Author: Al Williams

4436 Articles

Using Metal Screws In Plastic Parts

April 10, 2026 by 8 Comments

Machine screws aren’t made for wood or sheet metal, they make specific screws for those applications. You probably also know there are special screws for plastic. But did you know there are at least two distinct types? In a recent video, [Lost in Tech] show us different types of plastic screws, including thermal camera shots of screws driving into 3D printed parts, along with tests using a torque driver.

We have often used “any old” screw in printed parts, which usually works OK. We’ve also used threaded inserts or captive nuts, classic choices. One of the issues with screws or inserts is that you have to get accurately sized holes in your 3D prints.

In addition to learning about the types of screws and how best to accommodate them, he also developed a free web-based tool that does all the math for you.

Of course, there are cases when you do need a threaded insert. In particular, the plastic screws will tend to wear the plastic each time you insert them. If you expect the screw to go in and out many times, this might not be the right technique for you. On the other hand, if you think you might remove and replace the screws a few dozen times over the life of the part, this might be attractive.

We’ve covered self-tapping screws in plastic before, but, as the video shows, not all of them are created equal. And, of course, there are always heat-set inserts.

Continue reading “Using Metal Screws In Plastic Parts” →

Bacteria Marching To The Beat Of A Tiny Drum

April 10, 2026 by 8 Comments

Traditionally, identifying a bacterium requires peering through a microscope. Researchers from TU Delft want to trade your eyes for your ears when identifying bacteria. This is possible because they’ve crafted nanoscale drums that convert bacteria’s movement into sound.

The technique originated when Delft researchers noticed something odd. If a living bacterium were on a graphene sheet, it would beat a distinctive pattern that you can detect with a laser. Each drumhead consists of two graphene sheets laid over an 8-micrometer-wide cavity. The sheets are less than a nanometer thick.

The sounds are due to the subtle motion of the tiny lifeform. Scientists have known about these motions, but previously had to measure them en masse. The tiny drums can respond to a single organism, typically about 1 to 10 micrometers in size.

Graphene makes this sensor possible because it is thin enough to behave like a drum with such a tiny force, yet also strong enough to support the bacterium. At first, the technique was simply to determine if antibiotics were killing the bacteria. However, they found that specific bacteria produced audio with unique spectrograms.

It is foolproof, but machine language models can identify among three common bacteria with nearly 90% accuracy. The next step is to reduce the high-tech research setup to something practical for a hospital or doctor’s office. Early prototypes are now in use in two hospitals.

We’ve seen the benefits of automated microscopes that can detect a particular disease. This technology, refined, could go even further.

USB, Abstracted

April 9, 2026 by 12 Comments

Modern technology builds on abstractions. Most application programmers today don’t know what a non-maskable interrupt is, nor should they have to. Even fewer understand register coloring or reservation stations for instruction scheduling, and fewer still can explain the physics behind the transistors in the CPU. Sometimes tech starts out where you need to know everything (programming a bare-metal microprocessor, for example) and then evolves to abstraction. That’s where [WerWolv] wants to get you for writing USB code using the recent post USB for Software Developers.

Many USB tutorials assume you want to know about the intricacies of protocol negotiation, information about the hardware layer, and that you are willing to write a Linux kernel module to provide a driver. But thanks to abstraction, none of this has been absolutely necessary for many use cases for a long time.

While the post focuses on Linux, there is libusb for Windows. We presume the same principles would apply, more or less.

Continue reading “USB, Abstracted” →

[Kerry Wong] Finds SMD Test Clips

April 9, 2026 by 9 Comments

One of the many problems you run into when you work with SMD parts is trying to probe the little tiny pins. While we usually watch [Kerry Wong’s] videos for the oscilloscopes, it makes sense that he’d also be looking for probes. The video below shows some cheap probes from China that can clamp onto tiny QFP pins.

The probes look a little like tiny needles, but the needle part isn’t conductive. When you push them, very tiny and rigid clamps come out. On the other end is a pin that will take a female header or, of course, you could connect another test lead to that pin.

Continue reading “[Kerry Wong] Finds SMD Test Clips” →

Need A Reactalyser?

April 9, 2026 by 17 Comments

We’ve noticed a recent surge in people recreating old projects from vintage electronics magazines, and we approve. After all, parts and PCBs are easier to get than ever, so other than replacing obsolete parts, it is usually much easier to build these projects now compared to when they first appeared. The latest one we’ve noticed was [Anthony Francis-Jones’] build of the “Reactalyser” from a 1968 edition of Practical Electronics. Check it out in the video below.

You may ask yourself what a reactalyser could be. We did too. Our guess was extremely far off, since we thought it might have to do with reactance.

We liked the retro-look radio that [Anthony] used as a case. He changed the circuit to use an OC71 PNP transistor and replaced a mechanical part of the device with more electronics. So this isn’t a totally faithful reproduction, but it does keep the spirit of the device.

This might seem like an odd circuit for something that would be totally trivial to make with a microcontroller. However, these kinds of circuits were very common prior to simple-to-use computers.

If you like these old retro builds, check out some of the ones we’ve featured from [Bettina Neumryr]. We need a name for this activity. We’ll suggest retromagging. Give us your entry in the comments. Continue reading “Need A Reactalyser?” →

WolfIP Doesn’t Allocate

April 9, 2026 by 28 Comments

For some types of embedded systems — especially those that are safety-critical — it’s considered bad form to dynamically allocate memory during operation. While you can usually arrange for your own code to behave, it’s the libraries that get you. In particular, it is hard to find a TCP/IP stack that doesn’t allocate and free memory all over the place. Unless you’ve found wolfIP.

The library supports a BSD-like non-blocking socket API. It can act as an endpoint, but can also support multiple interfaces and forwarding if you were building something like a router. It doesn’t appear to be bare-bones either. In addition to the normal things you’d expect for IPv4, there’s also ICMP, IPSEC, ARP, DHCP, DNS, and HTTP with or without SSL TLS. There is also a FIPS-compliant implementation of WireGuard for VPN, although it is not directly compatible with standard WireGuard, only with other instances of itself (known as wolfGuard). There is a Linux kernel module for WolfGuard, though.

The code should be fairly easy to port, and it includes a binding for FreeRTOS already. If you’ve used wolfIP, let us know in the comments.

If you want to really get down to the low-level, try this project. Of, if you want a refresher on basics, we can help with that, too.

Thermostat? Do It With A 555!

April 7, 2026 by 19 Comments

It is a running gag around here that whenever a project posts, someone will inevitably point out that it could have been done with a 555 timer IC. [Stephen Woodward] went the opposite way and built a simple thermostat using the ubiquitous chip.

To be fair, this isn’t some sophisticated PID controller — it’s basically a bang-bang controller. Since the device has a comparator and the circuits use a thermistor, it seems like a clever but simple idea on the surface. However, there are some neat tricks. For example, if you tie the 555 threshold pin to Vdd, then the trigger pin acts as an inverting analog comparator. Another nice feature: the setpoint depends on a resistance ratio, so there is no need for a precise input voltage reference.

A simple circuit change can switch the circuit to power a heater or a cooler. The chip can handle a surprising amount of power, but for some applications, you may need some output drive circuitry. The simple circuit even has hysteresis, which you can set with a different resistor. Pretty impressive for a cheap chip, two resistors, a thermistor, and a battery.

We’ve seen a lot of strange 555 circuits in our contests. We even had a 555 Timer Contest.