Hackaday Podcast 239: Overclocking, Oscilloscopes, And Oh No! SMD Out Of Stock!

Elliot Williams and Al Williams got together again to discuss the best of Hackaday for a week, and you’re invited. This week, the guys were into the Raspberry Pi 5, CNC soldering, signal processing, and plasma cutting. There are dangerous power supplies and a custom 11-bit CPU.

Of course, there are a few Halloween projects that would fit in perfectly with the upcoming Halloween contest (the deadline is the end of this month; you still have time). OpenSCAD is about to get a lot faster, and a $20 oscilloscope might not be a toy after all. They wrap up by talking about Tom Nardi’s latest hardware conversion of DIP parts to SMD and how TVs were made behind the Iron Curtain.

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Overclocking Raspberry Pi 5’s SoC To 3 GHz And 1 GHz GPU

Overclocking computer systems is a fun way to extract some free performance, or at least see how far you can push the hardware before you run into practical limitations. The newly released Raspberry Pi 5 with BCM2712 SoC is no exception here, with Tom’s Hardware having a go at seeing how far both the CPU and GPU in the SoC can be pushed. The BCM2712’s quad Cortex-A76 CPU is normally clocked at 2.4 GHz and the VideoCore VII GPU at 800 MHz. By modifying some settings in the /boot/config.txt configuration file these values can be adjusted.

In order to verify that an overclock was stable, the Stressberry application was used, which fully loads the CPU cores. Here something like a combination of stress-ng and glxgears could also be used, to stress both the CPU and GPU. With the official actively cooled heatsink the CPU reached a temperature of 74°C with a whole board power usage of about 10 Watts. At idle this dropped to 3 Watts at 46°C. At these speeds, the multiple Raspberry Pi 5 units OCed by Tom’s Hardware were mostly stable, though one of the team’s boards experienced a few crashes. This suggests that this level of OCing could still be subject to luck of the draw, and long-term stability would have to be investigated as well.

As for the practical use cases of OCing your Raspberry Pi 5, benchmarks showed a marked uplift in compression and Sysbench benchmark scores, but OCing the GPU had no real positive impact on YouTube or 3D performance, leading even to a massive increase in dropped frames with video playback. This probably means that increasing the CPU clock may be beneficial, but OCing the GPU could be futile without also OCing the RAM frequency, if at all possible.

Realistically, the Raspberry Pi SoCs never were speed monsters, with even the Raspberry Pi 4B’s SoC being beaten handily in 2020 by a budget dual-core Intel CPU.  The current Intel Alder-Lake-N-based N100 SoC has a 6 Watt TDP and boosts up to 3.4 GHz while its Xe-LP-based iGPU (with AV1 decoding support) makes for a decent gaming experience within a ~16 Watt power envelope. Clearly, any OCing of the Raspberry Pi boards is more for the challenge of it, but then so is running the latest Intel CPU at 10 GHz with liquid nitrogen cooling.

A wooden digital clock with a metal knob on one end

Hackaday Prize 2023: Stretch Your Day With This 29-Hour Clock

Modern life can be stressful. Many of us struggle to balance work, family, exercise, and an ever-growing list of hacking projects, all of which claim our attention during the day. If you sometimes feel that those 24 hours just don’t cut it, you might be in luck: [HIGEDARUMA] has built a clock that can stretch your day by up to five hours.

Sadly, [HIGEDARUMA] hasn’t invented time travel (yet). What his clock does instead is slow down its own pace in the evening to push back the midnight hour. When it finally does reach 12:00 a.m., the clock’s pace is accelerated to ensure it’s back in sync with the rest of the world by six in the morning. It might seem silly, but there is a certain logic to it: [HIGEDARUMA] explains that evenings felt much longer when he was a child and that he would like to try and experience that again. Our sense of time may change over our lifetime, even if the actual passage of time doesn’t.

Timescales aside, the 29-hour clock is a neat piece of work from a hardware point of view. The case is made from 4 mm laser-cut MDF with wood-grain foil on the outside. Inside, there’s an ESP32 to run the show, along with an RTC module and three four-digit seven-segment LED displays. A chunky “volume” knob on the front lets you choose how much you’d like your day to be stretched.

We’ve seen clocks with non-linear dials before, as well as extremely linear ones, but this might be the first one with a non-constant pace. It makes us wonder what the passage of time feels like for those frozen in ice for 46,000 years.

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Clock Hack Gives DEC Rainbow A New Lease On Life

In retrocomputing circles, it’s often the case that the weirder and rarer the machine, the more likely it is to attract attention. And machines don’t get much weirder than the DEC Rainbow 100-B, sporting as it does both Z80 and 8088 microprocessors and usable as either a VT100 terminal or as a PC with either CP/M or MS-DOS. But hey — at least it got the plain beige box look right.

Weird or not, all computers have at least a few things in common, a fact which helped [Dr. Joshua Reichard] home in on the problem with a Rainbow that was dead on arrival. After a full recapping — a prudent move given the four decades since the machine was manufactured — the machine failed to show any signs of life. The usual low-hanging diagnostic fruit didn’t provide much help, as both the Z80 and 8088 CPUs seemed to be fine. It was then that [Joshua] decided to look at the heartbeat of the machine — the 24-ish MHz clock shared between the two processors — and found that it was flatlined.

Unwilling to wait for a replacement, [Joshua] cobbled together a temporary clock from an Arduino Uno and an Si5351 clock generator. He connected the output of the card to the main board, whipped up a little code to generate the right frequency, and the nearly departed machine sprang back to life. [Dr. Reichard] characterizes this as a “defibrillation” of the Rainbow, and while one hates to argue with a doctor — OK, that’s a lie; we push back on doctors all the time — we’d say the closer medical analogy is that of fitting a temporary pacemaker while waiting for a suitable donor for a transplant.

This is the second recent appearance of the Rainbow on these pages — [David] over at Usagi Electric has been working on the graphics on his Rainbow lately.

Turning Soviet Electronics Into A Nixie Tube Clock

Sometimes you find something that looks really cool but doesn’t work, but that’s an opportunity to give it a new life. That was the case when [Davis DeWitt] got his hands on a weird Soviet-era box with four original Nixie tubes inside. He tears the unit down, shows off the engineering that went into it and explains what it took to give the unit a new life as a clock.

Each digit is housed inside a pluggable unit. If a digit failed, a technician could simply swap it out.

A lot can happen over decades of neglect. That was clear when [Davis] discovered every single bolt had seized in place and had to be carefully drilled out. But Nixie tubes don’t really go bad, so he was hopeful that the process would pay off.

The unit is a modular display of some kind, clearly meant to plug into a larger assembly. Inside the unit, each digit is housed in its own modular plug with a single Nixie tube at the front, a small neon bulb for a decimal point, and a bunch of internal electronics. Bringing up the rear is a card edge connector.

Continues after the break…

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Turning A Quartz Clock Module Into A Time Reference

If you’re looking for a 1-second time reference, you’d probably just grab a GPS module off the shelf and use the 1PPS output. As demonstrated by [InazumaDenki], though, an old quartz clock module can also do the job with just a little work.

The module was harvested from an old Seiko wall clock, and features the familiar 32.768 KHz crystal you’d expect. This frequency readily divides down by 2 multiple times until you get a useful 1 Hz output. The module, originally designed to run a clock movement, can be repurposed with some basic analog electronics to output a useful time reference. [InazumaDenki] explains various ways this can be done, before demonstrating his favored method by building the device and demonstrating it with a decade counter.

It has some benefits over a GPS time reference, such as running at a much lower voltage and needing no external signal inputs. However, it’s also not going to be quite as accurate. Whether that matters to you or not depends on your specific application. Video after the break.

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Clock Escapement Uses Rolling Balls

The escapement mechanism has been widely used for centuries in mechanical clocks. It is the mechanism by which a clock controls the release of stored energy, allowing it to advance in small, precise intervals. Not all mechanical clocks contain escapements, but it is the most common method for performing this function, usually hidden away in the clock’s internals. To some clockmakers, this is a shame, as the escapement can be an elegant and mesmerizing piece of machinery, so [Brett] brought his rolling ball escapement to the exterior of this custom clock.

The clock functions as a kitchen timer, adjustable in 10-second increments and with several preset times available. The rolling ball takes about five seconds to traverse a slightly inclined, windy path near the base of the clock, and when it reaches one side, the clock inverts the path, and the ball rolls back to its starting place in another five seconds. The original designs for this type of escapement use a weight and string similar to a traditional escapement in a normal clock. However, [Brett] has replaced that with an Arduino-controlled stepper motor. A numerical display at the bottom of the clock and a sound module that plays an alert after the timer expires rounds out the build.

The creation of various types of escapements has fascinated clockmakers for centuries, and with modern technology such as 3D printers and microcontrollers, we get even more off-the-wall designs for this foundational piece of technology like [Brett]’s rolling ball escapement (which can also be seen at this Instructable) or even this traditional escapement that was built using all 3D-printed parts.

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