classic hacks

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An Amiga 600 With An FPGA Inside

July 10, 2018 by 24 Comments

The Amiga is the platform that refuses to die. It must be more than two decades since the debacle surrounding the demise of the original hardware, yet the operating system is still receiving periodic updates, you can still buy Amiga hardware now sporting considerably more powerful silicon than the originals, and its worldwide community is as active as ever.

One of those community projects is the MiSTer FPGA Amiga-on-an-FPGA, and it was this that caught the attention of [Mattsoft]. Impressed with the quality of its recreation of an Amiga, he decided to turn his into a “real” Amiga, so found an Amiga 600 case and keyboard, and set to work. Into the mix went the Terasic DE10-Nano FPGA board, I/O and RAM boards, a Tynemouth Software keyboard interface, a USB hub, and some well-designed 3D-printed parts allow the original Amiga case to be used without modifications.

The Amiga 600 was the base model in the final Amiga range from the early 1990s, and at the time despite its HDD interface and PCMCIA slot it languished in the shadow of its Amiga 1200 sibling. The styling has aged well though, and this upgrade certainly breathes a little life back into the case if not strictly the machine itself. If you want to learn a bit more about MiSTer then a look at the project’s wiki is in order. Perhaps you don’t have an Amiga though and would like to wallow in a bit of nostalgia without splashing out for hardware, in that case, give AROS a look.

Thanks [intric8] for the tip.

Vintage eight transistor stereo amplifier

Eight Transistor Stereo Amplifier From The Days Of Yore

July 9, 2018 by 31 Comments

Reading an article about the first transistorized Hi-Fi amplifier, [Netzener] got the itch to make one. But what to use for the starting point? Enter an old Radio Shack P-Box stereo amplifier kit. After a few modernizations and tweaks, the result is an 8-transistor stereo amplifier that’s aesthetically pleasing, sounds great, and is fully documented.

The Radio Shack kit used germanium transistors, but with their high leakage current and low thermal conductivity, he decided to convert it to work with silicon transistors. He also made some improvements to the push-pull bias circuit and limited the high-frequency response. As for the finished product, in true [Netzener] style, he assembled it all to look like the original completed Radio Shack amplifier. He even wrote up a manual which you’d think, as we did at first, was the original one, giving that old, comfortable feeling of reading quality Radio Shack documentation.

Check out the video below where he uses a 9 V battery and half a watt per channel to fill a room with clear, stereo sound.

This isn’t the first Radio Shack kit that [Netzener] has adapted. Check out his single tube radio and classic neon “Goofy Light” box.

Continue reading “Eight Transistor Stereo Amplifier From The Days Of Yore” →

Rocket Bullets: The Flame And Fizzle Of The Gyrojet

July 9, 2018 by 45 Comments

In the 1950’s and 60’s, the world had rocket fever. Humankind was taking its first steps into space and had sights on the moon. Kids could build rockets at the kitchen table and launch them in the schoolyard. On the darker side, the arms race was well underway with the US and USSR trying to close the fictional missile gap.

All around the world, engineers were trying to do new things with rockets. Among these were Robert Mainhardt and Arthur T. Biehl, who thought rockets could be useful as small arms. Together they formed MBA (short for Mainhardt and Biehl Associates), with an eye toward future weapons – – specifically rocket bullets.

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Pinball Wizard Hacks Table For Tommy Stage Show

July 7, 2018 by 9 Comments

Ever since he was a young hacker
[Mark Gibson] has messed with the silver ball.
From Soho down to Denver
he must have fixed them all.
But we ain’t seen anything like this
in any amusement hall.
That darn devious hacker
sure hacks a mean pinball.

He hacks it like an expert,
Becomes part of the machine
Automating all the bumpers
Always wiring clean
His table plays by automation,
And radio control for all
That darn devious hacker
sure hacks a mean pinball.

Continue reading “Pinball Wizard Hacks Table For Tommy Stage Show” →

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.

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Build Your Own Rowing Machine, Now With Digital Readout!

July 4, 2018 by 12 Comments

An ergometer is a fancy fitness word for a rowing machine, a device which can be used to work out the muscles used in rowing. It’s an excellent cardio workout that can also build upper body strength, and resistance can be varied depending on the individual’s fitness goals. But perhaps you need to measure your workout to see your progress – in which case, [Dave]’s instrumentation package might be right up your alley.

The basic mechanical build involves a wooden frame, fitted with a rowing setup built around a modified bicycle wheel. The wheel has vanes attached, made of what appears to be cut sections of PVC pipe. These act essentially as dampers, using the air to create the resistance for the rower to work against.

The wheel is instrumented with a chopper wheel and an IR optical switch, which measures the rotational speed of the wheel during rowing. This signal is fed into an ATMega328 which runs the calculations on the rower’s performance. It’s all fed to a Nokia 5110 screen for display, which makes a lovely throwback for those that remember the brick fondly.

[Dave] touches not only on the electronic aspects of the build, but also does an excellent job of breaking down the mathematics behind rowing performance. It’s a great resource that builds on top of the excellent work by the OpenErgo project.

If we’ve whet your thirst for exercise machine hacks, you’d better check out this treadmill to belt grinder mod.

Furniture And Motors Make A Strange Bedfellow

July 1, 2018 by 15 Comments

Beds! They don’t move around enough, so the young people say. They need more motors, more horsepower, more self-driving smarts – right? Honestly, we’re not sure, but if that’s the question being asked, [randofo] has the answer.

Aptly named, Bedfellow is an art project that sought to create a bed that could explore and socialise with occupants aboard. The core principle was not just to create a bed that could move under its own power, but one that could intelligently drive around and avoid obstacles, too. This is achieved through the use of ultrasonic sensors, with an Arduino Mega as the brains. The bed chooses a random direction in which to move, checking for obstacles on the way. It’s pretty basic as far as “self-driving” technology goes, but it gets the job done.

Far from being a lightweight artistic statement, the bed has some serious performance credentials. The drivetrain is a couple of 4 horsepower DC motors with speed controllers cribbed from a golf cart. These are fed through a 20:1 gear reduction to boost torque and avoid the bed moving too quickly. [Randofo] reports it can comfortably haul 12 people without slowing down, and we don’t doubt it. With that much power, your average flatback bed would be ripped to pieces, but never fear for this one – there’s plenty of heavy engineering holding it together.

It’s refreshing to see an art project executed with both elegant aesthetics and brutally powerful hardware. Sure, it might not be much good for sleeping unless you live in a loft with a concrete floor, but hey – they’re awfully popular these days. Now all it needs are some ground effects.