Sometimes Square Is Square: Basic Machinist Skills

October 25, 2016 by Dan Maloney 27 Comments

Is it possible to make an entertaining video about turning a cube of aluminum into a slightly cubier cube? As it turns out, yes it is, and you might even learn something along with the sight gags and inside jokes if you watch [This Old Tony] cover the basics of squaring up stock.

Whether you’re working in wood or metal, starting with faces that are flat, smooth and perpendicular is the key to quality results. [Tony] is primarily a machinist, so he works with a nice billet of aluminum and goes through some of the fundamental skills every metalworker needs to know. When you’re working down to the thousandths of an inch it’s easy to foul up, and tricks such as using a ball bearing between the vise jaws and the stock to prevent canting are critical skills. He covers tramming the mill, selecting which faces to cut and in which order, and ways to check your work on the surface plate and make any corrections if and when things go wrong. Look for cameos by fellow machinist [Abom79] and [Stefan Gotteswinter], including one with [Stefan] in a very compromising position. But a ball in a vise and no [AvE] reference? C’mon!

[Tony] makes a potentially tedious subject pretty entertaining by keeping things light, and we appreciate both the humor and attention to detail. He’s turned out some great videos that we’ve covered before, like making your own springs or a shop-built boring head, and his stuff is really worth checking out.

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Making A Cassette Mass Storage Interface

October 22, 2016 by Jenny List 55 Comments

If you are of the generation who were lucky enough to use the first 8-bit home computers in your youth, you will be familiar with their use of cassette tapes as mass storage. Serial data would be converted to a sequence of tones which could then be recorded using a standard domestic cassette recorder, this recording could then be played back into the machine’s decoder and loaded into memory as a complete piece of software. Larger programs could take a while to load, but though it was rather clunky it was a masterful piece of making the best of what was at hand.

[Mike Kohn] was working with some microcontroller infra-red communication projects when he saw that the same techniques could be used to produce a tape interface like those on the home computers of old.

Over the years he has returned to the project a couple of times, and his original Atmel processor has been supplanted by a W65C265SXB development board based on the 16-bit derivative of the 6502. This made generating the tones as straightforward using his processor’s built-in tone generator, but decoding still presented a challenge. His earlier attempts used an LM2917 frequency to voltage converter to decode tones to logic levels, but on further consideration he decided to move to the LM567 tone decoder. This chip is designed specifically for an on-off logic output rather than the 2917’s analogue voltage output.

His recording device was originally a hi-fi separate cassette deck after experimenting with microcassettes, but eventually he used a data recorder designed for a Radio Shack TRS-80. All his code can be found in his GitHub repository.

It’s probably true to say that [Mike] has made a better cassette interface than the one you could have found on your home computer back in the day. We’ve featured a few data cassette hacks over the years, including this Commodore tape deck with an LED counter, and a tape deck emulator capable of holding an entire software archive.

3D Print An Enigma Machine That’s Close To The Real Thing

October 21, 2016 by Jenny List 6 Comments

The Enigma machine as used by the German military during World War Two exerts a curious fascination among our community of hardware hackers and makers. Perhaps it is the mechanical complexity of the machine itself, or maybe the tale of how its encoded messages were decrypted by Allied codebreakers that contributes to this interest, but whatever it is we’ve seen a succession of Enigma-related projects over the years that shows no sign of abating.

The latest Enigma project to come our way is a particularly nice one from a group of first year students at CentraleSupélec Rennes, in Northwestern France. Their Réplique Enigma is a fully mechanical Enigma replica using 3D printing techniques, and unlike so many replicas which use modern electronics it has a set of rotors just like those you would have found in the original. The rotors themselves have a 3D-printed plastic shell which houses brass contacts and the associated writing, while the keyboard and lamp board are both made from plywood. Rather than trying to replicate the original switches from the keyboard they are using modern microswitches, however the keys themselves are upright posts that resemble the original. An AZERTY layout may not have been present on the real Enigma machines, but lends a pleasing twist to the build.

It’s worth browsing all the pages for this build, as the front page does not necessarily capture the whole build. The rotors set this Enigma apart from many of the replicas we’ve featured in the past, so you may find it interesting to take a look and make a few comparisons.

Dumb Terminals And Raspberry Pis

October 19, 2016 by Brian Benchoff 17 Comments

Back in the old days, the cool kids didn’t have an Apple II or a Trash-80. The cool kids had jobs, and those jobs had Vaxxen all over the place. The usual way of working with a Vax would have been a terminal, a VT220 at least, or in the case of [Sudos]’ experiments with a Raspberry Pi, A DEC VT510, a single session, text only serial terminal.

Usually, when we see a ‘new hardware stuffed into old tech’ project like this, the idea is simply to find a use for the old hardware. That makes sense; a dumb terminal from the late 90s should be a bit rarer than a Raspberry Pi Zero. This is not the case for [Sudos]’s build. He recently came across a few Raspberry Pi Zeros at Microcenter, and looking for a use for them, he decided to turn a serial terminal into a Real Unix System™.

As you would expect from a serial terminal, connecting a Raspberry Pi and putting some awesome character graphics on the screen is as simple as a Max3232 board picked up from eBay, a WiFi dongle, and an Ethernet adapter. Connect the Pi to the terminal with a serial adapter cable, and you’re off to the races.

While the VT510 serial terminal is just about the end of the line as far as dedicated terminals go, there are classier options. The VT100 terminal, older than most of the Hackaday readership, features a port on its gigantic board, meant to connect to whatever weirdness was coming out of Maynard in the late 70s. You can attach a BeagleBone to this connector, making for a very slick stealth mod.

Teardown A Classic : Tektronix P6042 Current Probe

October 16, 2016 by Gerrit Coetzee 6 Comments

[Paul Rako]’s teardown of his treasured P6042 current probe shows why Tektronix commands so much respect among the old hats of the electronics world.

Built in 1969, the P6042 is pretty sparse transistor-wise when compared a modern sensor. The user would clip the current probe, permanently attached to the case since the circuit was tuned for each one, over a wire and view the change in volts on an oscilloscope. When the voltage division on the oscilloscope was set properly the current in a circuit could be easily seen.

The teardown is of a working unit so it’s not completely disassembled, but it also sits as a nice guide on refurbishing your own P6043, if you manage to snag one from somewhere. Aside from capacitors and oxidized switch contacts there’s not much that can go wrong with this one.

As for how it compares, the linear power supply, analog circuit design, and general excellent engineering has the P6042 coming in with a cleaner signal than some newer models. Not bad for a relic! Do any of you have a favorite old bit of measurement kit?

Blinking An LED – Extreme Edition

October 13, 2016 by Nava Whiteford 57 Comments

This hacker’s video on blinking LEDs never got the recognition it deserves. At the time of writing clocking in at just 61 views, but it is indeed a work of art. Just trust me, scroll to the bottom of the article and watch it, you wont be disappointed.

Not convinced? OK, let me tell you about it and the world it has opened up in the Japanese maker scene. We’ve all blinked an LED. Maybe it was just to test a microcontroller, like the simplest Arduino example.

Or we’ve been a tad more old school and used the classic 555 to do it. Or maybe like me, you went through a phase of hacking together Phase Shift and other oscillators because well… it’s fun!

But [Junichi AKITA] has more extreme tastes, deciding that a custom IC layout is the way to go. [Junichi] designed a ring oscillator composed of flip-flops, then hand laid out each MOSFET placing each layer exactly where it should be fabricated.

The resulting design was then fabricated by an academic shuttle service in Japan (a bit like the well known MOSIS service). The result is a tiny circuit in the top right corner of the IC. Which of course [Junichi] then had to wirebond (check the video for a cool 1980s style Westbond machine which are still hugely popular in Japan).

IC Layout… by hand!

Optical image of the fabricated circuit.

[Junichi] bonded the die directly to a PCB (COB). I assume, purely for irony, a 555, and ATtiny based oscillator were also laid out on the board.

I guess you might have a couple of lingering questions. First you’ll likely bemoan your lack of your own fabrication facility (I’m still eyeing those used 1 micron fab lines that crop up on eBay from time to time). And secondly you might be asking yourself… why?

Both these questions are somewhat answers by the MakeLSI project. This growing project in Japan seems to have opened up semiconductor fabrication to all kinds of projects.

While my Japanese isn’t good enough to fully understand what’s happening it’s clear there are many awesome projects going on. Including joys such as IC layouts designed in vector graphics packages (Inkscape) and die images packed with interesting layouts, anime characters and QR codes.

For more awesome images and information (unfortunately all in Japanese) you can check them out on Facebook or on their homepage.

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Measuring capacitance with wax dielectric

How To Measure The Dielectric Constant For DIY Capacitors

October 12, 2016 by Steven Dufresne 7 Comments

Every now and then you need to make your own capacitor. That includes choosing a dielectric for it, the insulating material that goes between the plates. One dielectric material that I use a lot is paraffin wax which can be found in art stores and is normally used for making candles. Another is resin, the easiest to find being automotive resin used for automotive body repairs.

The problem is that you sometimes need to do the calculations for the capacitor dimensions ahead of time, rather than just throwing something together. And that means you need to know the dielectric constant of the dielectric material. That’s something that the manufacturer of the paraffin wax that makes it for art stores won’t know, nor will the manufacturers of automotive body repair resin. The intended customers just don’t care.

It’s therefore left up to you to measure the dielectric constant yourself, and here I’ll talk about the method I use for doing that.

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