An ASCII Terminal Like It’s 1974

August 21, 2022 by 10 Comments

It’s quite probable that any of you who have built a keyboard will have done so using a matrix of keys connected to a microcontroller, or if you are old-school, a microprocessor. A CPU can scan the keyboard matrix with ease, and pass whatever is typed either to whatever software it is running, or to a host computer. There was a time however when available CPUs were not considered powerful enough to do all this and also perform a useful task, so a keyboard would have its own decoder chip that would output ASCII over a parallel interface. It’s an era [John Calhoun] harks back to with Adam74, a little ASCII terminal which takes its input from that 7-bit parallel port.

In the place of a forest of TTL chips which might have graced the originals, within that attractive curved laser cut acrylic case is an LCD display and a Teensy microcontroller board. There’s a level shifter for the classic 5 volt logic, and of course a small buzzer for the essential BEL character. In these days when a parallel interface is relatively rare, he describes the rediscovery of alternate earth lines in a ribbon cable to minimize cross-talk. Should you wish to try your own, everything can be found on GitHub.

All in all it’s a fun way to rediscover an old idea.

Should’ve Used A 555 — Or 276 Of Them

August 10, 2022 by 33 Comments

When asked to whip up a simple egg timer, most of us could probably come up with a quick design based on the ubiquitous 555 timer. Add a couple of passives around the little eight-pin DIP, put an LED on it to show when time runs out, and maybe even add a pot for variable timing intervals if we’re feeling fancy. Heck, many of us could do it from memory.

So why exactly did [Jesse Farrell] manage to do essentially the same thing using a whopping 276 555s? Easy — because why not? Originally started as an entry in the latest iteration of our 555 Contest, [Jesse]’s goal was simple — build a functional timer with a digital display using nothing but 555s and the necessary passives. He ended up needing a few transistors and diodes to pull it off, but that’s a minor concession when you consider how many chips he replaced with 555s, including counters, decoders, multiplexers, and display drivers. All these chips were built up from basic logic gates, a latch, and a flip-flop, all made from one or more 555s, or variants like the 556 or 558.

As one can imagine, 276 chips take a lot of real estate, and it took eleven PCBs to complete the timer. A main board acts as the timer’s control panel as well as serving as a motherboard for ten other cards, each devoted to a different block of functions. It’s all neat and tidy, and very well-executed, which is in keeping with the excellent documentation [Jesse] produced. The whole thing is wonderfully, needlessly complex, and we couldn’t be more tickled to feature it.

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Hackaday Links: August 7, 2022

August 7, 2022 by 10 Comments

If you ever needed proof that class-action lawsuits are a good deal only for the lawyers, look no further than the news that Tim Hortons will settle a data-tracking suit with a doughnut and a coffee. For those of you who are not in Canada or Canada-adjacent, “Timmy’s” is a chain of restaurants that are kind of the love child of a McDonald’s and a Dunkin Donut shop. An investigation into the chain’s app a couple of years ago revealed that customer location data was being logged silently, even when they were not using the app, and even far, far away from the nearest Tim Hortons. The chain is proposing to settle with class members to the tune of a coupon good for one free hot beverage and one baked good, in total valuing a whopping $8.68. The lawyers, on the other hand, will be pulling in $1.5 million plus taxes. There’s no word if they are taking that in cash or as 172,811 coffees and doughnuts, but we think we can guess.

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Laptoppin’ Like 1975

August 6, 2022 by 22 Comments

When we first saw the PZ1 laptop — a 6502 laptop-style computer with a small display and 512K of RAM — we couldn’t help but think of the old AIM 65 computer from Rockwell, although that only had 1K of memory. The other thing the AIM didn’t have was an ancillary microcontroller to help out that is way more powerful than the main processor.

There are actually several versions of the PZ1 and you can find some very detailed information over on Hackaday.io and GitHub. Recently, [Adam] release version 2.0 and tested some PC boards that are working well.

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Hackaday Podcast 179: Danger Chess, Corona Motors, An Omni-Walker, And A Fast Talking Telescope

July 29, 2022 by 3 Comments

Join Hackaday Editor-in-Chief Elliot Williams and Staff Writer Dan Maloney for their take on the hottest hacks in a hot, hot week. We found a bunch of unusual mechanisms this week, like an omnidirectional robot that’s not quite wheeled but not quite a walker either. Or, if you’d rather fly, there’s a UAV that’s basically a flying propeller. There’s danger afoot too, with news of a chess-playing robot with a nasty streak, a laser engraver that’ll probably blind you, and a high-voltage corona motor that actually does useful work. We’ll use our X-ray vision to take a deep dive into a 60-GHz phased array antenna, let a baby teach a machine what it means to be hungry, and build a couple of toy cameras just for funsies. Balloons as a UI? Maybe someday, thanks to ultrasonic levitation. And we’ll wrap things up by snooping in on the Webb telescope’s communications, as we find out how many people it takes to make wire harnesses. Spoiler alert: it’s a lot.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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You Can Build A Giant 7-Segment Display Of Your Very Own

July 27, 2022 by 7 Comments

Sometimes you need to display a number nice and large, making it easily readable at a good distance. [Lewis] has just the thing for that: a big expandable 7-segment display.

The build is modular, allowing it to be extended from 2 to 10 digits and beyond. The digits themselves are made of 3D-printed parts assembled onto acrylic. These can then be ganged up in a wooden frame for displaying larger numbers with more digits. Individual elements are lit by addressable LEDs, and the project can be built using an Arduino Nano or an ESP8266 for control. The latter opens up possibilities for controlling the screen over WiFi, which could prove useful.

[Lewis] has built his own version for a local swim club, where it will be used as a laptimer. Other applications could be as a scoreboard in various sports, or to confuse your neighbours by displaying random numbers in your front yard.

We’ve seen a similar build from [Ivan Miranda] that served well as a workshop clock, too. Video after the break.

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A ’70s TV With ’20s Parts

July 24, 2022 by 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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