Building A Tube-Based Stereo Amp, In Classic Style

July 31, 2022 by Donald Papp 34 Comments

It’s not every day we see the results of someone putting their own spin on a vintage tube amp, but that’s exactly what [lens42] did in creating the McIntosh 217, created as a “mini” version of the McIntosh MC275, a classic piece of audio equipment. Both are pictured next to each other, above.

When it comes to vintage hi-fi stereo amplifiers, two units had particular meaning for [lens42]: the McIntosh MC275 Power Amp, and the Dynaco ST35. The Dynaco was a more budget-friendly amplifier, but looked like a plain box. The McIntosh, however, proudly showed off its tubes and transformers in all their glory. The “McIntosh 217” is design-wise basically a smaller McIntosh MC275, with the innards of a Dynaco ST35.

With so much needing to be designed from the ground up, CAD was invaluable. Component layout, enclosure design, and even wiring and labeling all had to be nailed down as much as possible before so much as heating up the soldering iron. Even so, there were a few hiccups; a vendor had incorrect measurements for a tube socket which meant that the part would not fit. A workaround involved modifying the holes and as luck would have it, the change wasn’t an eyesore. Still, [lens42] reminds us all that whenever you can, have the required parts in-hand for confirmation of dimensions before sending CAD files off for cutting or fabrication.

Many of us can relate to the fact that the whole project was a labor of love and made no real financial sense, but the end result is fantastic, and creating such a thing is something all of us — not just chasers of that elusive “tube sound” — can appreciate.

Foam Cutter Moves Like A Hot Knife Through Butter

July 28, 2022 by Kristina Panos 13 Comments

Make enough attempts to cut foam using whatever you’ve got — utility knife, hacksaw, serrated plastic knife — and you’ll wish hard for something that cuts cleaner, faster, and better. While there are all sorts of ways to build a hot wire foam cutter, this design from [jasonwinfieldnz] is both interesting and imitable.

If you don’t already know it, nichrome wire is nifty stuff that’s readily available in thrift store hair dryers and toasters. It stretches as it heats up, and shrinks as it cools back down.

The interesting part of this build is that instead of using a spring to keep tension on the nichrome wire, [jasonwinfieldnz] designed and 3D-printed a bow out of PLA that does the job elegantly. While [jason] was initially concerned that the bow might possibly melt, he found in practice that although the bow does get warm to the touch, it’s nowhere near hot enough to even warp.

One nice touch is the simple fence that rides along two slots and secures with wingnuts. We also like that [jason] made this foam cutter largely from scrap material, and rather than buy a spool of nichrome, he opted for a skinny heating element and pillaging the wire.

If you’re a nichrome noob, know that it doesn’t take much juice to do the job. Even though a computer power supply is what [jason] had lying around, it’s complete overkill, so you would definitely want to limit the current. Check out the build video after the break.

Still not portable enough for you? All you really need is a 18650, some nichrome, and a few bits and bobs to hold it all together.

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Hackaday Prize 2022: Digital Dice Towers Built In Beautiful Retro Cases

July 26, 2022 by Lewin Day 5 Comments

Retro hardware often looks fantastic, but we may find we no longer need it for its original function. [John Anderson] found that to be the case with some old Heathkit gear, and set about giving them a fun overhaul.

With the help of AVR microcontrollers, the devices have been repurposed into electronic dice towers for playing Dungeons & Dragons. A seed is generated based on the chip’s uptime, and supplied to a pseudorandom number generator that emulates dice rolls. The devices can be configured to roll a variety of dice, including the usual 6, 8, 10, and 20-sided varieties. Plus, they can be set to roll multiple dice at a time — useful when you’re rolling complicated spells and attacks in combat.

[John] has converted a variety of Heathkit devices, from Morse code trainers to digital multi-meters. They provide their beautiful cases and a great retro aesthetic, and we think they’d make fitting table decoration for retro cyberpunk tabletop games, too.

Creating your own electronic dice is a great way to get familiar with programming microcontrollers. Video after the break.

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Protecting The Hughes H4 Hercules With… Beach Balls?

July 26, 2022 by Ryan Flowers 45 Comments

While visiting the Evergreen Aviation & Space Museum in McMinnville, OR, USA over the weekend, I came across a hack.

In addition to the excellent displays on site and an area where one can watch a video on repeat, the museum offers guided tours for a very reasonable price. And it was during this tour that my life as an aviation geek changed forever. Why? I got to visit the flight deck of the H4 and even sit in the pilots seat where Howard Hughes sat when he flew the plane almost 75 years ago.

It was later in the tour, after I’d had a moment to take in the enormity of sitting in the seat, that I found a wonderful hack to share with you all: and it’s all about beach balls. Continue reading “Protecting The Hughes H4 Hercules With… Beach Balls?” →

A ’70s TV With ’20s Parts

July 24, 2022 by Bryan Cockfield 45 Comments

Keeping older technology working becomes exponentially difficult with age. Most of us have experienced capacitor plague, disintegrating wire insulation, planned obsolescence, or even the original company failing and not offering parts or service anymore. To keep an antique running often requires plenty of spare parts, or in the case of [Aaron]’s vintage ’70s Sony television set, plenty of modern technology made to look like it belongs in a machine from half a century ago.

The original flyback transformer on this TV was the original cause for the failure of this machine, and getting a new one would require essentially destroying a working set, so this was a perfect candidate for a resto-mod without upsetting any purists. To start, [Aaron] ordered a LCD with controls (and a remote) that would nearly fit the existing bezel, and then set about integrating the modern controls with the old analog dials on the TV. This meant using plenty of rotary encoders and programming a microcontroller to do the translating.

There are plenty of other fine details in this build, including audio integration, adding modern video and audio inputs like HDMI, and adding LEDs to backlight the original (and now working) UHF and VHF channel indicators. In his ’70s-themed display wall, this TV set looks perfectly natural. If your own display wall spotlights an even older era, take a look at some restorations of old radios instead.

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Condemned Precision Capacitors Find New Home, Refuse To Become Refuse

July 24, 2022 by Ryan Flowers 12 Comments

Ah, the age old tradition of Dumpster diving! Sometimes we happen to spot something that’s not quite trash, but not quite perfect, either. And when [dzseki], an EEVblog.com forum user, spotted some high-precision capacitors being 86’d at their employer’s e-waste pile, [dzseki] did what any good hacker would do: took them home, tested them, and tore them down to understand and either repair or reuse them. They explain their escapades and teardown in this EEVblog.com forum post.

High-precision capacitors with RF connectors.

If you’re not familiar with capacitors, they are really just two or more plates of metal that are separated by an insulator, and in the case of these very large capacitors, that insulator is mostly air. Aluminum plates are attached with standard bolts, and plastic insulators are used as needed. There’s also discussion of an special alloy called Invar that lends to the thermal stability of the capacitors.

[dzseki] notes that these capacitors were on their way to the round file because they were out of spec, but only by a very, very small amount. They may not be usable for the precision devices they were originally in, but it’s clear that they are still quite useful otherwise. [dzseki]

Of course, Dumpster diving for cool parts is nothing new, and we’ve covered nifty projects such as this frankenmonitor bashed together from two bin finds.

Thank you [David] for the great tip, and don’t forget to leave your own in the Tip Line.

A Home Made Sewing Machine May Be The Only One

July 17, 2022 by Jenny List 37 Comments

The sewing machine is a tool that many of us will have somewhere around our workshop. Concealed within it lies an intricate and fascinating mechanism. Some of us may have peered inside, but very few indeed of us will have gone to the effort of building our own. In case you had ever wondered whether it was possible, [Fraens] has done just that, with what he claims may be the only entirely homemade sewing machine on the Internet.

If you’ve ever studied the history of sewing machines you’ll notice that it bears a striking resemblance to some of the earliest commercial machines, with a relatively short reach and an entirely open construction. The main chassis appears to be laser-cut acrylic while all the fittings are 3D-printed, with machined brass bushes and aluminum rods for the other metal parts. The design utilizes a hand crank, but is also pictured with a DC motor. It makes for a fascinating illustration of how sewing machines work. Sadly we can’t see any design file links (Update: He’s contacted us to tell us they’re now on Thingiverse.), so you might have to be inventive if that’s the way you want to build your own. Take a look at it in the video below the break.

Fancy a sewing machine but don’t fancy making your own? We’ve got the guide for that, and for filling the rest of your textile bench.

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