We often think that if a piece of software had the level of documentation you usually see for hardware, you wouldn’t think much of it. Sure, there are exceptions. Some hardware is beautifully documented, and poorly documented software is everywhere. [Graham Sutherland’s] been reviewing schematics and put together some notes on what makes a clean schematic.
Like coding standards, some of these are a bit subjective, but we thought it was all good advice. Of course, we’ve also violated some of them when we are in a hurry to get to a simulation.
Around the globe, some classrooms are using fancy digital handheld devices to let people answer questions. One such example of this hardware is the Smart Response PE. These devices are largely useless outside the classroom, so [Ray Burne] decided to hack one for our 2025 One Hertz Challenge.
The Smart Response PE device is similar in shape and size to an old-school candybar cellphone. It runs on a Texas Instruments CC2533 microcontroller, which drives a simple black-and-white LCD. User interface is via a numeric keypad and a few extra control buttons on the front panel. Thanks to Github user [serisman], there are readily available development tools for this hardware. [Ray] notes it provides a straightforward Arduino-like programming experience.
[Ray] decided to modify the hardware to act as a stopwatch. But not just one stopwatch—ten stopwatches at once! Pressing a number from 0 to 9 will activate that given timer, and it will start ticking up on the LCD screen. One can pause the screen updates to get a temporary laptime reading by pressing the enter key. Meanwhile, pressing the Home button will reset the screen and all timers at once. [Ray] also explains on the project page how to add a real power switch to the device, and how to modify the programming pins for easy access.
It’s a fun build, and one that could prove useful if you regularly find yourself having to time ten of something at once. Maybe eggs? In any case, it’s certainly easier than juggling ten separate stopwatches at once! Meanwhile, if you’re hacking your own obscure hardware finds, don’t hesitate to notify the tipsline!
With the assistance of an extra pair of hands, but without any power tools in sight, this old master marks up a piece of wood and then cuts a collapsible chair out of it. He uses various types of saw, chisels, a manual drill, and various other hand tools. His workspace is a humble plank with a large clamp attached. At the end he does use a powered hot air gun to heat the finish he uses to coat the final product.
How fast does your heart beat? It’s a tough question to answer, because our heart rate changes all the time depending on what we’re doing and how our body is behaving. However, [Ludwin] noted that resting heart rates often settle somewhere near 60 bpm on average. Thus, they entered a heart rate sensor to our 2025 One Hertz Challenge!
The build is based around a Wemos D1 mini, a ESP8266 development board. It’s hooked up to a MAX30102 heart beat sensor, which uses pulse oximetry to determine heart rate with a photosensor and LEDs. Basically, it’s possible to determine the oxygenation of blood by measuring its absorbance of red and infrared wavelengths, usually done by passing light through a finger. Meanwhile, by measuring the change in absorption of light in the finger as blood flows with the beat of the heat, it’s also possible to measure a person’s pulse rate.
The Wemos D1 takes the reading from the MAX30102, and displays it on a small OLED display. It reports heart rate in both beats per minute and in Hertz. if you can happen to get your heartrate to exactly 60 beats per minute, it will be beating at precisely 1 Hertz. Perhaps, then, it’s the person using Ludwin’s build that is actually eligible for the One Hertz Challenge, since they’re the one doing something once per second?
In any case, it shows just how easy it is to pick up biometric data these days. You only need a capable microcontroller and some off-the-shelf sensors, and you’re up and running.
Rubber! It starts out as a goopy material harvested from special trees, and is then processed into a resilient, flexible material used for innumerable important purposes. In the vast majority of applications, rubber is prized for its elasticity, which eventually goes away with repeated stress cycles, exposure to heat, and time. When a rubber part starts to show cracks, it’s generally time to replace it.
Researchers at Harvard have now found a way to potentially increase rubber’s ability to withstand cracking. The paper, published in Nature Sustainability, outlines how the material can be treated to provide far greater durability and toughness.
This week, Hackaday’s Elliot Williams and Kristina Panos met up over the tubes to bring you the latest news, mystery sound, and of course, a big bunch of hacks from the previous week.
In Hackaday news, get your Supercon 2025 tickets while they’re hot! Also, the One Hertz Challenge ticks on, but time is running out. You have until Tuesday, August 19th to show us what you’ve got, so head over to Hackaday.IO and get started now. Finally, its the end of eternal September as AOL discontinues dial-up service after all these years.
On What’s That Sound, Kristina got sort of close, but this is neither horseshoes nor hand grenades. Can you get it? If so, you could win a limited edition Hackaday Podcast t-shirt!
After that, it’s on to the hacks and such, beginning with a talking robot that uses typewriter tech to move its mouth. We take a look at hacking printed circuit boards to create casing and instrument panels for a PDP-1 replica. Then we explore a fluid simulation business card, witness a caliper shootout, and marvel at one file in six formats. Finally, it’s a telephone twofer as we discuss the non-hack-ability of the average smart phone, and learn about what was arguably the first podcast.
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!
Download in DRM-free MP3 and savor at your leisure.
Despite the regularly proclaimed death of physical media, new audio albums are still being published on CD and vinyl. There’s something particularly interesting about Lorde’s new album Virgin however — the CD is a completely clear disc. Unfortunately there have been many reports of folks struggling to get the unique disc to actually play, and some sharp-eyed commentators have noted that the CD doesn’t claim to be Red Book compliant by the absence of the Compact CD logo.
The clear Lorde audio CD in all its clear glory. (Credit: Adrian’s Digital Basement, YouTube)
To see what CD players see, [Adrian] of Adrian’s Digital Basement got out some tools and multiple CD players to dig into the issue. These players range from a 2003 Samsung, a 1987 NEC, and a cheap portable Coby player. But as all audio CDs are supposed to adhere to the Red Book standard, a 2025 CD should play just as happily on a 1980s CD player as vice versa.
The first step in testing was to identify the laser pickup (RF) signal test point on the PCB of each respective player. With this hooked up to a capable oscilloscope, you can begin to see the eye pattern forming. In addition to being useful with tuning the CD player, it’s also an indication of the signal quality that the rest of the CD player has to work with. Incidentally, this is also a factor when it comes to CD-R compatibility.
While the NEC player was happy with regular and CD-R discs, its laser pickup failed to get any solid signal off the clear Lorde disc. With the much newer Samsung player (see top image), the clear CD does play, but as the oscilloscope shot shows, it only barely gets a usable signal from the pickup. Likewise, the very generic Coby player also plays the audio CD, which indicates that any somewhat modern CD player with its generally much stronger laser and automatic gain control ought to be able to play it.
That said, it seems that very little of the laser’s light actually makes it back to the pickup’s sensor, which means that along with the gain the laser output gets probably cranked up to 11, and with that its remaining lifespan will be significantly shortened. Ergo it’s probably best to just burn that CD-R copy of the album and listen to that instead.
