You think of op amps as amplifiers because, no kidding, it is right in the name. But just like some people say, “you could do that with a 555,” [Doctor Volt] might say, “you can do that with an op amp.” In a recent video, you can see below, he looks at simulations and breadboards for five applications that aren’t traditional amplifiers.

Of course, you can split hairs. A comparator is sort of an amplifier with some very specific parameters, but it isn’t an amplifier in the classic sense.

In addition to comparators, there’s a flip flop, a few oscillators, and a PWM audio over optical transmitter and receiver. If you want to test your understanding of op amps, you can try to analyze the different circuits to see if you can explain how they work.

Op amps are amazing for analog design since you don’t have to build up high-quality amplifier blocks from discrete devices. Even the worst op amp you can buy is probably better than something you have the patience to design in a few minutes with a FET or a bipolar device. Fair to say that we do enjoy these oddball op amp circuits.

How far can you stretch a measuring tape before it buckles? The answer probably depends more on the tape than the user, but it does show how sturdy the coiled spring steel rulers can be. [Gengzhi He et. al.] may have been playing that game in the lab at UC San Diego when they hit upon the idea for a new kind of low-cost robotic gripper.

With the lovely backronym “GRIP-tape” — standing for Grasping and Rolling in Plane — you get a sense for what this effector can do. Its two “fingers” are each made of loops of doubled-up measuring tape bound together with what looks suspiciously like duck tape. With four motors total, the fingers can be lengthened or shortened by spooling the tape, allowing  a reaching motion, pivot closer or further apart for grasping, and move-in-place like conveyor belts, rotating the object in their grasp.

The combination means it can reach out, grab a light bulb, and screw it into a socket. Or open and decant a jar of spices. Another video shows the gripper reaching out to pick a lemon, and gently twist it off the tree. It’s quite a performance for a device with such modest components.

At the moment, the gripper is controlled via remote; the researchers plan on adding sensors and AI autonomous control. Read all the details in the preprint, or check below the fold to watch the robot in action.

This is hardly the first time we’ve highlighted a grabby robot. We’ve seen belts, we’ve seen origami — but this is the first time we’ve seen a measuring tape. Have you seen a cool robot? Toss us a tip. We’d love to hear from you.

Tip of the hat to reader [anonymouse] for pointing this one out.

We’ve all had times where we knew we had some part but we had to go searching for it all over as it wasn’t where we thought we put it. Organizing the numerous components, parts, and supplies that go into your projects can be a daunting task, especially if you use the same type of part at different times for different projects. It helps to have a framework to keep track of all the small details. Binner is an open source project that aims to allow you to easily maintain a database that can be customized to your use.

In a recent video for DigiKey, [Byte Sized Engineer] used Binner to track the locations of his components and parts in his freshly organized workshop. Binner already has the ability to read the labels used by well-known electronics suppliers via a barcode scanner, and uses that information to populate your inventory. It even grabs quantities and links in a datasheet for your newly added part. The barcode scanner can also be used to retrieve the contents of a location, so with a single scan Binner can bring up everything residing at that location.

Binner can be run locally so there isn’t the concern of putting in all the effort to build up your database just to have an internet outage make it inaccessible. Another cool feature is that it allows you to print labels, you can customize the fields to display the values you care about.

The project already has future plans to tie into a “smart bin” system to light up the location of your component — a clever feature we’ve seen implemented in previous setups.

An electric typewriter is a rare and wonderful thrift store find, and even better if it still works. Unfortunately, there’s not as much use for these electromechanical beauties, so if you find one, why not follow [Konstantin Schauwecker]’s lead and turn it into a printer?

The portable typewriter [Konstantin] found, a Silver Reed 2200 CR, looks like a model from the early 1980s, just before PCs and word processing software would sound the death knell for typewriters. This machine has short-throw mechanical keys, meaning that a physical press of each key would be needed rather than electrically shorting contacts. Cue the order for 50 low-voltage solenoids, which are arranged in rows using 3D printed holders and aluminum brackets, which serve as heat sinks to keep the coils cool. The solenoids are organized into a matrix with MOSFET drivers for the rows and columns, with snubber diodes to prevent voltage spikes across the coils, of course. A Raspberry Pi takes care of translating an input PDF file into text and sending the right combination of GPIO signals to press each key.

The action of the space bar is a little unreliable, so page formatting can be a bit off, but other than that, the results are pretty good. [Konstantin] even managed to hook the printer up to his typewriter keyboard, which is pretty cool, too.

There seems to be nothing a 555 can’t do. We’ve seen it before, but [electronzapdotcom] reminds us you can use a 555 and a few parts to make a reasonable touch switch in this video, embedded below.

The circuit uses some very large resistors so that noise from your body can overcome the logic level on the trigger and threshold inputs. You can easily adapt this idea if you need a simple touch switch. Though we imagine this circuit wouldn’t work well if you were in a quiet environment. We suspect 50 or 60 Hz hum is coupling through your finger and triggering the pins, but it could be a different effect.

How reliable is it? Beats us. The circuit is a bistable, so essentially your finger pumps a signal into a flip-flop. This is old trick, but could be useful. Of course, if you really need a touch switch, you have plenty of options. You can get little modules. Or, directly measure skin resistance.

First of all, we’d like to give a big shout-out to [Afrotechmods]! After a long hiatus, he has returned to YouTube with an awesome new video all about op-amp characteristics, looking at the relatively awful LM741 in particular. His particular way of explaining things has definitely helped many electronics newbies to learn new concepts quickly!

Operational amplifiers have been around for a long time. The uA741, now commonly known as the LM741, was indeed an incredible piece of technology when it was released. It was extremely popular through the 1970s and onward as it saved designers the chore of designing a discrete amplifier. Simply add a few external components, and you have a well-behaved amplifier.

But as the years went on, many new and greatly improved op-amps have been developed, but either because of nostalgia or reticence, many in the field (especially, it seems, professors teaching electronics) have continued to use the LM741 in examples and projects. This is despite its many shortcomings:

• Large input offset voltage
• Large input offset current
• Low gain-bandwidth product
• Miserable slew rate of only 0.5V/uS

And that’s not even the full list. Newer designs have vastly improved all of these parameters, often by orders of magnitude, yet the LM741 still appears in articles aimed at those new to electronics, even in 2025. There are literal drop-in replacements for the LM741, such as the TLC081 (not to be confused with the similarly named FET-input TL081), which has 32 times the slew rate, 10 times the gain-bandwidth product, and an input offset voltage almost 2 orders of magnitude better!

So, check out the full video below, learn about op-amp parameters, and start checking out modern op-amps!

After seeing some of the interesting clock builds we’ve featured recently, [shiura] decided to throw their hat in the ring and sent us word about their incredible 3D printed hybrid clock that combines analog and digital styles.

While the multiple rotating rings might look complex from the front, the ingenious design behind the mechanism is powered by a single stepper motor. Its operation is well explained in the video below, but the short version is that each ring has a hook that pushes its neighboring ring over to the next digit once it has completed a full rotation. So the rightmost ring rotates freely through 0 to 9, then flips the 10-minute ring to the next number before starting its journey again. This does mean that the minute hand on the analog display makes a leap forward every 10 minutes rather than move smoothly, but we think its a reasonable compromise.

Beyond the 28BYJ-48 geared stepper motor and its driver board, the only other electronics in the build is a Seeed Studio XIAO ESP32C6 microcontroller. The WiFi-enabled MCU is able to pull the current time down from the Internet, but keep it mind it takes quite awhile for the mechanism to move all the wheels; you can see the process happen at 60x speed in the video.

If you’re looking to recreate this beauty, the trickiest part of this whole build might be the 3D print itself, as the design appears to make considerable use of multi-material printing. While it’s not impossible to build the clock with a traditional printer, you’ll have to accept losing some surface detail on the face and performing some well-timed filament swaps.

[shirua] tells us they were inspired to send their timepiece in after seeing the post about the sliding clock that just went out earlier in the week.

We’ve seen plenty of motor projects, but [Jeremy]’s DIY Tubular Linear Motor is a really neat variety of stepper motor in a format we certainly don’t see every day. It started as a design experiment in making a DIY reduced noise, gearless actuator and you can see the result here.

Here’s how it works: the cylindrical section contains permanent magnets, and it slides back and forth through the center of a row of coils depending on how those coils are energized. In a way, it’s what one would get by unrolling a typical rotary stepper motor. The result is a gearless (and very quiet) linear actuator that controls like a stepper motor.

While a tubular linear motor is at its heart a pretty straightforward concept, [Jeremy] found very little information on how to actually go about making one from scratch. [Jeremy] acknowledges he’s no expert when it comes to motor design or assembly, but he didn’t let that stop him from iterating on the concept (which included figuring out optimal coil design and magnet spacing and orientation) until he was satisfied. We love to see this kind of learning process centered around exploring an idea.

We’ve seen DIY linear motors embedded in PCBs and even seen them pressed into service as model train tracks, but this is the first time we can recall seeing a tubular format.

Watch it in action in the short video embedded below, and dive into the project log that describes how it works for added detail.

Tektronix must have been quite a place to work back in the 1980s. The company offered a bewildering selection of test equipment, and while the digital age was creeping in, much of their gear was still firmly rooted in the analog world. And some of the engineering tricks the Tek wizards pulled off are still the stuff of legend.

One such gem of analog design was the SG505, an ultra-low-distortion oscillator module that [Paul] is trying to replicate with modern parts. That’s a tall order since not only did the original specs on this oscillator call for less than 0.0008% total harmonic distortion over a frequency range of 20 Hz to 20 kHz, but a lot of the components it used are no longer manufactured. Tek also tended to use a lot of custom parts, especially mechanical ones like the barrel switch used to select attenuation levels in the SG505, leaving [Paul] no choice but to engineer his way around them.

So far, [Paul] has managed to track down most of the critical components or source suitable substitutes. One major win was locating the original J-FET Tek used in the oscillator’s AGC circuit. One part that’s proven more elusive is the potentiometer that Tek used to adjust the frequency; who knew that finding a dual-gang precision wirewound 10k single-turn pot with no physical stop would be such a chore?

[Paul] still seems to be very much in the planning stages of this project yet, and that’s probably for the best since projects such as these live and die on proper planning. We’re keen to see how this develops, and we’re very much looking forward to seeing the FFT results. We also imagine he’ll be busting out his custom curve tracer at some point in the build, too.

We have all seen optimistic claims for electronic products that fail to match the reality, and [Electronic Wizard] is following one up in a recent video. Can a relatively small IGBT really switch 200 A as claimed by a dubious seller? Off to the datasheet to find out!

The device in question is from Toshiba, and comes in a TO-220 package. This itself makes us pause for a minute, because we suspect the pins on a TO220 would act more like fuses at a steady 200 A.

But in the datasheet, there it is: 200 A. Which would be great, but of course it turns out that this is the instantaneous maximum current for a few microsecond pulse. Even then it’s not finished, because while the continuous current is supposed to he half that, in the datasheet it specifies a junction temperature of 25 °C. The cooling rig required to maintain that with this transistor passing 200 A would we think be a sight to behold, so for all intents and purposes this can’t even switch a continuous 100 A. And the real figure is much less as you’d imagine, but it raises an important point. We blindly read datasheets and trust them, but sometimes we should engage brain before releasing the magic smoke.

In today’s “futuristic tech you can get for $5”, [RealCorebb] shows us a gesture sensor, one of the sci-fi kind. He was doing a desktop clock build, and wanted to add gesture control to it – without any holes that a typical optical sensor needs. After some searching, he’s found Microchip’s MGC3130, a gesture sensing chip that works with “E-fields”, more precise than the usual ones, almost as cheap, and with a lovely twist.

The coolest part about this chip is that it needs no case openings. The 3130 can work even behind obstructions like a 3D-printed case. You do need a PCB the size of a laptop touchpad, however — unlike the optical sensors easy to find from the usual online marketplaces. Still, if you have a spot, this is a perfect gesture-sensing solution. [RealCorebb] shows it off to us in the demo video.

This PCB design is available as gerbers+bom+schematic PDF. You can still order one from the files in the repo.  Also, you need to use Microchip’s tools to program your preferred gestures into the chip. Still, it pays off, thanks to the chip’s reasonably low price and on-chip gesture processing. And, [RealCorebb] provides all the explanations you could need, has Arduino examples for us, links all the software, and even provides some Python scripts! Touch-sensitive technology has been getting more and more steam in hacker circles – for instance, check out this open-source 3D-printed trackpad.

Fair warning: watching this hybrid manufacturing method for gear teeth may result in an uncontrollable urge to buy a fiber laser cutter. Hackaday isn’t responsible for any financial difficulties that may result.

With that out of the way, this is an interesting look into how traditional machining and desktop manufacturing methods can combine to make parts easier than either method alone. The part that [Paul] is trying to make is called a Hirth coupling, a term that you might not be familiar with (we weren’t) but you’ve likely seen and used. They’re essentially flat surfaces with gear teeth cut into them allowing the two halves of the coupling to nest together and lock firmly in a variety of relative radial positions. They’re commonly used on camera gear like tripods for adjustable control handles and tilt heads, in which case they’re called rosettes.

To make his rosettes, [Paul] started with a block of aluminum on the lathe, where the basic cylindrical shape of the coupling was created. At this point, forming the teeth in the face of each coupling half with traditional machining methods would have been tricky, either using a dividing head on a milling machine or letting a CNC mill have at it. Instead, he fixtured each half of the coupling to the bed of his 100 W fiber laser cutter to cut the teeth. The resulting teeth would probably not be suitable for power transmission; the surface finish was a bit rough, and the tooth gullet was a little too rounded. But for a rosette, this was perfectly acceptable, and probably a lot faster to produce than the alternative.

In case you’re curious as to what [Paul] needs these joints for, it’s a tablet stand for his exercise machine. Sound familiar? That’s because we recently covered his attempts to beef up 3D prints with a metal endoskeleton for the same project.

Thanks to [Ziggi] for the tip.