Raspberry Pi Pico Oscilloscope

June 26, 2021 by Danie Conradie 50 Comments

As you dive deeper into the world of electronics, a good oscilloscope quickly is an indispensable tool. However, for many use cases where you’re debugging low voltage, low speed circuits, that expensive oscilloscope is using only a fraction of its capabilities. As a minimalist alternative for these use cases [fhdm-dev] created Scoppy, a combination of firmware for the Raspberry Pi Pico and an Android app to create a functional oscilloscope.

As you would expect, the specifications are rather limited, capturing a maximum of 100 kpts at a speed of 500 kS/s shared between the two channels. Without some additional front end circuitry to protect the Pico, the input voltage is limited to 0-3.3 V. Neither the app nor the firmware is open source, and getting access to the second channel and removing ads requires a ~$3 in-app purchase. Even so, we can still think of plenty of practical uses for a ~$7 oscilloscope. If you do decide to add some front-end circuitry to change to voltage range, you can set them in the app, and switch between them by pulling certain GPIO pins high or low. The app has most of the basic oscilloscope features covered, continuous and single shot capture, adjustable trigger settings and a scalable waveform display.

Simple, cheap oscilloscopes like these have their place, but you start to understand why the “real” ones are so expensive when you see what goes into developing a high performance oscilloscope.

How Did I Live Without A Microscope?

June 26, 2021 by Elliot Williams 48 Comments

Get yourself a decent stereo inspection microscope, preferably optical. Something that can magnify from maybe 4x to 40x is fine, anything outside this range is icing on the cake. Some people claim they’re fine with a minimum of 10x, but if you go there, you’re going to need a reducing lens eventually. Either way, get one, and you’ll thank me.

How do I know this? I finally caved in and bought one about two years ago now, and while it’s not something I use daily, it’s something that I use at least once a month and for which there is simply no substitute.

This is Hackaday, so a lot of you will be thinking “inspection scope = fine-pitch soldering” and you’re not wrong. With clearance of 10 cm or more, and a slab of sacrificial optical glass (“neutral density filter”) to protect the optics from tarry flux fumes, a stereo scope at 4x makes even the fiddliest solder joints possible. Good lighting, and sharp tweezers are also a must, of course. That’s what got me in the door.

But that’s the half of it, or less. When my scope was new to me — it hasn’t been “new” since the late 1980s — we spent a whole rainy Sunday afternoon microscoping whatever would fit under the lens. Grains of salt, blades of grass, all manner of bugs living and otherwise, shells, skin, textiles. Everything is cooler under the microscope.

The event that triggered this article wasn’t my son’s school project this week to photograph dandelion seeds. Nope, today my wife found a bug in the basement; to the microscope! And with a very quick and unfortunately very positive identification, we now know that we have to strain all of our flour for bread beetles and pitch whichever bags they came in with. Hooray!

The inspection scope was intended for the soldering bench, but has found general use as an irreplaceable household tool. While I admittedly also intended to use it to lure my son into science, the real fight over scope time has been with my wife. And that’s why you want an optical scope instead of one that’s tethered to a monitor — as a general-purpose tool, portability is paramount. No menu diving, no power source, and anyone can just grab it and go.

Convinced? Ready to pull out your wallet? Microscopes are like cars. You can spend as much as you’d like on one, the cheapest will cause you nothing but pain and suffering, and the difference between the mid-range and high-end is full of diminishing returns. Buying used, especially if you can kick the metaphorical tires, can be a great bargain, and a high-end used scope will hold its value a lot better than a new budget model. Just around $200 is a sweet spot new and $300-$400 will get you the top of the line from yesteryear if you shop around. That’s not cheap, but if you’re the microscope type, it’s easily worth it. Trust me.

Can The Solenoid Engine Power A Car?

June 26, 2021 by Bryan Cockfield 12 Comments

[Emiel] aka [The Practical Engineer] makes all kinds of fun projects in his fully-featured shop, and one of his tangents has been building a series of solenoid engines. These engines mimic the function of an internal combustion engine, with each solenoid acting as a piston. The only problem with [Emiel]’s concept engines, though, was that he never actually put them into a vehicle to prove their effectiveness. This build finally proves that they can work at powering a vehicle.

The project starts with a new engine. [Emiel] chose a V4 design using four solenoids and an Arduino-based controller. After some trouble getting it to operate properly, he scavenged a small circuit board he built in his V8 solenoid engine to help with timing. With that installed, the solenoids click away and spin the crankshaft at a single constant speed. The vehicle itself was mostly 3D printed, with two aluminum tubes as support structures to mount the engine. Even the wheels were 3D printed with a special rubber coating applied to them. With a small drive train assembled, it’s off to the races for this tiny prototype.

While the small car doesn’t have steering and only goes at a constant speed, the proof of concept that these tiny electric engines actually work is a welcomed addition to [Emiel]’s collection of videos on these curious engines. Of course they’re not as efficient as driving the wheels directly with an electric motor, but we all know there’s no fun in that. If you haven’t seen his most intricate build, the V8 is certainly worth checking out, and also shows off the timing circuitry he repurposed for this car.

Continue reading “Can The Solenoid Engine Power A Car?” →

Random Numbers From A Smoke Detector

June 26, 2021 by Jenny List 21 Comments

The quest for truly random numbers is something to which scientists and engineers have devoted a lot of time and effort. The trick is to find an unpredictable source of naturally occurring noise that can be sampled, so they have looked towards noisy gas discharge tubes or semiconductor junctions, and radioactive decay. Noisy electrical circuits have appeared in these pages before as random number generators, but we’d be forgiven for thinking that radioactive decay might involve something a little less run-of-the-mill. In fact we all probably have just such a device in our houses, in the form of the ionisation chamber that’s part of most household smoke detectors. [Lukas Koch] has built a project that shows us just how this can be done.

A smoke detector of this type uses a metal shell to house a tiny sample of radioactive americium that emits alpha particles into the space between two electrodes. These ionise the air in that space, and the detectable effect on the space between the two electrodes is increased when ionised gasses from smoke are present. However it can also quite happily detect the ionisation from individual alpha particles, which means that it’s perfect as a source of random noise. A sensitive current amplifier requires significant shielding to avoid the device merely becoming a source of mains hum, and to that end he’s achieved a working breadboard prototype.

This is still a work in progress and though it has as yet no schematic he promises us that it will arrive in due course. It’s a project that’s definitely worth watching, because despite getting more up-close and personal than most of us have with radioactive components, it’s one we’re genuinely interested to see come to fruition.

Of course, we’ve seen smoke detectors in more detail before here at Hackaday.

PiNet — One Small Project Grows Unexpectedly

June 25, 2021 by Chris Lott 21 Comments

A few years ago, [Gregory Sanders] aka [Dr Gerg] had one simple wish in mind when he started what is now the PiNet project — to know whether his garage door was open or closed. Instead of searching out off-the-shelf solutions, he looked at the project as a learning opportunity. After picking up Python, he built a system from a Raspberry Pi, a 12V gel cell battery, and a power supply / charger circuit. Thus project Overhead Door (ohd) was complete (see the ohd GitHub repository) and [Dr Gerg] was done.

Or so he thought. After getting a swimming pool installed, he got the itch again, and started a new project called Pool Controls, because:

The controls for your average backyard in-ground pool are pathetic. I felt like I could do better with a Raspberry Pi, a relay board and some Python. And so I did, and frankly, it’s awesome.

Then he built his own weather station to replaced a commercial one which had died twice in as many years, followed by his own web-based UI framework. Next was the integration of an outdoor security camera system. And finally, although we don’t believe it’s really final, he ripped out the cloud-based controls from his shop air conditioner and added his own Raspberry Pi-based solution. All of these projects are available on his GitHub page.

[Dr Gerg]’s goal in posting all this work is not necessarily so people can duplicate it, although that is okay as well. Instead, he hopes that people will realize that they can build these types of projects on their own, perhaps leaning some things and picking up new skills along the way — have fun doing it. We like the way you think, [Dr Gerg]. Do you know of any small projects which grew and grew and took on a life of their own?

Some Of The Many Ways To Build AM Transmitters And Receivers

June 25, 2021 by Danie Conradie 10 Comments

AM radios are relatively simple devices, and building one is a good way to start exploring the world of radio communications. [GreatScott] does exactly this in the video after the break, building both a transmitter and receiver.

At the most basic level, AM radio works by generating a carrier wave with an oscillator, and then modulating the amplitude with an audio signal. Around these parts, the venerable 555 timer is always brought up whenever things get to oscillating; so you’ll no doubt be happy to see [GreatScott] decided to give it a shot for his first experiments, testing two popular 555 transmitter circuits. One uses the control voltage pin to input the audio signal, while the other uses the reset pin. The CV-pin version worked slightly better, but it was still just barely possible to distinguish a voice over a standard commercial AM/FM receiver.

The next attempt was with a XR2206 function generator kit, which worked quite well when combined with a simple microphone amplifier circuit. But this time the receiving side was swapped out, as [GreatScott] built a basic circuit around a TA7642 AM amplifier/demodulator IC, with only six passive components and a hand-wound coil.

There is no shortage of ways to build AM radios, and we’ve covered quite a few over the years. Off course a 555 timer can also be used in a receiver, and building transmitters using only discrete components is quite simple, as demonstrated by the 10-minute transmitter and single transistor transmitter.

Continue reading “Some Of The Many Ways To Build AM Transmitters And Receivers” →

A Custom Clock With LED Filament Hands

June 25, 2021 by Zach Zeman 13 Comments

LEDs have become so ubiquitous in our projects that just hearing that term probably conjures images of tiny illuminated domes in an array of single-spectrum colors. It’s easy to forget that these efficient sources of light come in a variety of form factors, including the retro-tacular filaments that [bitborked] used to make his beautiful analog LED wall clock.

Aside from its aesthetics, this timepiece features some great design. A custom PCB acts as a hub for all the LED filament spokes. The onboard brains come in the form of an ESP32, which means it can keep extremely accurate time via NTP. WS2811 LED controllers, which we’re so accustomed to seeing alongside RGB LEDs that they almost feel strange to see here, provide the 12 volts required for each filament and make individual addressing a breeze.

[bitborked] takes advantage of that addressability to display other animations in addition to the standard clock face. They also plan to implement MQTT for eventual alerts from other home automation devices. When it comes to just telling time, you can discern the individual “hands” by differences in their brightness, which sadly does not show up as well in video as it does in real life.

We would certainly be happy to have this clock on our walls, and we hope to eventually see more of its PCB designs. In the meantime, though, we can drool over a more digital take on the LED filament clock. Although, filaments are certainly not required to make a beautiful LED timekeeper.