There’s A Computer In This Hard Drive

July 7, 2018 by 21 Comments

Throughout the history of personal computers, there are some unique form factors. The 3com Audrey was sold as a computing appliance, meant to sit on a kitchen counter, to display recipes or something. For some reason, Macs were cubes once, and it actually wasn’t a bad machine. At one point, you were supposed to put a monitor on top of your computer.

A few years ago, [glitch] read about an interesting system from the early 80s. The SIIG S286 was designed by the same people that made SCSI cards and external hard drives, and it shows: this is a complete 286-based system stuffed into what was probably an external enclosure for a 5 1/4 drive at some point. After finding one of these bad boys on an auction site a few months ago, he finally got it working. It’s weird, but it can get on a network, and you can read Hackaday with it.

The entire computer is stuffed into a case that’s about 5″ wide, 4″ tall, and 10″ long. There’s a motherboard with built-in VGA, ‘game port’, and a printer port. There’s a riser card for real 16-bit ISA cards, two serial ports, and a connector for a hard disk and floppy drive. Basically, it’s an entire 286 system wrapped up in a tiny box.

After acquiring this machine, [glitch] took it apart and found the usual damage. The CMOS battery leaked, but not too bad. This was replaced with a hermetically sealed lithium thionyl chloride battery. These are non-rechargable, but a quick swipe of the soldering iron disable the motherboard’s charging circuitry. The hard drive was replaced with a 128 MB Flash module, and an Ethernet card was installed.

With that, [glitch] has a complete system that can connect to the Internet. Of course, getting on the Internet with a 286 is a challenge, but we have a Hackaday Retro Edition for just the occasion. The browser is Arache, with the mTCP package. That’s about as low as you can go in Intel-land, and excellent proof that the computer will work for another 35 years or so.

The PT2399 Delay/Echo Chip Data Sheet You Never Had

July 7, 2018 by 13 Comments

If you are fortunate enough to have had the opportunity to play with an analogue-reel-to-reel tape recorder in a well-equipped studio, you probably looped the tape around to create an echo, or a delay in the audio. It was a desirable effect to have, but not a practical one for a guitar pedal or similar portable accessory. Silicon alternatives for creating delays have been in production since the 1960s, first the so-called bucket brigade delay lines that used a switched chain of on-chip capacitors, and more recently all-digital chips that process the delay by storing samples in RAM. One of the more popular of those is the Princeton Technology PT2399, but it comes with something of a snag for the experimenter in the form of a sparse data sheet. Thankfully the folks at [Electrosmash] have come to the rescue on that front with a thorough technical examination of the chip that should fill in any gaps in the official documentation.

After a brief examination of the range of chips of which the 2399 is a part, they dive right into the chip’s internals by rearranging the internal circuit diagram from the data sheet to the point at which it makes more sense. At which point the difference between the chip’s delay and echo functions becomes obvious, through the inclusion of a feedback path.

We then are taken through the pins, examining what lies behind the power supply and analog inputs and outputs. We are somewhere between a data sheet and an app note here, as some of this is information rarely present even in really good data sheets. Finally, we are taken through the chip’s performance, with real-world distortion and noise measurements. Armed with this page, the would-be PT2399 designer really can say they know what they are working with.

Surprisingly few PT2399s have appeared on these pages, however one did pop up in the Synthbike.

Smart Power Strip Revived With Raspberry Pi

July 6, 2018 by 19 Comments

We’re all for buying broken stuff from eBay to save yourself a few bucks: buy it cheap, fix it, and reap the rewards of being a step ahead of the average consumer. Searching through the “For parts or not working” categories is nearly the official pastime here at the Hackaday Bunker. But buying an eBay find only to have it give up the ghost in a couple weeks? That hurts.

That’s precisely what happened to [idaresiwins] when he bought this beefy looking “Web Power Switch” on the Electronic Bay. After two weeks, the controller board blew and his “smart” power strip became very stupid indeed. But with the addition of a Raspberry Pi, he’s got it back up and running. Not only that, but given the extra horsepower this device now contains, it now doubles as a basic server for the home lab.

This conversion was helped by the fact that the original controller was on a separate board from the relays, and connected with a small ribbon cable. All [idaresiwins] had to do was figure out which wire in the cable went to each of the eight relays, and fire them off with the Pi’s GPIO pins. In an interesting detail, he opened up one of the ends of the ribbon cable and used it as a punch down block of sorts to easily hook the wires up to the Pi’s pins. We might suggest some hot glue to keep everything from moving around, but otherwise it’s a neat tip.

[idaresiwins] found some information online about making a web-based GPIO interface, which he adapted to control the outlets on the power strip. He then wrapped the Pi up in plastic to keep it from shorting out, and tucked it inside the case. Note that he was able to pull 5 VDC from the relay board and run it to the Pi over the ribbon cable, so he didn’t need to bother with hacking a USB adapter in there.

Controlling AC devices over the Interwebs is an extremely popular project, and we’ve even seen a DIY device that looks quite similar to this product. Most of them are now using the ESP8266, but with the Pi onboard this hack is more like a super-sized version of the PowerPwn.

Tinkercad Coding Tricks To Automate Modeling

July 6, 2018 by 19 Comments

If you want to do a quick design for 3D printing, Tinkercad is pretty easy to use. Although it was briefly in danger of going out of business, it was bought by AutoDesk who have made a lot of improvements. It is possible to program and simulate an Arduino in the same tool — which always strikes us as an odd juxtaposition. However, [Chuck] shows us in the video below how you can use the same Codeblocks to automate Tinkercad 3D modeling thanks to a beta feature in the software. Think of it as a GUI-based OpenSCAD in your browser.

You have to start a Codeblocks project, and when you do you can pick a starter design or just press the button for a new design to get a blank slate. The blocks look like other Scratch-related programming languages. You can create variables, repeat groups of commands, and create items. [Chuck] mentions the starter codes have no comments in them, which is a fair critique. There is a comment block you can use.

Continue reading “Tinkercad Coding Tricks To Automate Modeling” →

Dollar Store PCB Holder System

July 6, 2018 by 3 Comments

As you get into electronic fabrication and repair, one of the first things you realize is how hard it can be to hold a PCB still while you work on it. Securing them is difficult due to their very nature: they’re often weird shapes, quite fragile, and of course need to be electrically isolated. If you don’t mind spending the money, and have the time to wait on it getting delivered, you can order some nice purpose-built systems for holding PCBs online. But what if you need something fast and cheap?

[Paul Bryson] might have the solution for you. On his blog he’s documented how a trip to the dollar store and some parts from the junk bin allowed him to create a practical system for holding multiple PCBs of various shapes and sizes. The most exotic element of the build here are the hexagonal standoffs; and if you haven’t already salvaged a bunch of those from a curbside computer, he even gives the Mouser link where you can buy them new for a few cents each.

Each individual stanchion of the system is made up of a 3/4″ round magnet with a hex standoff glued to the top. Over the standoff, [Paul] slipped a rubber grommet which gives a nice non-conductive slot to put the edge of the PCB in. Otherwise, a second hex standoff screwed into the first can be used to clamp down on the board. Adjusting the height is as simple as adding a couple more magnets to the stack.

Of course, magnets need something metal to stick on. For that, [Paul] purchased some steel pie pans and matching rack from the dollar store. The round pans are easy to handle and give him plenty of surface area, and the rack makes for an exceptionally convenient storage unit for all the components. The conductivity of the pans might be a concern, but nothing the application of a rubberized spray coating couldn’t fix.

We’ve covered similar systems before, but this one certainly looks to take the top spot in terms of economics. The only thing that would be cheaper would be a few feet of PLA filament and a rubber band.

A 38-Year-Old Vocoder Project

July 6, 2018 by 12 Comments

It is hard to remember that scant decades ago, electronic magazines — the pre-Internet equivalent of blogs — featured lots of audio circuits based on analog processing. Music synthesizers were popular for example, because microcontrollers were expensive and unable to perform digital signal processing tasks in the way you would use them today. [Julian] has been trying to build a vocoder from that era from ETI magazine. Along the way, he’s making videos documenting what he’s found and how’s he resolving issues.

The circuit generates levels for particular input frequencies. It does so with a two-op-amp bandpass filter, a two-op-amp rectifier, and then an op-amp lowpass filter. That’s five op-amps for each band (there are 14 bands) plus the support circuitry. And that’s just the input section! Today, you would simply sample the signal and do a fast Fourier transform (FFT) to get the same kind of data.

Continue reading “A 38-Year-Old Vocoder Project” →

DIY Socket For Prosthetics Contains Power Supply, Charger

July 6, 2018 by 5 Comments

Innovation in prosthetics is open to anyone looking to enhance the quality of life, but there’s an aspect of it that is sometimes under-served. The DIY Prosthetic Socket entry to the Hackaday Prize is all about the foundation of a useful prosthesis: a custom, form-fitting, and effective socket with a useful interface for attaching other hardware. While [atharvshringaregt] is also involved with a project for a high-tech robotic hand with meaningful feedback, socket fitting and design is important enough to be its own project.

The goal is not just to explore creating these essential parts in a way that’s accessible and affordable to all, but to have them include a self-contained rechargeable power supply that can power attachments. Thoughtful strap placement and a power supply design that uses readily available components with a 3D printed battery housing makes this DIY prosthetic socket a useful piece of design that keeps in mind the importance of comfort and fitting when it comes to prosthetics; even the fanciest robot hand isn’t much good otherwise.

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