Are your jellybeans getting stale? [lcamtuf] thinks so, and his guide to choosing op-amps makes a good case for rethinking what parts you should keep in stock.

For readers of a certain vintage, the term “operational amplifier” is almost synonymous with the LM741 or LM324, and with good reason. This is despite the limitations these chips have, including the need for bipolar power supplies at relatively high voltages and the need to limit the input voltage range lest clipping and distortion occur. These chips have appeared in countless designs over the nearly 60 years that they’ve been available, and the Internet is littered with examples of circuits using them.

For [lcamtuf], the abundance of designs for these dated chips is exactly the problem, as it leads to a “copy-paste” design culture despite the far more capable and modern op-amps that are readily available. His list of preferred jellybeans includes the OPA2323, favored thanks to its lower single-supply voltage range, rail-to-rail input and output, and decent output current. The article also discussed the pros and cons of FET input, frequency response and slew rate, and the relative unimportance of internal noise, pointing out that most modern op-amps will probably be the least thermally noisy part in your circuit.

None of this is to take away from how important the 741 and other early op-amps were, of course. They are venerable chips that still have their place, and we expect they’ll be showing up in designs for many decades to come. This is just food for thought, and [lcamtuf] makes a good case for rethinking your analog designs while cluing us in on what really matters when choosing an op-amp.

There’s an old joke: What do you get someone who has everything? A place to put it. For hackers like [Christian], everything is a hoard of priceless electronic components. His solution is using small zipper bags, either regular plastic or anti-static. These attach using hook and loop fastener to plastic binder sheets which then live in a binder. Combined with some custom printed labels and a few other tricks, it makes for a nice system, as you can see in the video below.

Honestly, we’ve done something similar before, using a binder with little pockets, but the bag and custom labels beat our system. He even has QR codes on some of them to locate data sheets easily. Seems like a barcode for inventory management might have been good, too.

Some advice from us. If you are just starting out, this might seem like overkill. But if you start out doing something — this or something else — then ten years from now, you won’t have to be like us and think, “I’d get everything organized, but it is going to take months to work through what I already have…” That usually makes it a project you never really get started with. Develop good habits early!

Even if you don’t want to store your components this way, his binder hacks probably work for lots of other things, too. It isn’t as flashy as some systems we’ve seen, but it is very practical. If only you didn’t have to turn the pages in the binder yourself.

If you’re looking to get into flying first-person view (FPV) remote controlled aircraft, there’s an incredible amount of information available online. Seriously, it’s ridiculous. In fact, between the different forums and the countless YouTube videos out there, it can be difficult to sort through the noise and actually find the information you need.

What if there was one location where FPV folks could look up hardware, compare notes, and maybe even meet up for the occasional flight? That’s the idea behind the recently launched DIYFPV. In its current state the website is a cross between a social media platform, a hardware database, and a tech support forum.

Being able to look up parts to see who has them in stock and for what price is certainly handy, and is likely to become a very valuable resource, especially as users start filling the database with first-hand reviews. There’s no shortage of social media platforms where you can post and chat about FPV, but pairing that with a dedicated tech support section has promise. Especially if the solutions it produces start getting scrapped by show up in search engines.

But the part of DIYFPV that has us the most interested is the interactive builder tool. As explained in the announcement video below, once this feature goes live, it will allow users to pick parts from the database and virtually wire them together. Parts are represented by high-quality illustrations that accurately represent connectors and solder pads, so you won’t be left guessing where you’re supposed to connect what. Schematics can be shared with others to help with troubleshooting or if you want to get feedback.

The potential here is immense. Imagine a function to estimate the mass of the currently selected electronics, or a simulation of how much current it will draw during flight. It’s not clear how far DIYFPV plans on taking this feature, but we’re eager to find out.

If you’ve ever worked with adding lithium-ion batteries to one of your projects, you’ve likely spent some quality time with a TP4056. Whether you implemented the circuit yourself, or took the easy way out and picked up one of the dirt cheap modules available online, the battery management IC is simple to work with and gets the job done.

But there’s always room for improvement. In a recent video, [Det] and [Rich] from Learn Electronics Repair go over using a more modern battery management board that’s sold online as the MH-CD42. This board, which is generally based on a clone of the IP5306, seems intended for USB battery banks — but as it so happens, plenty of projects that makers and hardware hackers work on have very similar requirements.

So not only will the MH-CD42 charge your lithium-ion cells when given a nominal USB input voltage (4.5 – 5 VDC), it will also provide essential protections for the battery. That means looking out for short circuits, over-charge, and over-discharge conditions. It can charge at up to 2 A (up from 1 A on the TP4056), and includes a handy LED “battery gauge” on the board. But perhaps best of all for our purposes, it includes the necessary circuitry to boost the output from the battery up to 5 V.

If there’s a downside to this board, it’s that it has an automatic cut-off for when it thinks you’ve finished using it; a feature inherited from its USB battery bank origins. In practice, that means this board might not be the right choice for projects that aren’t drawing more than a hundred milliamps or so.

A common theme in modern consumer electronics is having a power button that can be tapped to turn the device on, but needs to be held down when it’s time to shut it off. [R. Jayapal] had noticed a circuit design for this setup when using DC and decided to create a version that could handle AC-powered loads.

The circuit relies on a classic optoisolated triac to switch the AC line, although [R. Jayapal] notes that a relay would also work. The switch circuit consists of two transistors, a comparator, a flip flop and a monostable. As you might expect, the button triggers the flip flops to turn the triac on. However, if you hold the switch for more than a few seconds, a capacitor charges and causes the comparator to trip the output flip flop.

The DC circuit that inspired this one is naturally a bit simpler, although we might have been tempted to simply use the output of that circuit to drive a relay or triac. On the other hand, the circuit is set up to allow you to adjust the time delay easily.

Given the collection of parts, though, we wonder if you couldn’t press some 555s into service for this to further reduce the part count. If relays are too old-fashioned for you, you can always use a solid-state relay or make your own.

Imagine the power to clone your favorite LEGO piece—not just any piece, but let’s say, one that costs €50 second-hand. [Balazs] from RacingBrick posed this exact question: can a 3D scanner recreate LEGO pieces at home? Armed with Creality’s CR-Scan Otter, he set out to duplicate a humble DUPLO sheep and, of course, tackle the holy grail of LEGO collectibles: the rare LEGO goat.

The CR-Scan Otter is a neat gadget for hobbyists, capable of capturing objects as small as a LEGO piece. While the scanner proved adept with larger, blocky pieces, reflective LEGO plastic posed challenges, requiring multiple scans for detailed accuracy. With clever use of 3D printed tracking points, even the elusive goat came to life—albeit with imperfections. The process highlighted both the potential and the limitations of replicating tiny, complex shapes. From multi-colored DUPLO sheep to metallic green dinosaur jaws, [Balazs]’s experiments show how scanners can fuel customization for non-commercial purposes.

For those itching to enhance or replace their builds, this project is inspiring but practical advice remains: cloning LEGO pieces with a scanner is fun but far from plug-and-play. Check out [Balazs]’s exploration below for the full geeky details and inspiration.

Oscillators may use crystals as precise tuned circuits. If you have a vector network analyzer (VNA) — or even some basic test equipment — you can use it to learn the parameters of a crystal. [All Electronics Channel] has the details, and you can see how in the video below.

There was a time when a VNA was an exotic piece of gear, but these days they are relatively common. Crystal parameters are important because crystals have a series resonance and a parallel resonance and they are not at the same frequency. You also may need to know how much loading capacitance you have to supply to get the crystal at the right frequency.

Sometimes, you want to pull the crystal frequency, and the parameters will help you figure that out, too. It can also help if you have a crystal specified as series in a parallel-mode oscillator or vice versa.

If you don’t have a VNA, you can use a tracking signal generator, as [Grégory] shows towards the middle of the video. The quality of a tuned circuit depends on the Q factor, and crystals have a very high Q factor.

We did something similar in 2018. The other way to pull a crystal frequency is a bit extreme.

Aluminium drinks cans make a great source of thin sheet metal which can be used for all manner of interesting projects, but it’s safe to say that retrieving a sheet of metal from a can is a hazardous process. Cut fingers and jagged edges are never far away, so [Kevin Cheung]’s work in making an easy can cutter is definitely worth a look.

Taking inspiration from a rotary can opener, he uses a pair of circular blades in an adjustable injection moulded plastic frame. If you’ve used a pipe cutter than maybe you are familiar with the technique, as the blade rotates round the can a few times it slowly scores and cuts through the metal. Doing the job at both ends of the can reveals a tube, which cna be then cut with scissors and flattened to make a rectangular metal sheet. Those edges are probably sharp, but nothing like the jagged finger-cutters you’d get doing the same by hand. The full video can be seen below the break, and the files to 3D print the plastic parts of the cutter can be found at the bottom of a page describing the use of cans to make a shingle roof.

If you’ve been tearing electronic devices apart for long enough, you’ll know that the old gear had just as many mysteries within as the newer stuff. The parts back then were bigger, of course, but often just as inscrutable as the SMD parts that populate boards today. And the one part that always baffled us back in the days of transistor radios and personal cassette players was those little silver boxes with a hole in the top and the colorful plug with an inviting screwdriver slot.

We’re talking about subminiature intermediate-frequency transformers, of course, and while we knew their purpose in general terms back then and never to fiddle with them, we never really bothered to look inside one. This teardown of various IF transformers by [Unrelated Activities] makes up somewhat for that shameful lack of curiosity. The video lacks narration, relying on captions to get the point across that these once-ubiquitous components were a pretty diverse lot despite their outward similarities. Most had a metal shell protecting a form around which one or more coils of fine magnet wire were wrapped. Some had tiny capacitors wired in parallel with one of the coils, too.

Perhaps the most obvious feature of these IF transformers was their tunability, thanks to a ferrite cup or slug around the central core and coils. The threaded slug allowed the inductance of the system to be changed with the turn of a screwdriver, preferably a plastic one. [Unrelated] demonstrates this with a NanoVNA using a nominal 10.7-MHz IFT, probably from an FM receiver. The transformer was tunable over a 4-MHz range.

Sure, IFTs like these are still made, and they’re not that hard to find if you know where to look. But they are certainly less common than they used to be, and seeing what’s under the hood scratches an itch we didn’t even realize we had.