classic hacks

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Restoring A Japanese Oscilloscope

May 2, 2017 by 5 Comments

Oscilloscopes have come a long way. Today’s scope is more likely to look like a tablet than an old tube-based instrument. Still, there’s something about looking into a glowing green tube, especially if you’ve done the work to resurrect that old hollow state device. [NFM] picked up a Kikusui OP-31C–a vintage Japanese scope at a second-hand store. He made a video of his restoration efforts that you can see below.

The scope actually powered up and worked the first time. Of course, unlike a modern scope, the OP-31C has to warm up before it will show up. However, the pots needed cleaning and as a precaution, he replaced the old oil and electrolytic capacitors.

The big transformer and the coarse-looking single sided circuit board certainly will bring back memories if you are old enough. [NFM] had a schematic of the scope and takes you on a tour of the innards, although his schematic had some subtle differences from the actual unit, possibly due to some repair work.

He was going to rebuild one of the large electrolytic “can” capacitors to keep the outer shell with newer (and smaller) modern capacitors. However, he found a very similar modern capacitor and used that, instead.

We think it would have been more fun if the scope didn’t work. However, it was still a great tear down of the old tube-based device. This is a bigger device than the last old scope tear down we looked at. Not that we haven’t seen smaller ones (although, the link in the post has moved).

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The Raspberry Pi Becomes A SCSI Device

May 1, 2017 by 90 Comments

SCSI devices were found in hundreds of different models of computers from the 80s, from SUN boxes to cute little Macs. These hard drives and CDROMs are slowly dying, and with that goes an entire generation of technology down the drain. Currently, the best method of preserving these computers with SCSI drives is the SCSI2SD device designed by [Michael McMaster]. While this device does exactly what it says it’ll do — turn an SD card into a drive on a SCSI chain — it’s fairly expensive at $70.

[GIMONS] has a better, cheaper solution. It’s a SCSI device emulator for the Raspberry Pi (original link dead, here’s the new location of this writeup). It turns a Raspberry Pi into a SCSI hard drive, magneto-optical drive, CDROM, or an Ethernet adapter using only some glue logic and a bit of code.

As far as the hardware goes, this is a pretty simple build. The 40-pin GPIO connector on the Pi is attached to the 50-pin SCSI connector through a few 74LS641 transceivers with a few resistor packs for pullups and pulldowns. The software allows for virtual disk devices – either a hard drive, magneto-optical drive, or a CDROM – to be presented from the Raspberry Pi. There’s also the option of putting Ethernet on the SCSI chain, a helpful addition since Ethernet to SCSI conversion devices are usually rare and expensive.

Officially, [GIMONS] built this SCSI hard drive emulator for the x68000 computer, developed by Sharp in the late 80s. While these are popular machines for retrocomputing aficionados in Japan, they’re exceptionally rare elsewhere — although [Dave Jones] got his mitts on one for a teardown. SCSI was extraordinarily popular for computers from the 70s through the 90s, though, and since SCSI was a standard this build should work with all of them.

If your retrocomputer doesn’t need a SCSI drive, and you’re feeling left out of the drive-emulation club, the good news is there’s a Raspberry Pi solution for that, too: this Hackaday Prize entry turns a Pi into an IDE hard drive.

Thanks [Gokhan] for the tip!

Little EBay Tesla Coil Gets An Upgrade

April 30, 2017 by 14 Comments

Like so many of the projects we feature, this one started with a cheap eBay module purchase. In this case, it was a little Tesla coil that made decent sized arcs but wasn’t quite good enough. The result was a super-sized solid state Tesla coil with better results and room to grow.

As [GreatScott!] discovered, the little eBay Tesla coil has a pretty neat design. The exciter is a Slayer circuit, a super simple one-transistor design. His reverse engineering revealed that the primary coil is simply a loop trace on the PCB under the secondary coil. Sadly, his attempt to replace the primary and reproduce the Slayer exciter resulted in anemic performance. What’s a hacker to do in that case except build a bigger coil? Much bigger — like “build your own winding jig” bigger. Twelve hundred secondary turns and an appropriately menacing-looking primary later, the results were — still anemic. It turns out the Slayer is just not up to the task. He turned to an inverter circuit that was previously used in a wireless energy transfer circuit, and we finally get to see a little of the Tesla coil magic. But wait! There’s more to come, as future videos will tweak the circuit and optimize the coil for better performance.

It’s no surprise that Tesla coils are a popular project around here, especially the musical kinds, from the tiny to the large. Music doesn’t seem to be on [GreatScott!]’s mind, though, and we’ll be watching with interest to see where he takes this build.

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TI 99/4A Weather Station

April 30, 2017 by 21 Comments

If you still have a drawer full of slap bracelets from the 1990s because, you know, they might come back, then you’ll appreciate [Vorticon’s] latest project. Sure, we see lots of weather stations, but this one is controlled by a TI 99/4A computer. This home computer from the 1980s was actually ahead of its time with a 16-bit processor.

The sensors use Xbee modules and an Arduino Uno. Of course, the Uno has more power than the TI computer, but that’s not really the point, right? He’s made a series of videos detailing the construction (you can see the first one below, but there are five, so far).

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Cheap And Easy Emergency Butane Stove

April 27, 2017 by 25 Comments

Homemade stoves are a very popular hack, you can find a zillion videos on YouTube, mostly on alcohol stoves, and they work great. Less common are butane fueled stoves, but [Thomas Kim] has uploaded a video on a super easy and cheap butane stove.

Like many other DIY stoves, the body is a soda aluminum can. After sealing the top side with aluminum foil, you just need to drill some holes in it. Other necessary components are a metal tube and a syringe needle that acts as flow regulator. [Thomas Kim] makes an interesting fixture that is attached to the can and lets you control the pressure on the can valve and adjust the flame of the stove via a couple of screws.

The stove works great. It is a nice and simple project if you want to start experimenting with these stoves. Safety is important of course, working ventilated area and protect the butane source from heat (in this case the feed tube keeps it away from the burner). Some other projects you may find interesting are this easy rocket stove, or  even this project to make your own briquettes from waste materials. Enjoy and stay safe.

A Modern Day PDP-11 Front End

April 26, 2017 by 26 Comments

Hands up if you feel your spiritual home is in front of a terminal with a “DIGITAL” logo on it.  It’s a name that has long ago been subsumed into first Compaq and then by extension HP, but it’s one with a lot of history when it comes to computing.

From the start of the electronic computing age, there were the computers we’d probably now describe as mainframes. Big computers that cost the GDP of a small country, filled an entire floor of a building, and could only be found in government departments, universities, and large companies. By the 1960s, the technologies existed to build computers that broke this mould, could be bought within the budget of a smaller organisation, and for which you didn’t need a huge air-conditioned basement to house. These so-called minicomputers were the great revolution of that era because they bought the fruits of computing into everyday business, and probably the most successful of the companies that produced them was the Maynard, Massachusetts-based Digital Equipment Corporation, or DEC.

DEC produced a succession of minicomputers in their PDP line, of which the most successful was their PDP-11 series. These were 16-bit minicomputers that remained in their product line from their launch in 1970 through to the early 1990s, and were available in a succession of configurations and physical form factors. The famous view of a PDP-11 is of a set of floor-to-ceiling racks, but there were also standalone terminal models, and desktop models. One of these, a PDP-11/03 from 1975, has come into the hands of [Joerg], and he’s used it to craft his LSIbox, the PDP11/03 card frame packaged with a BeagleBone for access via a modern-day interface. It’s a build in the vein of modern tube audio amplifiers that feature the retro hardware on the top of their cases, the card frame is exposed as a feature on top of a white case that is featureless except for a genuine PDP-11/03 front panel.

You might ask why anyone would do this in order to run PDP-11 software when the BeagleBone could almost certainly emulate the vintage hardware much faster than the real thing. But to take that view is to miss the point; the PDP-11 series are a seminal part of computing history, and to have genuine PDP-11 hardware on your desk is quite an achievement.

We’ve shown you a few PDP-11 projects in the past. There was this minimalist PDP-11 implementation using one of the later integrated PDP-11 processors, and we’ve seen a faithful reproduction of an earlier PDP-11 front panel powered by a Raspberry Pi.

Replicating A Victorian Era Console

April 26, 2017 by 27 Comments

[Dt99jay] lives in a historic Victorian-era district in the UK.  Most homes in the area have ornate exterior window dressings with stone consoles holding up heavy stone hood molding.

The window hood molding turned out to be wood — most likely the result of damage repaired after the blitzkrieg bombings of WWII. The 1940’s era work is now rotting away, so it was time for a repair. When the hood was pulled away from the window, disaster struck. One console completely crumbled, while the other lost large chunks of material. The They weren’t solid stone after all, but replacements most likely molded with Coade stone.

There are no ready replacements for consoles like this. [dt99jay] couldn’t just swap them out for modern looking replacements, so he set about replicating the consoles. The remaining console was much too delicate to remove from the building, so [dt99jay] glued the missing pieces back on. He then filled any missing parts and carefully scraped way all the loose paint. Then came the difficult part — making a mold while the console was still mounted on the house.

Room Temperature Vulcanizing (RTV) silicone rubber was carefully applied to the console. The RTV is thick enough to stay on while it dries. After several thick layers of RTV, the console was covered. [Dt99jay] then covered the mold with plaster of Paris bandages to support it. The finished mold was carefully removed from the house, and [dt99jay] filled all the low spots and air bubbles with RTV.

New castings were made using a mixture of cement and playground sand. Once painted, the results matched perfectly. The historic conservation committee was pleased, and the window was once again structurally sound.