Day: May 16, 2016

Raspberry Pis Sweeten A Library’s Bottom Line

May 16, 2016 by 37 Comments

Here’s a great real-world use case for the Pi—a small job for a small computer. [viking–] works in a public library. Like many public libraries, this one has catalog-only terminals that are separate from the computers you reserve to get your fix of cat videos and Bejeweled Blitz. The catalog computers needed to be upgraded, and [viking–] replaced them all with Raspis.

They’re all running Raspbian and boot directly into Chromium with a clean profile every time. The Pis are otherwise completely locked down and accessible only through SSH. A dedicated WiFi network and whitelisted web access help keep them secure. The Pis reboot after five minutes of inactivity which erases all login credentials and bookmarks.

These terminals are scattered throughout the library. Those closest to the front desk have their Pi in a VESA mount on the back of the monitor. The others are locked up in cabinets so they don’t get pinched by the patrons. Library budgets are lean enough already. [viking–] was able to get management sign-off for the project by building a single prototype to show the simplicity of the system and the projected cost savings. Thanks to a couple of cron jobs, the Pis shut the monitors down every night, saving hundreds of dollars per year.

Meet Up With Hackaday This Saturday In San Mateo

May 16, 2016 by 5 Comments

We’ll be at Bay Area Maker Faire and we want to have a beer with you on Saturday night.

Two years ago we headed off to the Bay Area Maker Faire and thought we’d invite friends and acquaintances to congregate at a bar on Saturday night. Anyone who’s been to the Faire (or been through a harrowing weekend of working a booth) knows that a bar stool and frothy beverage are a great way to recuperate. The turnout was amazing, we easily filled up O’Neill’s Irish Pub with that first meetup, and the Hackaday BAMF Meetup was born. Last year we packed it to the seams. This year we’re planning for an even bigger turnout that will go late into the evening.

I’ve only ever heard one complaint about this event; the band is too loud. This year O’Neill’s doesn’t have a band lined up so everything seems to be coming up roses. Come hang out with us! If you RSVP we’ll buy your first beer. Bring your stories, your easily transported hacks to show off, and have fun with the eclectic and enthralling community that turns out for this, the greatest meetup on earth.

Hackaday Letter from the Editors

If this is the first you’ve heard about this year’s meetup, you should subscribe to our weekly newsletter. Every week, a Hackaday Editor writes about what’s been going on that week, and shares a few of the most interesting posts from the past seven days. You can sign up for it in the sidebar to the right or with that signup link I just shared. If you’d like to know what you’re getting yourself into, here’s the most recent newsletter which we sent out on Friday. It’s a mini Hackaday delivered to your mailbox.

Why Kickstarter Products Fail

May 16, 2016 by 68 Comments

It seems every week we report on Kickstarter campaigns that fail in extraordinary fashion. And yet there are templates for their failure; stories that are told and retold. These stereotypical faceplants can be avoided. And they are of course not limited to Kickstarter, but apply to all Crowd Funding platforms. Let me list the many failure modes of crowdfunding a product. Learn from these tropes and maybe we can break out of this cycle of despair.

Failure Out of the Gate

You don’t hear about these failures, and that’s the point. These are crowd funded projects that launch into the abyss and don’t get any wings through printed word or exposure. They may have a stellar product, an impressive engineering team, and a 100% likelihood of being able to deliver, but the project doesn’t get noticed and it dies. Coolest Cooler, the project that raised $13 million, failed miserably the first time they ran a campaign. It was the second attempt that got traction.

The solution is to have a mailing list of interested people are ready to purchase the moment you launch, and share to everyone they know. Reach out to blogs and news organizations a month early with a press package and a pitch catered to their specific audience. Press releases get tossed. Have a good reason why this thing is relevant to their audience. Offer an exclusive to a big news site that is your target market.

Continue reading “Why Kickstarter Products Fail” →

A Dis-Integrated 6502

May 16, 2016 by 57 Comments

The 6502 is the classic CPU. This chip is found in the original Apple, Apple II, PET, Commodore 64, BBC Micro, Atari 2600, and 800, the original Nintendo Entertainment System, Tamagotchis, and Bender Bending Rodriguez. This was the chip that started the microcomputer revolution, and holds a special place in the heart of every nerd and technophile. The 6502 is also possibly the most studied processor, with die shots of polysilicon and metal found in VLSI textbooks and numerous simulators available online.

The only thing we haven’t seen, until now, is a version of the 6502 built out of discrete transistors. That’s what [Eric Schlaepfer] has been working on over the past year. It’s huge – 12 inches by 15 inches – has over four thousand individual components, and so far, this thing works. It’s not completely tested, but the preliminary results look good.

The MOnSter 6502 began as a thought experiment between [Eric] and [Windell Oskay], the guy behind Evil Mad Scientist and creator of the discrete 555 and dis-integrated 741 kits. After realizing that a few thousand transistors could fit on a single panel, [Eric] grabbed the netlist of the 6502 from Visual6502.org. With the help of several scripts, and placing 4,304 components into a board design, the 6502 was made dis-integrated. If you’re building a CPU made out of discrete components, it only makes sense to add a bunch of LEDs, so [Eric] threw a few of these on the data and address lines.

This is the NMOS version of the 6502, not the later, improved CMOS version. As such, this version of the 6502 doesn’t have all the instructions some programs would expect. The NMOS version is slower, more prone to noise, and is not a static CPU.

So far, the CPU is not completely tested and [eric] doesn’t expect it to run faster than a few hundred kilohertz, anyway. That means this gigantic CPU can’t be dropped into an Apple II or commodore; these computers need a CPU to run at a specific speed. It will, however, work in a custom development board.

Will the gigantic 6502 ever be for sale? That’s undetermined, but given the interest this project will receive it’s a foregone conclusion.

Correction: [Eric] designed the 555 and 741 kits

Making A Fixed Voltage Power Supply Adjustable

May 16, 2016 by 33 Comments

Switch-mode power supplies are ubiquitous. Standard off-the-shelf modules in a consistent range of form factors available from multiple manufacturers. Globalized manufacturing and trade has turned them from expensive devices into commodity parts, and they long ago replaced iron-cored transformers as the go-to choice when a high-current low-voltage mains supply is required.

[Lindsay Wilson] faced a power supply problem for a motor he was working with, it required 7.4V and no off-the-shelf power supplies were to be found with that voltage. His solution was to take a 12V supply and modify it to deliver a variable voltage so he could dial in his requirement. A Chinese-made 12v 33A switch-mode supply was purchased, and he set to work.

In the event he was able to design a replacement feedback divider incorporating a rotary potentiometer, and achieve a voltage range of 5 to 15V. A small LED voltmeter mounted next to it in the PSU case gave him a very neat result.

Modifying a switch-mode supply to deliver a different voltage is a well-worn path we’ve covered at least once before. What makes Lindsay’s article worth a read is his reverse-engineering and examination in detail of the PSU circuit. If you’d like to learn more about all the different facets of design that go into a switch-mode PSU, it’s a detailed yet readable primer. We’d suggest reading our recent series on mains and high voltage safety before cracking open a switch-mode PSU yourself, but even if you’re never going to do it there’s something to be gained from knowing in detail how they work.

We’ve featured [Lindsay]’s work here at Hackaday a few times over the years. Check out his ultrasonic transducer power supply, which might be of use were you were building the ultrasonic soldering iron we featured not long ago, his laser stripping of ribbon cables, and his tale of decapping a USB isolator chip.