A Baudot Code Speaking Chatterbot With A Freakish Twist

April 26, 2022 by Dave Rowntree 2 Comments

[Sam Battle] known on YouTube as [Look Mum No Computer] is mostly known as a musical artist, but seems lately to have taken a bit of shine to retro telecoms gear, and this latest foray is into the realm of the minicom tty device which was a lifeline for those not blessed with ability to hear well enough to communicate via telephone. Since in this modern era of chatting via the internet, it is becoming much harder to actually find another user with a minicom, [Sam] decided to take the human out of the loop entirely and have the minicom user talk instead to a Raspberry Pi running an instance of MegaHal, which is 1990s era chatterbot. The idea of this build (that became an exhibit in this museum is not obsolete) was to have an number of minicom terminals around the room connected via the internal telephone network (and the retro telephone exchange {Sam] maintains) to a line interface module, based upon the Mitel MH88422 chip. This handy device allows a Raspberry Pi to interface to the telephone line, and answer calls, with all the usual handshaking taken care of. The audio signal from the Mitel interface is fed to the Pi via a USB audio interface (since the Pi has no audio input) module.

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Copper: Rectifying AC A Century Ago

April 20, 2022 by Dave Rowntree 34 Comments

[Robert Murray-Smith] presents for us an interesting electronic device from years gone by, before the advent of Silicon semiconductors, the humble metal oxide rectifier. After the electronic dust had settled following the brutal AC/DC current wars of the late 19th century — involving Edison, Tesla and Westinghouse to name a few of the ringleaders — AC was the eventual winner. But there was a problem. It’s straightforward to step down the high voltage AC from the distribution network to a more manageable level with a transformer, and feed that straight into devices which can consume alternating current such as light bulbs and electrical heaters. But other devices really want DC, and to get that, you need a rectifier.

It turns out, that even in those early days, we had semiconductor devices which could perform this operation, based not upon silicon or germanium, but copper. Copper (I) Oxide is a naturally occurring P-type semiconductor, which can be easily constructed by heating a copper sheet in a flame, and scraping off the outer layer of Copper (II) Oxide leaving the active layer below. Simply making contact to a piece of steel is sufficient to complete the device.

Obviously a practical rectifier is a bit harder to make, with a degree of control required, but you get the idea. A CuO metal rectifier can rectify as well as operate as a thermopile, and even as a solar cell, it’s just been forgotten about once we got all excited about silicon.

Other similar metallic rectifiers also saw some action, such as the Selenium rectifier, based on the properties of a Cadmium Selenide – Selenium interface, which forms an NP junction, albeit one that can’t handle as much power as good old copper. One final device, which was a bit of an improvement upon the original CuO rectifiers, was based upon a stack of Copper Sulphide/Magnesium metal plates, but they came along too late. Once we discovered the wonders of germanium and silicon, it was consigned to the history books before it really saw wide adoption.

We’ve covered CuO rectifiers before, but the Copper Sulphide/Magnesium rectifier is new to us. And if you’re interested in yet more ways to steer electrons in one direction, checkout our coverage of the history of the diode.

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Gridfinity: 3D Printed Super Quick Tool Storage And Retrieval

April 18, 2022 by Dave Rowntree 32 Comments

Our favourite cyborg [Zack Freedman] has been stumbling over a common problem many of us will be all too familiar with — that of tool storage and the optimal retrieval thereof. His solution is the Gridfinity: A modular workshop organisation system.

Never chase your pen around on the desk again

In [Zack]’s words, the perfect workshop has tools and materials arranged in the following way: (a) every item has a dedicated home within reach of where you’ll use it. (b) items are exposed and in position for instant grabification. (c) the storage system shields you from accidents like spills and injuries. (d) it is effortless to setup and easy to put back and rearrange. An instant-access storage solution such as the Gridfinity is designed not to help you store more stuff, but finish more projects. The idea is very simple — display your stuff so that you can quickly find what you need and get back to the project as quickly as possible. We think these aims are pretty spot on!

From an implementation perspective, the system consists of a 3D printed base plate with a grid structure. It is angled internally so storage bins drop in, but are not easy to knock out. Storage units drop into the grid in various sizes and orientations, such that everything is contained within the grid’s outer boundary, so the whole assembly will fit inside a drawer with ease. Small part storage bins have a curved inner surface enabling one to easily scoop out a part when required. A partial lid on the top allows them to be stacked vertically if required.

Super-quick access to fully sorted stock – no more searching

Whilst the system is work in progress, there are still about a hundred different storage units, for anything from 3D printer nozzles to racks for tweezers. Implemented as parameterised models in Fusion360, it is easy to tweak existing models for your stuff, or create totally new ones, from the supplied templates.

No discussion of tool organisation would be complete without first considering the king of tool organisation [Adam Savage], the principle of first order retrieval is a strong one. For a more in-your-face solution, you could go down the pegboard-on-wheels route, or perhaps if you’re less mobile and in a tight squeeze, then get comfortable with the French cleat and build something full custom right into the walls. Whatever solution you come up with, do share it with us!

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NASA Hardware Techniques: Soldering Space Electronics Like It’s 1958

April 13, 2022 by Dave Rowntree 44 Comments

[PeriscopeFilms] on YouTube has many old TV adverts and US government reels archived on their channel, with some really interesting subjects to dive in to. This first one we’re highlighting here is a 1958 film about NASA Soldering Techniques (Video, embedded below), which has some fascinating details about how things were done during the Space Race, and presumably, continue to be done. The overall message about cleanliness couldn’t really be any clearer if they tried — it’s so critical it looks like those chaps in the film spend far more time brushing and cleaning than actually wielding those super clean soldering irons.

Of particular note are some of the details of wire stripping and jointing with components, such as the use of a hot-wire device to remove the insulation from wire, rather than use the kind of stripper we have lying around that cuts into the insulation and slightly distorts the wire in the process. That just won’t do. If they did have to use a cutting-type stripper, it must be precisely the right size for job, and calibrated daily.

The road to the Moon is paved with calibrated wire strippers.

When soldering a pre-tinned wire to a leaded component, a clamp is required to prevent movement of the wire, as is a thermal shunt on the component lead to protect the delicate component from excess heat. They even specify how much to wrap a wire around a terminal to be soldered, never bending the wire more than 180 degrees.

The bottom line in all this is, is that the work must be as perfect as is possible, as there is very little chance of sending someone up to fix a dodgy soldering job, once the assembly is hurtling around the planet. They call it too much of a science to be called an art and too much art to be called a science, and we can sure appreciate that.

As you would expect (and it’s not exactly a big secret) NASA has some very exacting standards for assembly of all hardware, like this great workmanship standard, which is well worth studying. Soldering is an important subject for many of us, we’ve covered the subject of solder metallurgy, as well as looking at how ancient hardware hackers soldered without the benefit of much modern knowledge.

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A V2 Rocket Inspired Steam Turbine Skateboard Is Just Around The Corner

April 12, 2022 by Dave Rowntree 19 Comments

[Integza] never fails to amuse with his numerous (and sometimes really sketchy) attempts to create usable thrust, by pretty much all means possible and the latest video (embedded below) attempting to run a reaction turbine from decomposing hydrogen peroxide, doesn’t fail to disappoint. The inspiration came from the WWII V2 rocket, which used Sodium Permanganate to breakdown Hydrogen Peroxide. This produced high pressure steam, which spun a turbine, which in turn drove the turbopumps that delivered the needed huge quantity of alcohol and liquid oxygen into the combustion chamber.

After an initial test of this permanganate-peroxide reaction proved somewhat disappointing (and messy) he moved on to a more controllable approach — using a catalytic converter from a petrol scooter in place of the messy permanganate. This worked, so the next task was to build the turbine. Naturally, this was 3D printed, and the resulting design appeared to work pretty well with compressed air as the power source. After scaling up the design, and shifting to CNC-machined aluminium, it was starting to look a bit more serious. The final test shows the turbine being put through its paces, running from the new precious metal catalyst setup, but as can be seen from the video, there is work to be done.

There appears to be a fair amount of liquid peroxide passing through into the turbine, which is obviously not desirable. Perhaps the next changes should be the mount the catalyser vertically, to prevent the liquid from leaving so easily, as well as adding some baffling to control the flow of the liquid, in order to force it to recycle inside the reaction vessel? We can’t wait to see where this goes, hopefully the steam-turbine powered skateboard idea could actually be doable? Who knows? But we’re sure [Integza] will find a way!

With steam power, there’s more than one way to get usable rotational work, like using a reciprocating engine, which can be expanded to a whole machine shop, and whilst boiling water (or catalytically decomposing Hydrogen Peroxide) provides high pressure gas, how about just using boiling liquid nitrogen? Possibly not.

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Quick Hacks: Countersinking Screw Heads With 3D Laser Engraving

April 11, 2022 by Dave Rowntree 19 Comments

Here’s a fun quick hack from [Timo Birnschein] about using the 3D laser engraving (or ‘stamp’ engraving) mode of certain laser cutter toolchains to create a handy countersink shape in a laser-cut and engraved workpiece. Since [Timo] uses a small laser cutter to cut out and mark project boards for their electronics builds, having an extra messy, manual countersinking operation with subsequent clean-up seemed like a waste of time and effort, if the cutter could be persuaded to do it for them.

Designs are prepared in Inkscape, with an additional ‘3D engraving’ layer holding the extra processing step. [Timo] used the Inkscape feathering tools to create a circular grayscale gradient, leading up to the central cut hole (cuts are in a separate layer) which was then fed into Visicut in order to drive the GRBL-based machine, However, you could do it with practically any toolchain that supports laser power control during a rastering operation. The results look perfectly fine for regions of the workpiece not on show, at least, but if you’re only interested in the idea from a functional point of view, then we reckon this is another great trick for the big bag of laser hacks.

There have been a great number of laser cutting hacks here over the years, since these tools are so darn useful. The snapmaker machine can be a 3D printer, a CNC cutter and a laser cutter all in one, albeit not too perfect at any of those tasks, but the idea is nice. If you own a perfectly fine 3D printer, but fancy a spot of laser engraving (and you have good eye protection!), then you could just strap a 5W blue diode laser to it and get your fix.

A Super Simple DIY Ozone Generator

April 10, 2022 by Dave Rowntree 38 Comments

[Advanced Tinkering] needed a source of fresh ozone for some future chemistry related projects, and since buying an off-the-shelf unit would be, well, just plain boring, it was obvious what to do (Video, embedded below).

Wire mesh discharge surfaces separated with a glass tube

The concept of the corona-discharge ozone generator is pretty straightforward — a high-voltage AC potential is presented over a large surface area, such that any O₂ in the vicinity has the chance to get a decent dose of electrons ripping it apart and enabling the formation of the desired O₃.

The construction is quite simple, just a pair of cylindrical metal wire mesh electrodes, separated by a glass tube, with a second glass tube surrounding the whole assembly. The use of high voltage AC allows the discharge to form by capacitive coupling across the central tube, giving a very simple construction. A pair of 3D-printed PLA end caps complete the reaction vessel, although it is noted in the video that the PLA is not terribly resistant to the corrosive effects of ozone, and time will tell whether these go the whole mileage.

Feed oxygen from an external generator is pumped into one end cap, at the bottom, with ozone-enriched gas passing out the other end, at the top, giving the gas a more complex path through the assembly and maximizing the contact with discharge. It will be interesting to see what the produced ozone will be used for in these future projects.

We’ve not seen a vast number of ozone hacks, but we’re no strangers to high voltage applications, like this interesting hand disinfection device, and this simple hack that generates a six-figure voltage with little more than some glasses of water, well not much more anyway.

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