Hackaday Podcast Ep14: Keeping Raspberry’s SD Card Alive, We Love MRRF, And How Hot Are Flip Chips?

Elliot Williams and Mike Szczys take a look at advances in photogrammetry (building 3D models out of many photographs from a regular camera), a delay pedal that’s both aesthetically and aurally pleasing, and the power of AI to identify garden slugs. Mike interviews Scotty Allen while walking the streets and stores of the Shenzhen Electronics markets. We delve into SD card problems with Raspberry Pi, putting industrial controls on your desk, building a Geiger counter for WiFi, and the sad truth about metal 3D printing.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

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An Even Smaller World’s Smallest LED Blinky

Everything can be done with a 555. It’s a universal law, as all readers know. And a flashing light, you might think, will have been done before many times. But nobody has ever created a 555 flashing light as small as thie one created by [TWires], who has taken a TI LMC555 chip-scale packaged 555 and dead-bugged a working flasher on its surface using 01005 discrete components. There is a video showing it in operation that we’ve placed below the break, and it’s tiny. We probably all consider ourselves to be quite good at soldering, but this piece of work is in another class entirely.

The project was inspired by [Mike Harrison]’s previous holder of the smallest blinky prize, which used a PIC microcontroller atop a tiny surface mount supercapacitor. It uses the same capacitor for power, but we’d say it’s taken the blinky to new levels of tininess. Does this mean a new arms race is upon us in the world of tiny blinkies? We hope so, and though it’s difficult to imagine they can get much smaller we can’t wait to see what people come up with. If there’s one thing about our community it’s that saying something can’t be done is unwise: one of you will find a way if it is at all possible. Even Microchip’s MIC1555 might be a bit big though, so something inventive is called for.

For a fascinating run-down of the state of the 555 art, read this article from our own [Ted Yapo].

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Fizzle Loop Synth Does It With 555 Timers

For every project that uses an Arduino to make soup or an ESP8266 to hash bitcoin, there’s always someone out there uttering the same old refrain. I could have done it with a 555. More often than not, this is true, even if it is tangential to the discussion being had. In this case however, such a statement is moot. [lonesoulsurfer] has built the Fizzle Loop Synth, featuring not one, but three triple-nickel timers.

It’s a build that delights in both presentation and performance. The hardware is elegantly slotted into a vintage metal flashlight case, which is absolutely covered in controls. It’s an aesthetic that gives us an irresistible urge to start twiddling knobs and flicking switches. Inside, two 555s are set up as basic flasher circuits, each feeding a vactrol – essentially a resistive optoisolater. Inside is an LED, which is optically coupled to a light-dependent resistor. The LEDs are flashed by the 555s, and this creates a varying resistance which is used to feed a third 555 which generates the tones.

The final result is a fun little noisebox that’s capable of generating quite the variety of bleeps, bloops and blops. There’s an onboard speaker for noodling on the go, as well as a line-out if you need to record your work on external hardware. It would be great fun to hear this circuit hooked up to a modular synth, too.

For a history lesson on the venerable 555, we’ve got you covered. Video after the break.

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The Three Faces Of The 555

In these days of cheap microcontrollers, it is hard to remember there was a time when timing things took real circuitry. Even today, for some applications it is hard to beat the ubiquitous 555 timer IC. It is cheap, plentiful, and reliable. What’s interesting about the 555 is it isn’t so much a dedicated chip as a bunch of building blocks on a chip. You can wire those building blocks up in different ways to get different effects, and [learnelectronics] has a video showing the three major modes you typically see with the 555: astable, bistable, and monostable.

The 555 is really only a few comparators, a voltage divider, one or two transistors, a flip flop and an inverter. The idea is you use a capacitor to charge and the comparators can set or reset the flip flop in different ways. A reset input or the flip flop can turn on the transistor to discharge the capacitor.

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Making The World’s Fastest 555 Timer, Or Using A Modern IC Version

If you’re not familiar with the 555 timer, suffice it to say that this versatile integrated circuit is probably the most successful ever designed, and has been used in countless designs, many of which fall very far afield from the original intent. From its introduction, the legendary 555 has found favor both with professional designers and hobbyists, and continues to be used in designs from both camps. New versions of the IC are still being cranked out, and discrete versions are built for fun, a temptation I just couldn’t resist after starting this article.

If you think all 555s are the same, think again. Today, a number of manufacturers continue to produce the 555 in the original bipolar formulation as well as lower-power CMOS. While the metal can version is no longer available, the DIP-8 is still around, as are new surface-mount packages all the way down to the chip-scale. Some vendors have also started making simplified variants to reduce the pinout. Finally, you can assemble your own version from a few parts if you need something the commercial offerings won’t do, or just want a fun weekend project. In my case, I came up with what is probably the fastest 555-alike around, although I spared little expense in doing so.

Follow along for a tour of the current state of the 555, and maybe get inspired to design something entirely new with this most versatile of parts.

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Love Inspires CD Player Hack

The heart is an impressive piece of hardware. It’s a rare pump that runs continuously for over 80 years in some cases. It’s also, for some reason or other, become a common human symbol of love and affection. In this vein, [Deepak Khatri] has built a beating electronic heart out of basic, readily available components.

The heart of the build (pun intended) is a lens assembly salvaged from a CD player, which uses a coil and permanent magnet to move the lens in order to read across a disc. In this case, the coil is instead fed pulses from an astable multivibrator circuit built with a hacker favourite, the 555 timer IC. It’s all assembled on a breadboard, which is a great way to build such projects that rely on experimentation through the swapping of component values.

The end result is rather satisfying. [Deepak] has also experimented with an Arduino driven version with a slightly different rhythm.

We haven’t seen too many projects using optical drive lens assemblies, but we’re sure there must be other applications. If you end up using one to agitate biological samples or build an awesome laser projector, be sure to hit up the tips line. Video after the break.

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Active Strain Relief for 3D-Printer Filament

Buying 3D-printer filament is little like eating potato chips: you can’t stop at just one. You start with basic black PLA, then you need a particular color for a special project, then you start experimenting with different plastics, and before you know it, you’ve got dozens of reels lined up. Trouble is, unless you move the in-use reel right over the printer, the filament can get a bit unruly as the printer sucks it up. What to do?

How about building an active strain relief system for your filament collection? That what [Daniel Harari] chose to do, and we have to say that it looks pretty slick. The idea is to keep the filament slack before it enters the printer’s extruder no matter where the reel is positioned relative to the printer. The active bit is a little like a low-force extruder, using a couple of pinch rollers from an old 2D-printer to pay out filament when needed. A clever sensor, consisting of a 3D-printed funnel and a copper wire contact loop, detects when the printer has taken up all the slack in the filament and triggers a payout from the feeder. In a nice touch, the feeder motor is controlled by a couple of 555s rather than a microcontroller. The short clip below shows the feeder being triggered and paying out a little more slack.

In the final analysis, this is just another in a long series of filament management projects, from dry-boxes to filament meters to end-of-spool alarms. It may be overkill, but [Daniel] put a lot of thought into it, which we always appreciate.

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