We take easy communications for granted these days. It’s no bother to turn on a lightbulb remotely via a radio link or sense the water level in your petunias, but how does a drilling rig sense data from the drill head whilst deep underground, below the sea bed? The answer is with mud pulse telemetry, about which a group of researchers have produced a study, specifically about modelling the signal impairments and strategies for maintaining the data rate and improving the signal quality.
If you’re still confused, mud pulse telemetry (MPT) works by sending a modulated pressure wave vertically through the column of mud inside the drilling tube. It’s essential to obtain real-time data during drilling operations on the exact angle and direction the drill bit is pointing (so it can be corrected) and details of geological formations so decisions can be made promptly. The goal is to reduce drilling time and, therefore, costs and minimize environmental impact — although some would strongly argue about that last point.
When you hand your new acquaintance one of your cards, there’s a chance you might feel an instant connection. But what if you could know almost instantly whether they felt the same way? With the Dr. Love card, you can erase all doubt.
As you may have guessed, the card uses Galvanic Skin Response. That’s the fancy term for the fact that your skin’s electrical properties change when you sweat, making it easier for electricity to pass through it. There are two sensors, one on each short end of the card where you would both naturally touch it upon exchange. Except this time, if you want to test the waters, you’ll have to wait 10-15 seconds while Dr. Love assesses your chemistry.
The doctor in this case is an RP2040-LCD-0.96, which is what it sounds like — a Raspberry Pi Pico with a small LCD attached. For the sensors, [Un Kyu Lee] simply used 8mm-wide strips of nickel. If you want to build your own, be sure to check out the build guide and watch the video after the break for a demonstration of Dr. Love in action.
Last time, we went over switching regulator basics – why they’re wonderful, how do you find a switching regulator chip for your purpose, and how to easily pick an inductor for one. Your datasheet should also tell you about layout requirements. However, it might not, or you might want to deviate from them – let’s go more in-depth on what those requirements are about.
Appreciate The Feedback
The two resistors on the right decide what your output voltage will be, and their output is noise-sensitive
There’s a few different switching regulator topologies. Depending on your regulator’s topology and how many components your chip contains, you might need some external components – maybe a Schottky diode, maybe a FET, or maybe even a FET pair. It’s often that the FET is built-in, and same goes for diodes, but with higher-current regulator (2 A to 3 A and above), it’s not uncommon to require an external one. For sizing up those, you’ll want to refer to the datasheet or existing boards.
Another thing is input and output capacitors – don’t skimp on those, because some regulators are seriously sensitive to the amount of capacitance they’re operating with. Furthermore, if you fail to consider things like capacitance dropping with voltage, you might make your regulator very unhappy – not that a linear regulator would be happy either, to be clear. We’ve covered an explainer on this recently – do check it out!
One thing you will likely need, is a feedback resistor divider – unless your switching regulator is pre-set for a certain voltage or is digitally controlled, you need to somehow point it to the right voltage, in an analog way. Quite a few switching regulators are set for a certain voltage output, but most of them aren’t, and they will want you to add a resistor divider to know what to output. There’s usually a formula for resistor divider calculation, so, pick a common resistor value, put it in as one of the resistors into the formula, get the other resistor value out of that formula, and see what’s the closest value you can actually buy. Don’t go below about 10 kΩ so that you don’t have unnecessary idle power consumption, but also don’t go too far above 100 kΩ to ensure good stability of the circuit. Continue reading “Switching Regulator Layout For Dummies”→
Apple is well-known for its secrecy, which is understandable given the high stakes in the high-end mobile phone industry. It’s interesting to get a glimpse inside its durability labs and see the equipment and processes it uses to support its IP68 ingress claims, determine drop ability, and perform accelerated wear and tear testing.
Check out these cool custom-built machines on display! They verify designs against a sliding scale of water ingress tests. At the bottom end is IPx4 for a light shower, but basically no pressure. Next up is IPx5, which covers low-pressure ambient-temperature spray jets from all angles – we really liked this machine! Finally, the top-end IPx7 and IPx8 are tested with a literal fire hose blast and a dip in a static pressure tank, simulating a significant depth of water. An Epson robot arm with a custom gripper is programmed to perform a spinning drop onto a hard surface in a repeatable manner. The drop surface is swapped out for each run – anything from a wooden sheet to a slab of asphalt can be tried. High-speed cameras record the motion in enough detail to resolve the vibrations of the titanium shell upon impact!
Accelerated wear and tear testing is carried out using a shake table, which can be adjusted to match the specific frequencies of a car engine or a subway train. Additionally, there’s an interview with the head of Apple’s hardware division discussing the tradeoffs between repairability and durability. He makes some good points that suggest if modern phones are more reliable and have fewer failures, then durability can be prioritized in the design, as long as the battery can still be replaced.
What was the worst thing about the 70s? Some might say the oil crisis, inflation, or even disco. Others might tell you it was 8-track tapes, no matter what was on them. I’ve heard that the side of the road was littered with dead 8-tracks. But for a while, they were the only practical way to have music in the car that didn’t come from the AM/FM radio.
If you know me at all, you know that I can’t live without music. I’m always trying to expand my collection by any means necessary, and that includes any format I can play at home. Until recently, that list included vinyl, cassettes, mini-discs, and CDs. I had an 8-track player about 20 years ago — a portable Toyo that stopped working or something. Since then, I’ve wanted another one so I can collect tapes again. Only this time around, I’m trying to do it right by cleaning and restoring them instead of just shoving them in the player willy-nilly.
Update: I Found a Player
I have since cleaned it.
A couple of weeks ago, I was at an estate sale and I found a little stereo component player and speakers. There was no receiver in sight. I tested the player with the speakers and bought them for $15 total because it was 75% off day and they were overpriced originally. While I was still at the sale, I hooked it up to the little speakers and made sure it played and changed programs.
Well, I got it home and it no longer made sound or changed programs. I thought about the play head inside and how dirty it must be, based on the smoker residue on the front plate of the player. Sure enough, I blackened a few Q-tips and it started playing sweet tunes again. This is when I figured out it wouldn’t change programs anymore.
I found I couldn’t get very far into the player, but I was able to squirt some contact cleaner into the program selector switch. After many more desperate button presses, it finally started changing programs again. Hooray!
If you follow the world of microcontrollers, then you’ll probably be familiar with the most recent crop of ten cent parts. They bring power and features previously the preserve of much more expensive chips into the super-budget arena, and they’re appearing in plenty of projects on these pages.
If you’re not familiar with them it can seem daunting to decide which one to use, so to help you [Zach of All Trades] is comparing two of the more common ones. The CH32V003 with a RISC-V core and the PY32F002 with an ARM Cortex M0+ core are both pretty similar on paper, but which should you use?
The video below gives a run-down of each part along with some demonstrations before making its conclusions. The ARM-based part isn’t as quick as the RISC-V one but has a slight edge on peripherals, while the support is where a potential winner emerges in the shape of the CH32. That should be the last word, but for that the PY32 has the distance advantage over its rival of ready availability.
So this look at two families of cheap microcontrollers reveals the pros and cons of each, but in reality it provides an introduction to two sets of powerful chips for pennies.
While most of us have likely spun up a virtual machine (VM) for one reason or another, venturing into the world of containerization with software like Docker is a little trickier. While the tools Docker provides are powerful, maintain many of the benefits of virtualization, and don’t use as many system resources as a VM, it can be harder to get the hang of setting up and maintaining containers than it generally is to run a few virtual machines. If you’ve been hesitant to try it out, this guide to getting a Docker container up and running is worth a look.
The guide goes over the basics of how Docker works to share system resources between containers, including some discussion on the difference between images and containers, where containers can store files on the host system, and how they use networking resources. From there the guide touches on installing Docker within a Debian Linux system. But where it really shines is demonstrating how to use Docker Compose to configure a container and get it running. Docker Compose is a file that configures a number of containers and their options, making it easy to deploy those containers to other machines fairly straightforward, and understanding it is key to making your experience learning Docker a smooth one.
While the guide goes through setting up a self-hosted document management program called Paperless, it’s pretty easy to expand this to other services you might want to host on your own as well. For example, the DNS-level ad-blocking software Pi-Hole which is generally run on a Raspberry Pi can be containerized and run on a computer or server you might already have in your home, freeing up your Pi to do other things. And although it’s a little more involved you can always build your own containers too as our own [Ben James] discussed back in 2018.
