Vintage Slide Viewers Make Beautiful Retro Emulators

April 21, 2019 by 6 Comments

35mm still photography is still hanging on out in the wild, with its hardcore fans ensuring it never quite dies out despite the onward march of digital imaging. Slides are an even more obsolete technology, forgotten long ago when the quality of color negative films improved. The related paraphernalia from the era of the photographic slide continues to clutter up attics and garages the world over. [Martin Burlus] was in possession of some retro slide viewers, and found they made an excellent basis for a RetroPie build.

The build relies on stock standard fundamentals – a Pi Zero runs the show, combined with a USB hub and a power supply. [Martin] then chose to build this all inside the case of the slide viewer, combined with a 2.8″ PiTFT display. This neatly slots directly on to the Pi Zero’s 40-pin header, and comes complete with a touch screen. It’s the perfect size to slide into most slide viewers, though some models required removal of the tact buttons.

The slide viewers make for a charming enclosure, and the classic 1970s optics make for pleasant viewing. Throwing a modern display behind a vintage lens is a great way to give a project a more classic look and feel. One thing’s for sure – we’ll be keeping an eye out for a slide viewer of our own next time we’re passing through the local junk shops.

What’s The Secret Of Cyphercon?

April 21, 2019 by 5 Comments

Cyphercon is not particularly large, or in a glamorous part of the world — in fact most people who came in from out of town had to fight snow to make it. Yet when I stepped into the con last Thursday there was no doubt something awesome was in progress. People were camped out in small groups, working furiously on their computers, talks were packed with people who came alive in the Q&A, and everywhere you looked you found people deep in conversation with friends old and new. If you missed out on Cyphercon 4.0, you need to make an effort to be here for 5.0.

Join me after the break for the highlights of this two-day security conference nestled in the heart of Milwaukee.

Continue reading “What’s The Secret Of Cyphercon?” →

Characterising A Potentiometer With A Stepper Motor

April 21, 2019 by 16 Comments

Potentiometers, or variable resistors, are a standard component that we take for granted. If it says “10k log” on a volume pot, than we fit and forget. But if like [Ben Holmes] you are modelling electronic music circuitry, some greater knowledge is required. To that end he’s created a rig for characterising a potentiometer to produce a look-up table of its values.

It’s a simple enough set-up in which a voltage controlled current source feeds the pot while an Arduino with a motor controller turns it through a stepper motor, and takes a voltage reading from its wiper via an analogue pin. Probably most readers could assemble it in a fairly short time. Where it becomes interesting though is in what it reveals about potentiometer construction.

Audio potentiometers are usually logarithmic. Which is to say that the rate of change of resistance is logarithmic over the length of the track, in an effort to mimic the logarithmic volume response of the human ear in for example a volume control. If you are taught about logarithmic pots the chances are you’re shown a nice smooth logarithmic curve, but as he finds out in the video below that isn’t the case. Instead they appear as a set of linear sections that approximate to a logarithmic curve, something that is probably easier to manufacture. It’s certainly useful to know that for [Ben]’s simulation work, but for the rest of us it’s a fascinating insight into potentiometer manufacture, and shows that we should never quite take everything for granted.

Continue reading “Characterising A Potentiometer With A Stepper Motor” →

Concrete Table Even Includes A USB Hub

April 21, 2019 by 16 Comments

When designing furniture, material choice has a huge effect on the character and style of the finished product. Wood is a classic option, while more modern designs may use metal, plastic or even cardboard. Less popular, but no less worthy, is concrete. It’s heavy, cheap, and you can easily cast it into a wide variety of forms. [KagedCreations] thought this would be ideal, and whipped up this nifty piece of furniture with an integrated USB hub.

A pair of melamine shelves were scrapped to build the form, in which the concrete table is cast. Melamine is a popular choice, as it’s cheap, readily available, and releases easily from the finished concrete. Along with the USB hub, a wooden board is cast into the base of the concrete table top. This serves as an easy attachment point for the pre-made hairpin-style legs, which can be installed with wood screws.

The final result is a tidy side table that has plenty of heft to keep it stable and secure. It’s not the first concrete USB hub we’ve seen, but it’s likely the heaviest thus far. We’d love to see a version with an integrated charging pad, too – if you build one, be sure to let us know. Video after the break.

Continue reading “Concrete Table Even Includes A USB Hub” →

Watch These Two Robots Cooperate On A 3D Print

April 20, 2019 by 16 Comments

Putting a 3D printer on a mobile robotic platform is one thing, but two robots co-cooperatively printing a large object together is even more impressive. AMBOTS posted the video on Twitter and we’ve embedded it below.

The robots sport omnidirectional wheels and SCARA format arms, and appear to interact with some kind of active tabletop to aid positioning. The AMBOTS website suggests that the same ideas could be used for other tasks such as pick and place style assembly work, and the video below of co-operative 3D printing is certainly a neat proof of concept.

As a side note: most omni wheels we see (such as the ones on these robots) are of the Mecanum design but there are other designs out there you may not have heard of, such as the Liddiard omnidirectional wheel.

Continue reading “Watch These Two Robots Cooperate On A 3D Print” →

Dollar Store Garden Lights As ATtiny Power Supplies

April 20, 2019 by 19 Comments

Solar garden lights are just another part of the great trash pile of our age, electronics so cheap as to be disposable. Most of you probably have a set lurking somewhere at home, their batteries maybe exhausted. Internally though they are surprisingly interesting devices. A solar cell, a little boost converter chip, and a little NiCd battery alongside the LED. These are components with potential, as [Randy Elwin] noted with a mind to his ATtiny85 projects.

The YX805A chip he references in his write-up is one of several similar chips that function in effect as joule thieves, extending the available charge in the battery to keep the LED active as long as possible when their solar panel is generating nothing, and turning it off in daylight when the panel can charge. Their problem is that they are designed as joule thieves rather than regulators, so using them as a microcontroller PSU without modification can result in overvoltage.

His solution is to use the device’s solar panel input as a feedback pin from his ATtiny, allowing the microcontroller to keep an eye on its supply voltage and enable or disable the converter as necessary while it keeps running from the reservoir capacitor. Meanwhile the solar panel now charges the NiCd cell through a single diode. It’s not perfect and maybe needs a clamp or something, he notes that there is a condition in which the supply can peak at 8 volts, a level which would kill an ATtiny. But still, we like simple hacks on dollar store parts, so it’s definitely worth further investigation.

This isn’t the first garden light hack we’ve shown you, there was this flashlight, and some LED hacks.

Solar light picture: Leon Brooks [Public domain].

Cement Shelves Double As USB Hub

April 20, 2019 by 13 Comments

Some of us are able to get by in life with somewhere between 0 and 1 USB ports. We typically refer to these people as “Mac users”. For the rest of us, too much is never enough, and we find ourselves seeking out expansion cards and hubs and all manner of perverse adapters and dongles. [JackmanWorks] was a man who found himself in need of more connectivity, so he built this beautiful shelf with an integrated 12-port hub.

Material choice is key here, with this build looking resplendent in mahogany and cement. As the core of the build, the USB hub is first disassembled and sealed up to prevent damage from the cement. Hot glue is used to protect the PCB, while electrical tape helps cover the individual ports. The cement is then poured into a form which creates the overarching structure for the shelf, with the USB hub being cast in place. With the cement cured, mahogany boards are then cut and waxed, before installation into the structure. These form the individual shelves which hold phones, hard drives and other USB accessories.

The shelf was designed so that the entire structure is supported through the bottom shelf, which then sits on top of the desktop computer case. It’s an attractive piece, and the weight of the cement construction makes it pleasantly stable in use. It’s rare, but we do occasionally see shelf hacks around these parts. Video after the break.

Continue reading “Cement Shelves Double As USB Hub” →