The 7805 Is Dead! Long Live The 7805!

September 5, 2022 by 70 Comments

The 78XX series of regulators are very handy to use. If you need, say, a 5V regulator, you grab a 7805, add a capacitor for stability, and send in enough voltage for the regulator to work with. Cheap and easy. However, the part is not without its faults.

A stock 7805 can’t convert 5.1V to 5V. You need to have a good bit more voltage coming in. But the more voltage you put in, the more the part is going to dump out as heat. So running from 9V is going to be cooler than running from 24V. All that heat isn’t very energy efficient on batteries, either. [Stefan] wanted to do better, so he made a drop-in replacement for these venerable regulators some time ago. But he’s recently made the board layouts available so you can build your own replacement, too.

The device accepts 4.5 to 16V, and you can select the output voltage using two resistors. You can draw up to 2A out of the regulator, which is more than you can say for a stock 7805.

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Custom Calculator Brings Us Back To The 70s

September 1, 2022 by 7 Comments

There are certain design aesthetics from every era that manage to survive the fads of their time and live throughout history. Ancient Greek architecture is still drawn upon for design inspiration in modern buildings, the mid-century modern style from the 60s still inspires various designs of consumer goods, and the rounded, clean looking cars from the 90s are still highly desirable qualities in automotive design. For electronics, though, we like this 70s-inspired calculator that [Aaron] recently built.

The calculator hearkens back to the days of calculators like the HP-29C with its large buttons and dot-matrix display. [Aaron] built the case out of various woods with a screen angled towards the user, and it uses a LCD display similar to those found in antique calculators. The brain of the calculator is an Arduino which fits easily into the case, and [Aaron] also built the keyboard from scratch with Cherry MX-style mechanical keys soldered together into a custom shape.

The software to run the calculator is fairly straightforward, but we are most impressed with the woodworking, styling, and keyboard design in this build. [Aaron] is also still ironing out some bugs with the power supply as it uses a DC-DC converter to power the device from a single lithium battery. For those who are more fond of early 2000s graphing calculators instead, be sure to take a look at this graphing calculator arcade cabinet.

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YouTube Like It’s 1970s France With This Minitel-VCR Mashup

August 27, 2022 by 10 Comments

When it’s not just sticking fake gears on things and calling it a day, the Steampunk look is pretty cool. Imagining technology in a world stuck with Victorian aesthetics is a neat idea, and one that translates to the look of other time periods — Fallout, anyone?

But what if you try to create a technological aesthetic based on a more recent and less celebrated time? That’s what [ghettobastler] has attempted with this somewhat bizarre Minitel-YouTube-VCR mash-up. Taking inspiration from a webcomic’s take on “Formicapunk,” modern tech based on the aesthetic of the wildly successful French videotex service of the 70s and 80s, the system uses a very cool Minitel 1B terminal and a Raspberry Pi 3.

A custom level-shifter for the Pi

With the help of a level-shifting circuit, the Mintel and the Pi talk over serial, allowing the terminal to be used as, well, a terminal for the Pi. Videos are downloaded from YouTube by the Pi, which sends the video to the VCR from its composite output, and controls the VCR with an IR LED that emulates the original remote. Come to think of it, just watch the video below — it’s probably easier than trying to describe it.

It’s weird, true, but we love the look of that Minitel terminal. Something about it just screams cyberdeck; if anyone has a spare one of these, get busy and put something together for our Cyberdeck Design Contest.

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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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