classic hacks

2658 Articles

7 Segment Clockwork Display Made From Cardboard

October 31, 2018 by 25 Comments

We’ve seen a variety of oddball 7-segment displays in the past, but this one uses a new material: both for the display and the mechanical mechanism that drives it; cardboard. Yup, the whole thing is made from cardboard, wood and a few rubber bands. [The Q] shows how he put together in this nice video, starting from first principles that show how the segments are made: simple pieces of cardboard painted on one side with fluorescent paint. A piece of wood pushes the element out to blank it, and each element is connected to a cam wheel that pushes the wood in or out.

The really clever bit is that [The Q] mapped digits 0 – 9 onto a matrix for which of the 7 segments is “on” or “off”. He then used this information to create a stack of 7 cams on a central axle. As you rotate the axle, the cams turn, moving the wooding arms. The arms then cause the elements to flip as they count up through the digits. In essence, he engineered a physical decimal to 7 segment decoder, much like the electronic one inside the SN74LS47. The whole assembly is capped by a knob that indicates which digit is currently displayed. If mechanical displays like this are your thing, check out this one made from LEGO parts, or this awesome 3D printed creation.

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Child’s Pushcar Gets Serious Horsepower

October 26, 2018 by 10 Comments

A pushcar is a great toy for a young child. They’re great excercise, and kids love anything on wheels. However, the bigger kids might want something with a little more grunt. [Master Milo] has just the thing – an engine from a concrete saw and the fabrication skills to match. (YouTube, embedded below.)

The build starts with the disassembly of the concrete saw, with covers, the saw drive and handle all removed. This leaves a 70 cc petrol engine with a centrifugal clutch already fitted. A steel frame is then built around the engine to mount the rest of the drivetrain. An intermediate shaft is used at the rear to allow for an extra level of gear reduction, and steering up front is handled with parts cribbed from an old ATV. The plastic shell of the pushcar is then fitted over the top and a seat constructed out of scrap wood.

Mechanical parts are in ready supply, with bearings and shafts all sourced from INDI, a European equivalent to McMaster Carr. By purchasing gears, belts and other parts off the shelf, it’s easy to make something that fits first time with a minimum of modification required.

The testing video is worth a watch – with both top speed and handling tests. The platform’s handling does leave something to be desired, but that’s half the fun in a build like this.

We’re no strangers to these projects around these parts – a modded Power Wheels is a great electric take on the same concept. Continue reading “Child’s Pushcar Gets Serious Horsepower” →

DIY Tuning Capacitors From Washers And 3D-Printed Parts

October 25, 2018 by 34 Comments

The inside of classic radios holds wonders that the sterile chips and SMD components of today’s circuits can’t hold a candle to. Chunky resistors and capacitors, vacuum tubes with cathodes aglow, and seemingly free-form loops of wire forming inductors will all likely make an appearance. But the most fascinating bit of any old radio was connected to the tuning knob: the big variable capacitor with its interdigitating metal plates. Watching one at work, with its plates evenly and finely spaced, is still a joy to behold.

In an attempt to recapture a little of that magic, [Jeremy S. Cook] came up with this home-brew variable tuning capacitor. The frame is built mainly from 3D-printed parts, which supports a shaft made from a common bolt. Plates are fashioned from stainless steel fender washers cut in half; the fixed plates are press-fit into the frame while the rotary plates ride on the shaft. The spacing between the rotary plates is maintained by printed spacers, which also serve to lock the rotor into one solid unit. [Jeremy]’s prototype, for which he provides STL files, can be tuned between about 7 and 15 pF. Check out the build in the video below.

We love the look of this, and we can imagine custom tuning caps would come in handy for certain retro radio builds. The tuning range is a little narrow, but that could be fixed with more plates or closer spacing. That might be a tall order with thick steel washers, but we’ve seen really thin aluminum machined and closely spaced before, so this might be one approach to higher capacitance. Continue reading “DIY Tuning Capacitors From Washers And 3D-Printed Parts” →

Camera Obscura On Wheels Hits The Open Road

October 24, 2018 by 19 Comments

A camera obscura is a very simple device. Consisting of a dark chamber, with only a pinhole to let light in, it focuses an image on its inside surface. If you want to take a permanent copy, it’s as simple as installing a photosensitive film inside and managing the exposure time. Sounds like a normal camera, right? The difference is the scale —  a camera obscura is large enough that humans can stand inside and view the image. Usually, they are large stationary rooms. [Physics Girl] took the show on the road by building a camera obscura out of a rented box truck.

The optics of the camera obscura project an image upside-down.

The basic concept is a great one – hire a box truck, and cover the rear opening with cardboard. Cut a small hole in the cardboard, and you’ve created a camera obscura on wheels. The video does a great job of explaining the optical principles behind what’s happening, and there’s even experimentation around how to change the exposure level and focus through modification of the aperture.

The only downside to viewing a camera obscura on video is that you can’t appreciate the resolution and detail visible in real life. Trust us though, it’s better than any HDTV on the market today.

The rolling camera obscura makes for a great experiment which requires little more than some cardboard, tape, and a sunny day. It would be great fun to execute as an educational activity at a school or makerspace. Once you’ve tackled that, perhaps consider the digital version. Video after the break.

[Thanks to Baldpower for the tip!]

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Racing The Beam And Dropping Some Beats

October 23, 2018 by 5 Comments

The heart of the Atari 2600 wasn’t the 6502 (or the 6507 for the pedants), it was the TIA chip. This is the chip responsible for drawing graphics on the display, racing the beam, and extremely limited support for sound generation. We haven’t seen many attempts of using the Atari 2600 for chiptunes, but that doesn’t mean it can’t be done. [John Sutley]’s Syndrum, a take on an Atari 2600 drum machine is nearly a work of art. It’s a custom cartridge for the wood-paneled Atari, and an impressive input device that turns this classic console into a beat machine

Did the Atari 2600 ever come with a drum machine cartridge? Maybe. Probably not. [John] originally built this project to experiment with the TIA chip, but found it was less tonal than a kazoo. That struck ‘Atari synthesizer’ off the list and replaced it with an ‘Atari drum machine’. There are two key parts of the build here, the first being a repurposed Asteroids cartridge that had the PROM replaced with a ZIF socket. This allows [John] to easily burn new code to an EEPROM, stuff it in the socket, and run it on the Atari. All the code was developed with batari Basic, a BASIC-inspired language that spits out .bin files for the Atari.

But running code on the Atari is just one half of this build. To do a drum machine, you somehow need to tell the Atari when to play each sound. Given the lack of expansion capabilities for the Atari, [John] turned to the controller port. The Syndrum uses Arduino Nano to bridge the DE9 controller connector to a MIDI port. Yes, it’s real MIDI, on a machine that could probably never do MIDI natively (although we’d love to see someone try).

Need a video of this mind-blowing hack in action? Here you go:

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Slack On The SNES Via Satellite

October 23, 2018 by 14 Comments

We love seeing hardware and software from bygone eras getting a new lease on life through modern hacks, as longtime readers can surely attest to. Why leave this stuff to rot in a closet somewhere when it can be pushed into service today? Granted it might not always be the most efficient way to accomplish a task in the 21st century, but at least you’ll net some precious Internet Points for originality.

As a perfect example, take a look at this project which lets you read Slack messages through a Super Nintendo game. If your first thought was that such a thing would involve an unreasonable amount of effort and hoop jumping…then you would be correct. [Bertrand Fan] really had to think outside the box to make this one happen, and even admits a bit of imagination is required on the part of the end-user to use it. But it’s undeniably an original approach, so we hereby bestow the customary Internet Points unto him.

So how does this work, and where do the satellites come in? The key is in a fairly obscure Japanese SNES peripheral called the Satellaview, one of Nintendo’s early attempts at creating an online content delivery system for their consoles. Games designed with Satellaview support would be able to pull down new content from regular satellite broadcasts, not too bad for 1995. This means that if you have the hardware, and happen to own a satellite, you can push your own content into an unmodified SNES. No problem, right?

Alright, [Bertrand] didn’t really use a Satellaview modem plugged into an actual SNES. Plus we’re fairly sure he doesn’t have his own satellite network to broadcast Slack messages with anyway. But it turns out some SNES emulators have support for a virtual Satellaview modem, and there’s even software out there that will let you create new content “downloads” for the system’s included game: BS-X: The Story of The Town Whose Name Was Stolen. All he had to do was connect the dots.

[Bertrand] started by stripping the user interface out of SatellaWave, an open source tool for creating Satellaview content, so that it only need to be provided with an XML file of the content to be “downloaded” by the virtual satellite modem. Using the Slack API, he then came up with way to pull the last 10 messages from a server and push them into his modified version of SatellaWave. Each time somebody posts a new message his software kicks in to produce a new satellite download which automatically gets picked up by the SNES emulator and pops up in the game.

If this is still too practical for you, you can always go all in and run Slack on your Commodore 64.

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