How To Get Started With The ESP32

ESP32 is the hottest new wireless chip out there, offering both WiFi and Bluetooth Low Energy radios rolled up with a dual-core 32-bit processor and packed with peripherals of every kind. We got some review sample dev boards, Adafruit and Seeed Studio had them in stock for a while, and AI-Thinker — the company that makes the most popular ESP8266 modules — is starting up full-scale production on October 1st. This means that some of you have the new hotness in your hands right now, and the rest of you aren’t going to have to wait more than a few more weeks.

As we said in our first-look review of the new chip, many things are in a state of flux on the software side, but the basic process of writing, compiling, and flashing code to the chip is going to remain stable. It’s time to start up some tutorials!

Continue reading “How To Get Started With The ESP32”

Homemade Capacitors Of A Mad Scientist

Once upon a time I was a real mad scientist. I was into non-conventional propulsion with the idea of somehow interacting with the quantum vacuum fluctuations, the zero point energy field. I was into it despite having only a vague understanding of what that was and without regard for how unlikely or impossible anyone said it was to interact with on a macro scale. But we all had to come from somewhere, and that was my introduction to the world of high voltages and homemade capacitors.

And along the way I made some pretty interesting, or different, capacitors which I’ll talk about here.

Large Wax Cylindrical Capacitor

As the photos show, this capacitor is fairly large, appearing like a thick chunk of paraffin wax sandwiched between two wood disks. Inside, the lead wires go to two aluminum flashing disks that are the capacitor plates spaced 2.5cm (1 inch) apart. But in between them the dielectric consists of seven more aluminum flashing disks separated by plain cotton sheets immersed in more paraffin wax. See, I told you these capacitors were different.

I won’t go into the reasoning behind the construction — it was all shot-in-the-dark ideas, backed by hope, unicorn hairs, and practically no theory. The interesting thing here was the experiment itself. It worked!

I sat the capacitor on top of a tall 4″ diameter ABS pipe which in turn sat on a digital scale on the floor. High voltage in the tens of kilovolts was put across the capacitor through thickly insulated wires. The power supply contained a flyback transformer and Cockcroft-Walton voltage multiplier at the HV side. As I dialed up the voltage, the scale showed a reducing weight. I had weight-loss!

But after a few hours of reversing polarities and flipping the capacitor the other way around and taking plenty of notes, I found the cause. The weight-loss happened only when the feed wires were oriented with the top one feeding downward as shown in the diagram, but there was no weight change when the top wire was oriented horizontally. I’d seen high voltage wires moving before and here it was again, producing what looked like weight-loss on the scale.

But that’s only one of the interesting capacitors I’ve made. After the break we get into gravitators, polysulfide and even barium titanate.

Continue reading “Homemade Capacitors Of A Mad Scientist”

The Fastest Rise Time In The West: Making A Truly Quick Pulse Edge

When we are taught about oscillators as newbie engineers, we are shown a variety of waveforms on an oscilloscope or in a textbook. This is a sine wave, they say, this is a sawtooth, this is a square wave, and so on. We’re taught to look at the lines on the screen as idealised, a square wave is truly square, and the transition from low to high voltage and back again is instantaneous.

In most cases this assumption is harmless. If we look into the subject a little deeper we learn that what seemed an instantaneous cliff-face is in fact a very steep slope, but when a circuit does its business in milliseconds there is usually no harm in ignoring a transition time measured in nanoseconds. The glue logic for your Arduino project can take its time.

Sometimes though, the rise time of a logic transition is important. The application that prompted this article was the measurement of oscilloscope bandwidth by looking at how quickly the ‘scope catches up with a pulse that exceeds its bandwidth, for example. When the instrument can happily measure the transition times of all your usual  pulse generators, something out of the ordinary is called for. So it’s worth taking a look at the rise times you’d expect from everyday circuitry, examining a few techniques for generating rise times that are much faster.
Continue reading “The Fastest Rise Time In The West: Making A Truly Quick Pulse Edge”

Lock Up Your Raspberry Pi With Google Authenticator

Raspberry Pi boards (or any of the many similar boards) are handy to leave at odd places to talk to the network and collect data, control things, or do whatever other tasks you need a tiny fanless computer to do. Of course, any time you have a computer on a network, you are inviting hackers (and not our kind of hackers) to break in.

We recently looked at how to tunnel ssh using a reverse proxy via Pagekite so you can connect to a Pi even through firewalls and at dynamic IP addresses. How do you stop a bad guy from trying to log in repeatedly until they have access? This can work on any Linux machine, but for this tutorial I’ll use Raspberry Pi as the example device. In all cases, knowing how to set up adequate ssh security is paramount for anything you drop onto a network.

Continue reading “Lock Up Your Raspberry Pi With Google Authenticator”

Creating A PCB In Everything: Eagle DRC And Gerber Files

For the next post in the Creating A PCB series, we’re going to continue our explorations of Eagle. In Part 1,  I went over how to create a part from scratch in Eagle. In Part 2, we used this part to create the small example board from the Introduction.

This time around I’ll be going over Design Rule Check (DRC) — or making sure your board house can actually fabricate what you’ve designed. I’ll also be covering the creation of Gerber files (so you can get the PCB fabbed anywhere you want), and putting real art into the silkscreen and soldermask layers of your boards.

The idea behind this series is to explore different EDA suites and PCB design tools by designing the same circuit in each. You can check out the rest of the posts in this series right here.

Continue reading “Creating A PCB In Everything: Eagle DRC And Gerber Files”

Distributed Censorship Or Extortion? The IoT Vs Brian Krebs

Now it’s official. The particular website that was hit by a record-breaking distributed denial of service (DDOS) attack that we covered a few days ago was that of white-hat security journalist [Brian Krebs]: Krebs on Security.

During the DDOS attack, his site got 600 Gigabits per second of traffic. It didn’t involve amplification or reflection attacks, but rather a distributed network of zombie domestic appliances: routers, IP webcams, and digital video recorders (DVRs). All they did was create HTTP requests for his site, but there were well in excess of 100,000 of these bots.

In the end, [Krebs’] ISP, Akamai, had to drop him. He was getting pro bono service from them to start with, and while they’ve defended him against DDOS attacks in the past, it was costing them too much to continue in this case. An Akamai exec estimates it would have cost them millions to continue defending, and [Brian] doesn’t blame them. But when Akamai dropped the shields, his hosting provider would get slammed. [Krebs] told Akamai to redirect his domain to localhost and then he went dark.

Continue reading “Distributed Censorship Or Extortion? The IoT Vs Brian Krebs”

Chemical Formulas 101

It seems like every other day we hear about some hacker, tinkerer, maker, coder or one of the many other Do-It-Yourself engineer types getting their hands into a complex field once reserved to only a select few. Costs have come down, enabling common everyday folks to equip themselves with 3D printers, laser cutters, CNC mills and a host of other once very expensive pieces of equipment. Getting PCB boards made is literally dirt cheap, and there are more inexpensive Linux single board computers than we can keep track of these days. Combining the lowering hardware costs with the ever increasing wealth of knowledge available on the internet creates a perfect environment for DIYers to push into ever more specific scientific fields.

One of these fields is biomedical research. In labs across the world, you’ll find a host of different machines used to study and create biological and chemical compounds. These machines include DNA and protein synthesizers, mass spectrometers, UV spectrometers, lyophilizers, liquid chromatography machines, fraction collectors… I could go on and on.

These machines are prohibitively expensive to the DIYer. But they don’t have to be. We have the ability to make these machines in our garages if we wanted to. So why aren’t we? One of the reasons we see very few biomedical hacks is because the chemistry knowledge needed to make and operate these machines is generally not in the typical DIYers toolbox. This is something that we believe needs to change, and we start today.

In this article, we’re going to go over how to convert basic chemical formulas, such as C9H804 (aspirin), into its molecular structure, and visa versa. Such knowledge might be elementary, but it is a requirement for anyone who wishes to get started in biomedical hacking, and a great starting point for the curious among us.

Continue reading “Chemical Formulas 101”