Building Triodes With Blinker Fluid

January 9, 2016 by 67 Comments

The triode is one of the simplest kinds of vacuum tubes. Inside its evacuated glass envelope, the triode really is just a few bits of wire and metal. Triodes are able to amplify signals simply by heating a cathode, and modulating the flow of electrons to the anode with a control grid. Triodes, and their semiconductor cousin the transistor, are the basis of everything we do with electricity.

Because triodes are so fantastically simple, they’re the parts most commonly crafted by the homebrew tube artisans of today. You don’t need a glass blowing lathe to make the most basic vacuum tube, though: [Marcel] built one from the light bulb used in a car’s tail light.

The light bulb in your car’s tail light has two filaments inside: one for the normal tail light, and a second one that comes on when you brake. By burning out the dimmer filament, [Marcel] created the simplest vacuum tube device possible. In his first experiment, he turned this broken light bulb into a diode by using the disconnected filament as the anode, and the burning filament as the cathode. [Marcel] attached a 1M resistor and measured 30mV across it. It was a diode, with 30μA flowing.

The triode is just a diode with a grid, but [Marcel] couldn’t open up the light bulb to install a piece of metal. Instead, he wrapped the bulb in aluminum foil. After many attempts, [Marcel] eventually got some amplification out of his light bulb triode.

The performance is terrible – this light bulb triode actually has an “amplification” of -108dB, making it a complete waste of energy and time. It does demonstrate the concept though, even though the grid isn’t between the anode and cathode, and this light bulb is probably filled with argon. It does work in the most perverse sense of the word,  and makes for a very interesting build.

Video Gives You The Basics Of DIY Rotary Encoders

January 8, 2016 by 45 Comments

Is it really possible to build a rotary encoder out of a flattened tin can and a couple of photodetectors? Sure it’s possible, but what kind of resolution are you going to get from such a contraption? Is there any way that you’d be able to put them to work in a DIY project like a CNC router? If you pay attention to the basics then the answer is yes, and [HomoFaciens] wants to prove that to you with this detailed video on homebrew encoder design.

Faithful Hackaday readers will no doubt recognize [HomoFaciens] from a number of prior appearances on these pages, including this recent hardware store CNC router build. When we first ran across his builds, we admit a snicker or two was had at the homemade encoders, but if you watch the results he manages to get out of his builds, you quickly realize how much you can accomplish with very little. The video is a primer on encoder design, walking you through the basics of sensing rotation with phototransistors, and how a pair of detectors is needed to determine the direction of rotation. He also discusses the relative merits of the number of teeth in the chopper; turns out more isn’t necessarily better. And in the end he manages to turn a car wiper motor into a high-torque servo, which could be a handy trick to have filed away.

Continue reading “Video Gives You The Basics Of DIY Rotary Encoders” →

Internet Of Things In Five Minutes

January 8, 2016 by 22 Comments

If you’re looking for the quickest way to go from zero to voice-controlled home automation system, you should spend five minutes checking out [Hari Wiguna]’s project on Hackaday.io where he connects up IoT gadgets and services into a functioning lightswitch. (Video below the break.)

6166971452133983621[Hari] demonstrates how to set up a complex chain: Amazon Echo to IFTTT to Adafruit.io as a data broker, which is then polled by an ESP8266 unit in his home that controls his X10 setup. (Pshwew.) But each step along the way is designed to be nearly plug-and-play, so it’s really a lot like clicking Lego blocks together. [Hari]’s video is a nice overview.

There’s only one catch if you’re going to replicate this yourself: the X10 system that’s used for the last mile. Unless you have one of these setups already, you’re on your own for controlling the outlets that turn the lights on and off. For price and hackability, we suggest the common 433MHz wireless outlet switches and pairing them with cheap 433MHz transmitters, available at eBay for around $1. We’ve seen a lot of hacks of these systems — they’re quite common both in the US and Europe.

We’ve also covered [Hari]’s projects before: both his self-learning TV remote and a sweet Halloween hack. His video production skills are excellent. We’re in awe of how much info he crams into his YouTube videos.

Zedboard Multiport Ethernet

January 8, 2016 by 9 Comments

The Zedboard uses Xilinx’s Zynq, which is a combination ARM CPU and FPGA. [Jeff Johnson] recently posted an excellent two-part tutorial covering using a Zedboard with multiple Ethernet ports. The lwIP (light-weight Internet Protocol) stack takes care of the software end.

Vivado is Xilinx’s software for configuring the Zynq (among other chips), and the tutorial shows you how to use it. The Ethernet PHY is an FPGA Mezzanine Card (FMC) with four ports that is commercially available. The project uses VHDL, but there is no VHDL coding involved, just the use of canned components.

The real issue when using an FPGA and a CPU is the interface between the processor and the FPGA circuitry. In this case, the ARM standard AXI bus does this task, and the Ethernet component properly interfaces to that bus. The IP application in the second part of the post is an echo server.

We’ve seen the Zynq used in flying machines and also in a music synthesizer. Although this project doesn’t use any Verilog or VHDL that you create, it is still a great example of configuring using Vivado and using common components in a design.

Baby Saved By Doctors Using Google Cardboard After 3D Printer Fails

January 8, 2016 by 64 Comments

It’s a parent’s worst nightmare. Doctors tell you that your baby is sick and there’s nothing they can do. Luckily though, a combination of hacks led to a happy ending for [Teegan Lexcen] and her family.

When [Cassidy and Chad Lexcen]’s twin daughters were born in August, smaller twin [Teegan] was clearly in trouble. Diagnostics at the Minnesota hospital confirmed that she had been born with only one lung and half a heart. [Teegan]’s parents went home and prepared for the inevitable, but after two months, she was still alive. [Cassidy and Chad] started looking for second opinions, and after a few false starts, [Teegan]’s scans ended up at Miami’s Nicklaus Children’s Hospital, where the cardiac team looked them over. They ordered a 3D print of the scans to help visualize possible surgical fixes, but the 3D printer broke.

Not giving up, they threw [Teegan]’s scans into Sketchfab, slapped an iPhone into a Google Cardboard that one of the docs had been playing with in his office, and were able to see a surgical solution to [Teegan]’s problem. Not only was Cardboard able to make up for the wonky 3D printer, it was able to surpass it – the 3D print would only have been the of the heart, while the VR images showed the heart in the context of the rest of the thoracic cavity.[Dr. Redmond Burke] and his team were able to fix [Teegan]’s heart in early December, and she should be able to go home in a few weeks to join her sister [Riley] and make a complete recovery.

We love the effect that creative use of technology can have on our lives. We’ve already seen a husband using the same Sketchfab tool to find a neurologist that remove his wife’s brain tumor. Now this is a great example of doctors doing what it takes to better leverage the data at their disposal to make important decisions.

Ode To The TL431, And A LiFePO4 Battery Charger

January 8, 2016 by 85 Comments

Nerd Ralph loves cheap and dirty hacks, and for that we applaud him. His latest endeavor is a LiFePO4 battery charger that he made out of parts he had on hand for under $0.50 US. (Although we think he really made it for the fun of making it.)

The circuit is centered around a TL431 programmable shunt regulator, which is an awesome and underrated chip in its own right. If you don’t know the TL431 (aka LM431), you owe it to yourself to fetch the datasheet and pick up a couple with your next electronics part order. In fact, it’s such a great chip, we can’t resist telling you about it for a minute.

Continue reading “Ode To The TL431, And A LiFePO4 Battery Charger” →

CES: Self-Flying Drone Cars

January 8, 2016 by 36 Comments

CES, the Consumer Electronics Show, is in full swing. Just for a second, let’s take a step back and assess the zeitgeist of the tech literati. Drones – or quadcopters, or UAVs, or UASes, whatever you call them – are huge. Self-driving cars are the next big thing. Flying cars have always been popular. On the technical side of things, batteries are getting really good, and China is slowly figuring out aerospace technologies. What could this possibly mean for CES? Self-flying drone cars.

The Ehang 184 is billed as the first autonomous drone that can carry a human. The idea is a flying version of the self-driving cars that are just over the horizon: hop in a whirring deathtrap, set your destination, and soar through the air above the plebs that just aren’t as special as you.

While the Ehang 184 sounds like a horrendously ill-conceived Indiegogo campaign, the company has released some specs for their self-flying drone car. It’s an octocopter, powered by eight 106kW brushless motors. Flight time is about 23 minutes, with a range of about 10 miles. The empty weight of the aircraft is 200 kg (440 lbs), with a maximum payload of 100 kg (220 lbs). This puts the MTOW of the Ehang 184 at 660 lbs, far below the 1,320 lbs cutoff for light sport aircraft as defined by the FAA, but far more than the definition of an ultralight – 254 lbs empty weight.

In any event, it’s a purely academic matter to consider how such a vehicle would be licensed by the FAA or any other civil aviation administration. It’s already illegal to test in the US, authorities haven’t really caught up to the idea of fixed-wing aircraft powered by batteries, and the idea of a legal autonomous aircraft carrying a passenger is ludicrous.

Is the Ehang 184 a real product? There is no price, and no conceivable way any government would allow an autonomous aircraft fly with someone inside it. It is, however, a perfect embodiment of the insanity of CES.