Velocity Based Training, With A Camera

March 8, 2020 by Jenny List 3 Comments

In the world of weight training, the buzzword of the moment is VBT, or Velocity Based Training. This involves sensors being used to measure the speed and position of a weight as it moves through each repetition, and thus provide instant feedback for the athlete and glean information from which they can work upon their training routine. Typically the sensors involved may be accelerometers, but [Kris] has taken a different tack using a webcam and machine vision to do the same job.

The barbell has a green disc attached to its end, and the software tracks it and measures the velocity. It issues a warning when the velocity of a repetition drops below a preset level, telling the athlete to stop their set before pushing themselves too far. Under the hood is a Python script and OpenCV, and the write-up in his GitHub repository takes us through its camera calibration to remove the effects of distortion, and set-up. All calibration of distances within the image is made through the known size of the green disc, allowing the software to accurately chart the distance through which it travels.

We’ve not seen a machine vision approach to weight training before, but we have seen one using accelerometers. Maybe this project will re-ignite interest in this field.

Smashed Laptop Becomes Stylish All-In-One

March 8, 2020 by Lewin Day 15 Comments

Many of us will have broken a laptop at one point or another, destroying the screen or smashing the case. It can be frustrating, as there’s a perfectly usable computer in there, trapped inside a broken husk of a body. [Matthew] saw this not as a problem, but an opportunity – and built a beautiful all-in-one desktop PC. (Video, embedded below.)

With a badly damaged Thinkpad laptop to hand, an ASUS monitor was sourced with a thin body and flat back, perfect for mounting hardware. An MDF base was created, on to which the laptop motherboard was mounted. A USB hub and audio amplifier were then added, along with a USB power isolator and soundcard to avoid problems with groundloops from the onboard headphone output. Speakers were Harman Kardon units salvaged from an old television, providing great quality sound for the build.

There’s plenty of great ideas in the video, from using epoxy for a strong permanent assembly, to a nifty hack to make the power button work. It has us contemplating a build for our own broken laptops in the junkpile. We’ve seen other creative all-in-one builds too, like this one inside a printer.

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Z80 Computer Is Both Arduino And Shield

March 7, 2020 by Erin Pinheiro 7 Comments

There have been plenty of Z80 computer builds here on Hackaday, but what sets them apart is what you do with them. [Andrew] writes in with his Z80 single-board computer made from scratch, using the Arduino standard headers for its I/O. In turn, since he needed an easy way to program the flash memory which holds the software to run on the Z80, he used an Arduino Mega as a debugger, making the SBC an Arduino shield itself.

Using such a common header pinout for the Z80 computer allows it to be used with a variety of readily-available Arduino shields. This compatibility is achieved with an analog-digital converter and a 3.3 V regulator, mimicking the pins found in an Arduino Uno. The code, available on GitHub, includes an extensive explanation and walkthrough over the process in which the Mega takes over the bus from the Z80 to function as a fully-featured debugger. Programs can be loaded through embedding an assembly listing into the Mega’s sketch, or, once the debugger is up you can also upload a compiled hex file through the serial connection.

This isn’t the first time [Andrew] has been featured here, and his past projects are just as interesting. If you need to translate a Soviet-era calculator’s buttons into English, hack a metallurgical microscope or even investigate what’s that Clacking Clanking Scraping Sound, he’s the one you should call.

If Coffee == True {

March 7, 2020 by Bryan Cockfield 14 Comments

Having a shared coffee maker in the workplace is both a blessing and a curse. It’s nice to have constant access to coffee, but it can be frustrating to find the coffee pot emptied right as you walk in to the break room. To solve this problem in their office, [Vitort] and co. built an IOT solution that notifies everyone of the current coffee status on a Slack channel.

This project wasn’t built just as a convenience for the office, either. It makes extensive use of AWS SNS, the simple notification system from Amazon Web Services because they wanted to learn to use this technology specifically. Besides the notification system, the device itself is based on a NodeMCU/ESP8266, communicating over WiFi, and is a simple push-button design which coffee drinkers push when a fresh pot is made, and then push again when the coffee is empty.

While relatively straightforward, this project is a good one to look at if you’ve been interested in AWS at all, especially the simple notification system. It’s a pretty versatile tool, and all of the code used in the project is available on the project page for your reading pleasure. If you’re more interested in the coffee aspect of this project, we have a special coffee maker for you too.

That Retro Video Look, Without The Tapes

March 7, 2020 by Jenny List 11 Comments

We’re lucky to live in an age of rapid technological advancement, lucky in more ways than one because as well as receiving a constant supply of new things, we have the benefit of the older tech that once we lusted over, at knock-down prices. [Luke Baker] spent his youth as a skateboarder, and the cameras of desire in that community were the high-end MiniDV models. They may not have high definition but their output has a Millennial aesthetic that captures the period, so he’s brought one into the 2020s by adding a digital SD card recorder designed for a multirotor to it.

On the face of it this is a pretty straightforward job of coupling an off-the-shelf recorder to a battery and the camera’s analogue output terminals. But the resulting spaghetti on what is supposed to be a portable device is hardly attractive, so he’s created an all-in-one 3D-printed enclosure that is attached to the camera’s handle with a set of cable ties. It’s shaped to fit the recorder and has a sliding lid over the battery compartment, and he’s added a handy on-off switch. Whether or not he takes it to the skate park in a bid to roll back the decades, as you can see int he video below the break it’s a well-executed piece of work that should serve to remind that there’s still life in some of this easily-available old tech if you’re prepared for a bit of lateral thinking.

This isn’t the first vintage video hack we’ve seen, back in 2016 we were treated to the grainy period feel of a vintage 8mm camera through the eye of a Raspberry Pi.

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An 8085 Retrocomputer From The Heart

March 7, 2020 by Jenny List 22 Comments

The world of 8-bit retrocomputing splits easily into tribes classified by their choice of processor. There are 6809 enthusiasts, 6502 diehards, and Z80 lovers, each sharing a bond to their particular platform that often threads back through time to whatever was the first microcomputer they worked with. Here it’s the Z80 as found in the Sinclair ZX81, but for you it might be the 6502 from an Apple ][. For [Craig Andrews] it’s the 8085, and after many years away from the processor he’s finally been able to return to it and recreate his first ever design using it. The SBC-85 is not wire-wrapped as the original was, instead he’s well on the way to creating an entire ecosystem based around an edge-connector backplane.

The CPU board is an entire computer in its own right as can be seen in the video below the break, and pairs the 8085 with 8k of RAM, a couple of 2732 4k EPROMs, and an 8155 interface chip. This last component is especially versatile, providing an address latch, timer, I/O ports, and even an extra 256 bytes of RAM. Finally there is some glue logic and a MAX232 level shifter for a serial port, with no UART needed since the 8085 has one built-in. The minimal computer capable with this board can thus be slimmed down significantly, something that competing processors of the mid 1970s often struggled with.

Craig’s web site is shaping up to be a fascinating resource for 8085 enthusiasts, and so far the system sports that backplane and a bus monitor card. We don’t see much of the 8085 here at Hackaday, perhaps because it wasn’t the driver for any of the popular 8-bit home computers. But it’s an architecture that many readers will find familiar due to its 8080 heritage, and could certainly be found in many control applications before the widespread adoption of dedicated microcontrollers. It would be interesting to see where Craig takes this next, with more cards, and perhaps making a rival to the RC2014 over in Z80 country.

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A Calculator In 2020?

March 7, 2020 by Elliot Williams 91 Comments

This week, Al Williams wrote up an article on what might be the last scientific calculator. Back in the day, the fanciest of scientific calculators had not just sin, cos, and tan, but were also programmable so that you could code in frequently used formulae. And the calculator that he reviews is certainly powerful: with a screen, processor, and memory almost rivalling a mid-scale smartphone.

Wait a minute! “Almost”? I have a smartphone in my pocket right now. Why would I want something less powerful, when all that the calculator brings to the table is a bit of software? And that app can even be purchased for $20!

I’ll confess. I want a proper desktop calculator from time to time. But why? Sure, I can run calculations on the very computer that I’m using to type right now. And in terms of programming languages, the resources are far superior on my laptop. Unit conversions? Units, or the Interwebs. Heck, I can even type calculations directly into the Unix world’s default editor.

But there’s something nice about the single-purpose device. Maybe it’s the feel of the keys. Maybe it’s because it doesn’t require a context-switch on the computer. Maybe it’s irrational calculator nostalgia. Or maybe it’s an elegant tool from a more civilized age: the user experience is better because the tool is just simpler.

I like stand-alone devices that do their one thing right, and I almost always pick them over their more complex, if also more capable, counterparts when I only need that function. The fixed wrench over the adjustable wrench. The standalone audio recorder over my computer’s software. The simple bench power supply over the programmable. And, when I’m actually setting out to take good photos, a real camera instead of my cell phone’s. Purpose-built tools tend to work much better for their purpose than devices that try to do everything.

The days of the standalone calculator are nearly gone, though, so what am I going to do? I’m certainly not going to shell out megabucks for an overly-fancy calculator, nor am I going to be lured by nostalgia into picking up an antique at the ridiculous prices they fetch online. That leaves one option, and it’s both the Hackaday and the Jedi way. I’m going to have to build it myself. Where am I going to get a nice-feeling numeric keypad?