No Active Components In This Mysterious Audio Oscillator

What’s the simplest audio frequency oscillator you can imagine? There’s the 555, of course, and we can think of a few designs using just two transistors or even a few with just one. But how about an oscillator with no active components? Now there’s a neat trick.

Replicating [Stelian]’s “simplest audio oscillator on the Internet” might take some doing on your part, since it relies on finding an old telephone. Like, really old — you’ll need one with the carbon granule cartridge in the handset, along with the speaker. Other than that, all you’ll need is a couple of 1.5-volt batteries, wiring everything in one big series loop, and placing the microphone and speaker right on top of each other. Apply power and you’re off to the races. [Stelian]’s specific setup yielded a 2.4-kHz tone that could be altered a bit by repositioning the speaker relative to the mic. On the oscilloscope, the waveform is a pretty heavily distorted sine wave.

It’s a bit of a mystery to [Stelian] as to how this works without something to provide at least a little gain. Perhaps the enclosure of the speaker or the mic has a paraboloid shape that amplifies the sound just enough to kick things off? Bah, who knows? Let the hand-waving begin!

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New JEDEC DDR5 Memory Specification: Up To 8800 MT/s, Anti-Rowhammer Features

Rapid row activations (yellow rows) may change the values of bits stored in victim row (purple row).
Row hammer” by DsimicOwn work. Licensed under CC BY-SA 4.0 via Wikimedia Commons.

As DDR SDRAM increases in density and speed, so too do new challenges and opportunities appear. In the recent DDR5 update by JEDEC – as reported by Anandtech – we see not only a big speed increase from the previous maximum of 6800 Mbps to 8800 Mbps, but also the deprecation of Partial Array Self Refresh (PASR) due to security concerns, and the introduction of Per-Row Activation Counting (PRAC), which should help with row hammer-related (security) implications.

Increasing transfer speeds is primarily a matter of timings within the limits set by the overall design of DDR5, while the changes to features like PASR and PRAC are more fundamental. PASR is mostly a power-saving feature, but can apparently be abused for nefarious means, which is why it’s now gone. As for PRAC, this directly addresses the issue of row hammer attacks. Back in the 2014-era of DDR3, row hammer was mostly regarded as a way to corrupt data in RAM, but later it was found to be also a way to compromise security and effect exploits like privilege escalation.

The way PRAC seeks to prevent this is by keeping track of how often a row is being accessed, with a certain limit after which neighboring memory cells get a chance to recover from the bleed-over that is at the core of row hammer attacks. All of which means that theoretically new DDR5 RAM and memory controllers should be even faster and more secure, which is good news all around.

FLOSS Weekly Episode 780: Zoneminder — Better Call Randal

This week Jonathan Bennett and Aaron Newcomb chat with Isaac Connor about Zoneminder! That’s the project that’s working to store and deliver all the bits from security cameras — but the CCTV world has changed a lot since Zoneminder first started, over 20 years ago. The project is working hard to keep up, with machine learning object detection, WebRTC, and more. Isaac talks a bit about developer burnout, and a case or two over the years where an aggressive contributor seems suspicious in retrospect. And when is the next stable version of Zoneminder coming out, anyway?

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80s Function Generator Is Both Beauty And Beast

You know how the saying goes — they don’t make them like this anymore. It’s arguably true of pretty much any electronic device given the way technology changes over time, though whether or not it’s objectively a bad thing is going to vary from case to case.

As a practical example, take a look at the insides of this 80’s vintage HP 3314A function generator shared on the EEV Blog Forum by [D Straney].

Hinged PCBs allow for easy access

With multiple PCBs stacked on top of each other, it’s hard to imagine that more components could possibly be crammed into it. One board in particular appears to be an entire Motorola 6800 computer, something which today would likely be replaced with a single microcontroller.

Which is actually why [D Straney] shared this with us in the first place. After seeing our recent post about a modern waveform generator that’s basically an empty box thanks to its modern components, they thought this would be a nice example of the opposite extreme.

So, is it a good or a bad thing that test equipment isn’t made this way anymore? Well, it’s hard to argue with the improved capabilities, smaller footprint, and reduced cost of most modern gear. But damn is the inside of this HP 3314A gorgeous. As one of the commenters on the page put it, hardware from this era was really a work of art.

Amazon Ends California Drone Deliveries While Expanding To Arizona

The outgoing MK27 drone used by Amazon today for deliveries. (Credit: Amazon)
The outgoing MK27 drone used by Amazon today for deliveries. (Credit: Amazon)

When Amazon started its Prime Air drone delivery service in 2022, it had picked College Station (Texas) and Lockeford (California) as its the first areas where the service would be offered. Two years later, Amazon has now announced that it will be expanding to the West Valley of the Phoenix Metro area in Arizona from a new Tolleson center, while casually mentioning buried in the press release that the Lockeford area will no longer be serviced. No reason for this closure was provided, but as a quite experimental service drastic shifts can be expected as Amazon figures out what does and does not work.

Amazon Prime Air features custom drones that can transport packages up to 5 lbs (~2.27 kg) to its destination within an hour, if the item is listed as Prime Air capable for your area. Along with the change in service areas, Amazon is also testing its new MK30 drone (pictured, top), which should be much quieter due to a new propeller design and have twice the range of the old MK27 as well.

Even if flying drone delivery isn’t quite a blow-away success yet, Amazon doesn’t seem to be letting up on investing in it, and it could be argued that for certain items like medication or perishables, it does make a certain sense over traditional delivery and pick-up methods.

An Elbow Joint That Can

We’re not certain whether [Paul Gould]’s kid’s prosthetic elbow joint is intended for use by a real kid or is part of a robotics project — but it caught our eye for the way it packs the guts of a beefy-looking motorized joint into such a small space.

At its heart is a cycloidal gearbox, in which the three small shafts which drive the center gear are driven by a toothed belt. The motive power comes from a brushless motor, which is what gives the build that impressive small size. He’s posted a YouTube short showing its internals and it doing a small amount of weight lifting, so it evidently has some pulling power.

If you’re interested in working with this design, it can be downloaded for 3D printing from Thingiverse. We think it could find an application in plenty of other projects, and we’d be interested to see what people do with it. There’s certainly a comparison to be maid over robotic joints which use wires for actuation.

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Programming Ada: First Steps On The Desktop

Who doesn’t want to use a programming language that is designed to be reliable, straightforward to learn and also happens to be certified for everything from avionics to rockets and ICBMs? Despite Ada’s strong roots and impressive legacy, it has the reputation among the average hobbyist of being ‘complicated’ and ‘obscure’, yet this couldn’t be further from the truth, as previously explained. In fact, anyone who has some or even no programming experience can learn Ada, as the very premise of Ada is that it removes complexity and ambiguity from programming.

In this first part of a series, we will be looking at getting up and running with a basic desktop development environment on Windows and Linux, and run through some Ada code that gets one familiarized with the syntax and basic principles of the Ada syntax. As for the used Ada version, we will be targeting Ada 2012, as the newer Ada 2022 standard was only just approved in 2023 and doesn’t change anything significant for our purposes.

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