taken to the local coffee shop for some hipster hijinks.

We’ve seen similar retro-mods like this before using phones from all over the world; here’s a British take and one from Belgium, both using phones with equally classic lines.

[via r/arduino]

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The One-Transistor Flip-Flop

A flip-flop is one of the most basic digital electronic circuits. It can most easily be built from just two transistors, although they can and have been built out of vacuum tubes, NAND and NOR gates, and Minecraft redstone. Conventional wisdom says you can’t build a flip-flop with just one transistor, but here we are. [roelh] has built a flip-flop circuit using only one transistor and some bizarre logic that’s been slowly developing over on hackaday.io.

[roelh]’s single transistor flip-flop is heavily inspired by a few of the strange logic projects we’ve seen over the years. The weirdest, by far, is [Ted Yapo]’s Diode Clock, a digital clock made with diode-diode logic. This is the large-scale proof of concept for the unique family of logic circuits [Ted] came up with that only uses bog-standard diodes to construct arbitrary digital logic.

The single-transistor flip-flop works just like any other flip-flop — there are set and reset pulses, and a feedback loop to keep the whatever state the output is in alive. The key difference here is the addition of a clock signal. This clock, along with a few capacitors and a pair of diodes, give this single transistor the ability to store a single bit of information, just like any other flip-flop.

This is, without a doubt, a really, really weird circuit but falls well into territory that is easily understood despite being completely unfamiliar. The key question here is, ‘why?’. [roelh] says this could be used for homebrew CPUs, although this circuit is trading two transistors for a single transistor, two diodes, and a few more support components. For vacuum tube-based computation, this could be a very interesting idea that someone at IBM in the 40s had, then forgot to write down. Either way, it’s a clever application of diodes and an amazing expression of the creativity that can be found on a breadboard.

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Tesselated Worklights Are Nifty, Modular

Electric lighting – is there anything it can’t do? Coming in all manner of forms and flavours, you can get everything from a compact reading lamp to a blindingly powerful worklight for your garage. Generally, different lights are built in different ways to suit their purpose, but it’s not the only way to do things. Enter [slisgrinder] and the MOSAIC Lighting System.

At its heart, MOSAIC is a way of building lighting rigs out of individual modules. Where it gets interesting is the design – they’re triangles! The boards carry a variety of LEDs and are laid out in a fashion that allows the power and data connections to be made between adjacent cells by laying them out next to each other.  Many boards can be tesselated together to create larger, smaller, or unusually shaped arrays. The connections are well thought out, allowing the tiles to make a connection along any one of their 3 edges, regardless of orientation.

The project began out of a desire to grow okra in an otherwise inhospitable climate; to this end, there are both general work lighting modules as well as grow light versions with UV LEDs on board. The modules can be combined in different ways and command and control is done over RS-485.

It’s a tidy project that shows how a little thought can create a versatile design through the use of an unusual form factor. We’ve seen modular lighting projects before, too – like this entry to last year’s Hackaday Prize.

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When Hackerspace Directors Burn Out

A friend of mine once suggested that there should be a support group for burned-out former hackerspace directors. We could have our own Village of the Damned at summer camps, where we’d sit moodily in the gathering twilight sipping our bourbon and Club Mate and decrying whatever misfortunes came to our space to leave such visible mental scars, or gazing hollow-eyed into the laser-tinged haze and moving gently to the pulse of the chiptune music. “See that’s Jenny over there, she don’t say much“. Hackerspace noir, where the only entry criterion is being crazy enough to stand for election to your space’s board.

You can tell [Dr. Seuss] is thinking about his next volume: <em>How The Grinch Stole Whoville Hackspace</em>. Al Ravenna, World Telegram [Public domain].
You can tell [Dr. Seuss] is thinking about his next volume: How The Grinch Stole Whoville Hackspace. Al Ravenna, World Telegram [Public domain].

There must be spaces somewhere that live in such perfect harmony, in which a happy membership support a board for whom everything falls into place. Maybe the makerspace in [Dr. Seuss]’s Whoville would have that kind of atmosphere, but the reality of life is that every group is made up of both Grinch and Who. Keeping a diverse group of people harmonious is a huge challenge, but that’s what hackerspaces are really about — the people make the space.

There are several defined periods in the gestation of a hackerspace, and at least from where I’m sitting they relate to its member count. Some spaces pass through them all as they grow, while others are lucky enough to reach an equilibrium and spare themselves some of the drama.

If you recognise yourselves in some of the following then you have my commiserations, while if your space hasn’t got there yet or has managed to dodge some of the bullets then consider yourselves lucky.

In The Beginning, You Are a Tight Group of Friends

When a space or indeed any other community group first starts, it often does so through the hard work of a close band of friends. Ten or so people can achieve miracles, and many a small hackerspace has reached its first incarnation in this manner. If you are a member of a space at this level it is likely that you are strongly committed to its successful establishment, and you and your friends achieve much in reaching that aim. You establish your founding principles, which in many traditional hackerspaces include a very flat management tree in which transparency and openness are the key, with decisions reached by consensus because you are but a small group of friends who share a common aim.

As your space grows into the tens of members the initial spirit and camaraderie survive. Being a member of a space at this stage is fantastic, because with twenty or thirty members everyone knows each other and the group is small enough to work out any differences. Many smaller spaces never grow beyond this scale, and retain some of the best experiences in our sphere as a result. If you have one of these spaces in your area, join it. (But not too many of you, because of course if that happens the space will outgrow this happy state.)

I have no idea whether Electrolab as shown through [Mitch Altman]'s lens is the kind of harmonious space I wish I could be a member of, but seeing their members happily collaborating on a project fair brings a tear to my eye it does. [CC BY-SA 2.0]
I have no idea whether Electrolab as shown through [Mitch Altman]’s lens is the kind of harmonious space I wish I could be a member of, but seeing their members happily collaborating on a project fair brings a tear to my eye it does. [CC BY-SA 2.0].

At some point, usually around the fifty member mark, something changes. The original highly motivated group becomes diluted, and as the numbers increase a point is reached at which not everyone knows each other. It’s not that fifty people are not a number that you can know personally, simply that with the membership of a space all having their own timetables it is inevitable that after a while there will be people who will not be in on the same evenings as you.

Evolving Into An Organization

Your community starts to become broader, and somehow the space loses momentum, as the enthusiasm of the tight-knit group of early members is diluted. The ratio of active contributors to passive members plummets, while at the same time the number of loud voices who contribute little climbs inexorably.

If the space is lucky enough to have a good location with a ready demand for its services, it is inevitable that it will attract a steady stream of new members. Among them will be a number of motivated people who will put in the work required to make things happen, and eventually as the space moves into a three-figure number of members they replenish the hard core of net contributors until it moves into a second wind and becomes self-sustaining again. The doldrums have passed, and the future looks great. Well done if you are a member of a space in this position.

This piece is not however about that hackerspace in Whoville where everything goes well, instead we are more interested here in those spaces that falter along the way. What forms the battle scars of our burned-out directors from the Village of the Damned, and what can other members learn from their experiences? In exploring this particular avenue we aren’t even looking at the problems of a hackspace as such, instead since we are looking at the dynamics of a community. A lot of the lessons can just as easily be drawn from almost any club, society, or group.

Are You Building Stuff, or Building a Perfect Government?

One way in which you might classify members of any given group could be in terms of their motivation in being a part of it. Are they interested primarily in the purpose of the group, or in the way it is run? So in a hackerspace, are they focused on learning things and building stuff, or is it the ethos of the movement or the space’s management structure on which they focus?

This is an important classification to make because it encapsulates the purpose of a hackerspace. The hackerspace should exist to provide its members with facilities. Where a group starts to get into trouble is when focus is turned to making the group a perfect example of whatever political power structure floats their boat. If the membership becomes more interested in maintaining or tinkering with the structure of the organisation rather than providing its core function then it is inevitable that cohesion within it will fall down.

Power to the people! Wait, aren't we all the people? Che Guevara picture from Jgaray, after Alberto Korda [Public domain].
Power to the people! Wait, aren’t we all the people?
 Jgaray, after Alberto Korda [Public domain].

When the structure and ethos of the organisation becomes more important to a section of its members than its core service it often puts that section at odds with the board of directors. This can feel like a group of rebels who see themselves as the Popular Liberation Front against the Evil Tyranny of the board or committee or whoever is running the show.

In hackerspaces these groups inevitably coalesce around an ideal of an entirely consensus-driven hackspace collective, against which the board is portrayed as distant and dictatorial. The reality is that with growth, the consensus model is not longer feasible and the board are simply trying to get some work done.

This type of strife threatens the stability of the organization. As volunteers thrust into a stressful situation, the directors may begin to lighten their work load — the business of keeping the space functioning. It is easy to sound sane and reasonable when you are in opposition and have little work to do, but very difficult to get to grips with the job in hand when you achieve a position of power. The would-be [Che Guevara] is revealed as having more of the [Wolfie Smith] about them.

What Happens If No One Leads?

A hackerspace that has gone sour in this way will have an embattled and burned-out directorship under constant attack from a membership faction who believe themselves to be holding their executives to account. Sometimes this behavior crosses the line into outright harassment, and other times it just serves to wear down the energy of what is a volunteer board of directors. The organization may pull through and survive to fight another day with the arrival of those motivated new members mentioned earlier, but it may equally cave in as the embattled board gives up and the freedom fighters prove to be more adept at rabble-rousing than dealing with arcane questions of tool insurance. If this has happened to you then I know your pain, and rather than feeling bitter it is of more value to look at how such things might be avoided.

The consensus model can be a relatively successful one in a small-to-medium sized space, but it is noticeable that larger spaces have invariably set their early ideals aside and adopted a more top-down structure. If you are happy sitting through a six-hour meeting in which your resident pedant and idealogue slogs out the minutiae of an inconsequential point relating to your ethical doormat policy then perhaps your space could stay true to its early ideals, but for most members that rapidly gets old. For the most successful large spaces, well thought-out bylaws specify how decisions are made in a fair an equitable way that includes input for members without getting bogged down in endless bureaucracy.

Managing Hackerspace Leadership

So your organisational structure has become more top-down, you have a board of directors, and you’re ready to run your space. How do you ensure that your board is effective in its work? You’ve ensured that your director’s terms are staggered, you have just the right number of them, and you hope that your directors are proven contributors to the space. You can get down to meeting, right? You can deputise everything, hand out tasks which can then be project managed.

Don't tell me you've never been tempted during a hackerspace board meeting. BrokenSphere [CC BY-SA 3.0]
Don’t tell me you’ve never been tempted during a hackerspace board meeting. BrokenSphere [CC BY-SA 3.0]

One of the most unproductive things I have ever taken part in as a member of a hackerspace was over-frequent and regular board meetings. My and the other directors’ week became one of working towards things for the meetings rather than getting things done, so of course the board’s efficiency dropped like a stone while we were pursuing that course. You might be asking why we couldn’t manage to do such a straightforward thing, and you’d be perfectly correct to do so.

The answer lies in the nature of hackerspaces. The directors are not professional directors but everyday members who are trying to make their space better. They are giving up their limited time for free and like amateurs at any job, they sometimes make mistakes. And if the directors are volunteers then the members are doubly so, they haven’t made the same time commitment to running the space and neither should they be expected to unless they want to. Any idea that the board can simply deputise everything to members thus starts to fall apart when those members are found to have lives outside the hackerspace and thus little extra time in which to be given work.

In a company where there is funding to pay employees to do the board’s bidding this is a very successful model, but not in a voluntary organisation. The body of work falls upon the directors, the small number of members prepared to put in the time, and inevitably a member or two who volunteers for the work but doesn’t deliver. Because the directors are busy preparing for meetings most of the time they don’t have the time for everything though, so things start to slip and the members become upset That’s when you start your slide towards burn-out and a date with a bourbon and Club Mate in that village I was talking about.

Find the Right Balance for Your Hackerspace

As a member of more than one space and friend to members of many others I’ve watched the progress of more than one burned-out board. It’s not inevitable for this to happen by any means, but since hackerspaces can sometimes be prone to unfeasible levels of drama then it remains a distinct possibility. Given my outlook then, what would I wish for from my perfect hackerspace? Probably a smaller space, with decent local amenities, in a place that can draw members over a wide area. The more diverse the membership in age, gender, and background, the more experiences come together to make a better whole.

There’s one thing though, when I find my perfect space, would I stand to be a director again? After reading this I doubt my fellow members would vote for me anyway, but maybe not. Someone must do it for the good of the space, will you answer the call?

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