A Modchip For A Fridge

July 21, 2024 by 52 Comments

An annoying fridge that beeps incessantly when the door is open too long should be an easy enough thing to fix by disconnecting the speaker, but when as with [kennedn]’s model it’s plumbed in and the speaker is inaccessible, what’s to be done? The answer: create a mod chip for a fridge.

While the fridge electronics themselves couldn’t be reached, there was full access to a daughterboard with the fridge controls. It should be easy enough to use them to turn off the alarm, but first a little reverse engineering was required. It used a serial communication with an old-school set of shift registers rather than a microcontroller, but it soon became apparent that the job could be done by simply pulling the buttons down. In a move that should gladden the heart of all Hackaday readers then, the modchip in question didn’t even have to be a processor, instead it could be the venerable 555 timer. Our lives are complete, and the fridge is no longer annoying.

The 555 is unashamedly a Hackaday cliche, but even after five decades it still bears some understanding.

A cartoon of the Sun above a windmill and a solar panel with a lightning bolt going to a big grey gear with "AAAp" written on it. A small "e-" on a circle is next to it, indicating electricity transfer. Further to the right is an ADP molecule connected to a curved arrow going through the AAAp gear to turn into ATP. Three cartoon shapes, presumably illustrating biological processes are on the right with arrows pointing from the ATP.

Powering Biology With Batteries

July 21, 2024 by 18 Comments

We’ve all been there — you forgot your lunch, but there are AC outlets galore. Wouldn’t it be so much simpler if you could just plug in like your phone? Don’t try it yet, but biologists have taken us one step further to being able to fuel ourselves on those sweet, sweet electrons.

Using an “electrobiological module” of 3-4 enzymes, the amusingly named AAA (acid/aldehyde ATP) cycle regenerates ATP in biological systems directly from electricity. The process takes place at -0.6 V vs a standard hydrogen electrode (SHE), and is compatible with biological transcription/translation processes like “RNA and protein synthesis from DNA.”

The process isn’t dependent on any membranes to foul or more complicated sets of enzymes making it ideal for in vitro synthetic biology since you don’t have to worry about keeping as many components in an ideal environment. We’re particularly interested in how this might apply to DNA computing which we keep being promised will someday be the best thing since the transistor.

Maybe in the future we’ll all jack in instead of eating our daily food pill? If this all seems like something you’ve heard of before, but in reverse, maybe you’re thinking of microbial fuel cells.

Ask Hackaday: Should We Teach BASIC?

July 21, 2024 by 184 Comments

Suppose you decide you want to become a novelist. You enroll in the Hackaday Famous Novelists School where your instructor announces that since all truly great novels are written in Russian, our first task will be to learn Russian. You’d probably get up and leave. The truth is, what makes a great (or bad) novel transcends any particular language, and you could make the same argument for programming languages.

Despite the pundits, understanding the basics of how computers work is more important than knowing C, Java, or the language of the week. A recent post by [lackofimagination] proposes that we should teach programming using BASIC. And not a modern whizz-pow BASIC, but old-fashioned regular BASIC as we might have used it in the 1980s.

Certainly, a whole generation of programmers cut their teeth on BASIC. On the other hand, the programming world has changed a lot since then. While you can sort of apply functional and object-oriented techniques to any programming language, it isn’t simple and the details often get in the way of the core ideas.

Still, some things don’t change. The idea of variables, program flow, loops, and arrays all have some parallel in just about anything, so we can see some advantages to starting out simply. After all, you don’t learn to drive by trying it out in the Indy 500, right?

What do you think? If you were teaching programming today, would you start with BASIC? Or with something else? You can modernize a little bit with QB64. Or try EndBasic which just recently had a new release.

Welding Wood Is As Simple As Rubbing Two Sticks Together

July 21, 2024 by 12 Comments

Can you weld wood? It seems like a silly question — if you throw a couple of pieces of oak on the welding table and whip out the TIG torch, you know nothing is going to happen. But as [Action Lab] shows us in the video below, welding wood is technically possible, if not very practical.

Since experiments like this sometimes try to stretch things a bit, it probably pays to define welding as a process that melts two materials at their interface and fuses them together as the molten material solidifies. That would seem to pose a problem for wood, which just burns when heated. But as [Action Lab] points out, it’s the volatile gases released from wood as it is heated that actually burn, and the natural polymers that are decomposed by the heat to release these gases have a glass transition temperature just like any other polymer. You just have to heat wood enough to reach that temperature without actually bursting the wood into flames.

His answer is one of the oldest technologies we have: rubbing two sticks together. By chucking a hardwood peg into a hand drill and spinning it into a slightly undersized hole in a stick of oak, he created enough heat and pressure to partially melt the polymers at the interface. When allowed to cool, the polymers fuse together, and voila! Welded wood. Cutting his welded wood along the joint reveals a thin layer of material that obviously underwent a phase change, so he dug into this phenomenon a bit and discovered research into melting and welding wood, which concludes that the melted material is primarily lignin, a phenolic biopolymer found in the cell walls of wood.

[Action Lab] follows up with an experiment where he heats bent wood in a vacuum chamber with a laser to lock the bend in place. The experiment was somewhat less convincing but got us thinking about other ways to exclude oxygen from the “weld pool,” such as flooding the area with argon. That’s exactly what’s done in TIG welding, after all. Continue reading “Welding Wood Is As Simple As Rubbing Two Sticks Together” →

All About PNP Transistors

July 21, 2024 by 21 Comments

In the early days, PNP bipolar transistors were common, but the bulk of circuits you see today use NPN transistors. As [Aaron Danner] points out, many people think PNP transistors are “backward” but they have an important role to play in many circuits. He explains it all in a recent video you can see below.

He does explain why PNP transistors don’t perform as well as corresponding NPN transistors, but they are still necessary sometimes. Once you get used to it, they are no problem to handle at all. Common cases where you want a PNP are, for example, when you want to switch a voltage instead of a ground. There are also certain amplifier configurations that need PNP units.

Like an NPN transistor, a PNP can operate in saturation, linear operation, reverse active, or it can be cut off. [Aaron] shows you how to bias a transistor and you’ll see it isn’t much different from an NPN except the base-emitter diode junction is reversed.

As you might expect, current has to flow through that diode junction to turn the transistor on. The arrow points in the direction of the diode junction. If you want a refresher on transistor biasing, we got you. Sure, you don’t need to do it every day now, but it still is a useful skill to have.

Continue reading “All About PNP Transistors” →

Sketch of the UED setup at EPFL, 1) Electron gun, 2) High-Voltage connector, 3) Photo-cathode, 4) Anode, 5) Collimating solenoid, 6) Steering plates, 7) Focusing solenoid, 8) RF cavity, 9) Sample holder, 10) Cryostat, 11) Electron detector, 12) Turbo pump, 13) Ion gauge. Credit: Proceedings of the National Academy of Sciences (2024). DOI: 10.1073/pnas.2316438121

Using Femtosecond Laser Pulses To Induce Metastable Hidden States In Magnetite

July 20, 2024 by No comments

Hidden states are a fascinating aspect of matter, as these can not normally be reached via natural processes (i.e. non-ergodic), but we can establish them using laser photoexcitation. Although these hidden states are generally very unstable and will often decay within a nanosecond, there is evidence for more persistent states in e.g. vanadates. As for practical uses of these states, electronics and related fields are often mentioned. This is also the focus in the press release by the Ecole Polytechnique Federale de Lausanne (EPFL) when reporting on establishing hidden states in magnetite (Fe3O4), with the study published in PNAS (Arxiv preprint link).

[B. Truc] and colleagues used two laser frequencies to either make the magnetite more conductive (800 nm) or a better insulator (400 nm). The transition takes on the order of 50 picoseconds, allowing for fairly rapid switching between these metastable states. Naturally, turning this into practical applications will require a lot more work, especially considering the need for femtosecond pulsed lasers to control the process, which makes it significantly more cumbersome than semiconductor technology. Its main use at this point in time will remain a fascinating demonstration of these hidden states of matter.

Working Through The Art Of Electronics Exercises

July 20, 2024 by 10 Comments

[The Engineering Experience] has an ambitious series of videos. He’s working through circuit examples from the awesome book “The Art of Electronics.” In the latest installment, he’s looking at a pulse generator that uses bipolar transistors. So far, there are 43 videos covering different exercises.

If you’ve read the book — and you should — you know the examples and exercises sometimes have little explanation. Honestly, that’s good. You should try to work through them yourself first. But once you have an idea of how it works, hearing someone give their take on it may help you out. In fact, even if you don’t have the book, we’d suggest pausing the video and looking at the circuit to see what you can figure out before playing the explanation. You’ll learn more that way.

Admittedly, some of the early videos will be cakewalks for Hackaday readers. The first few, for example, walk through parallel and series resistors. However, if you are starting out or just want a refresher, you can probably enjoy all of them. The later ones get a bit more challenging.

If you want to double-check your work, you can simulate the circuit, too. Our simulation got 4.79 V and he computed 4.8, which is certainly close enough.

We do love “The Art of Electronics.” The book’s author also enjoys listening for aliens.

Continue reading “Working Through The Art Of Electronics Exercises” →