Recycle LCDs Into LEDs

July 21, 2018 by Al Williams 12 Comments

We always find it funny when we see ads for modern LED TVs. These TVs don’t use LEDs to show the picture. They are nothing more than LCD screens with LED backlighting instead of cold cathode fluorescent lamps. [Akshaylals] had a few LCD laptop and phone panels that were defunct and decided to recycle them to get to the LEDs within.

Most panels are lit from one or two edges with a bar of LEDs. You only have to peel off some tape and plastic. If you wonder what all those plastic sheets do, see the [Engineer Guy’s] video, below.

Continue reading “Recycle LCDs Into LEDs” →

Old Phone, New Remote Switch

July 21, 2018 by Jenny List 38 Comments

With mobile phones now ubiquitous for the masses in much of the world for over two decades, something a lot of readers will be familiar with is a drawer full of their past devices. Alongside the older smartphone you’ll have a couple of feature phones, and probably at the bottom a Nokia candybar or a Motorola flip phone. There have been various attempts over the years to make use of the computing power the more recent ones contain through using their smartphone operating systems, but the older devices remain relatively useless.

[Vishwasnavada] has a neat plan though, using an ancient phone as a remote trigger device, by interfacing it with an Arduino. There are many ways this could be achieved depending on the model of the phone in question, but one thing common to nearly all devices is a vibration motor. Removing the motor and taking its power line to a GPIO allows the Arduino to sense when the phone is ringing. The idea then is that a call can be placed to the phone which is not picked up, but because it triggers the vibration motor it can be used to make the microcontroller do something remotely. A hack with limited capabilities then, but one that is cheap and simple, uses a recycled device, and should work almost anywhere populated on the planet given the global reach of 2G networks.

This isn’t the first respin of a classic Nokia we’ve brought you, they will also talk data.

Wire Wound Resistors On Your Own

July 21, 2018 by Al Williams 17 Comments

In all kinds of engineering, we build on abstractions in a kind of inverted pyramid. Lots of people can, for example, design a system using ready-made building blocks on printed circuit boards. Fewer people can do the same design using ICs. Fewer still can design with components. But who designs the components? Even fewer people. Then there are the people designing the constituent elements of those components. [Learnelectronics] wanted to break one of those abstraction layers so he shows how to make your own wire-wound resistors.

Wire-wound resistors are often used when you need resistance with a higher power dissipation than a common film or composition resistor. Using nichrome wire makes this more practical since a meter of it has nearly 20 ohms of resistance. A regular wire has much less resistance. The video shows a drill winding a coil of wire neatly, but this also highlights one of the problems with wire wound resistors.

Continue reading “Wire Wound Resistors On Your Own” →

A Caterpillar Drive That Actually Looks Like A Caterpillar

July 21, 2018 by Brian Benchoff 39 Comments

[Tom Clancy]’s The Hunt For Red October is a riveting tale of a high-level Soviet defector, a cunning young intelligence analyst, a chase across the North Atlantic, and a new submarine powered by a secret stealth ‘caterpillar’ drive. Of course there weren’t a whole lot of technical details in the book, but the basic idea of this propulsion system was a magnetohydrodynamic drive. Put salt water in a tube, wrap a coil of wire around the tube, run some current through the wire, and the water spits out the back. Yes, this is a real propulsion system, and there was a prototype ferry in Japan that used the technology, but really the whole idea of a caterpillar drive is just a weird footnote in the history of propulsion.

This project for the Hackaday Prize is probably the closest we’re going to see to a caterpillar drive, and it can do it on a small remote-controlled boat. Instead of forcing water out of the back of a tube with the help of magic pixies, it’s doing it with a piston. It’s a drive for a solar boat race, and if you look at the cutaway view, it does, indeed, look like a caterpillar.

Instead of pushing water through a tube by pushing water through a magnetic field, this drive system is something like a linear motor, moving a piston back and forth. The piston contains a valve, and when the piston moves one way, it sucks water in. When the piston moves in the opposite direction, it pushes water out.

The goal of this project is to compete against other solar powered remote-controlled boats. Of course, most of the other boats are using a DC motor and a propeller. This is a weird one, though, and we’re very interested in seeing how the production version will work.

Hacking A Very Special 486

July 21, 2018 by Jenny List 23 Comments

It’s fair to say that Moore’s Law is not delivering on its promise of advancing semiconductor capabilities as fast as it used to, as the limits of current fabrication techniques are being met. Where this is being written for example there are two laptops, one from the last year and one that is 11 years old, and while the new one is undeniably faster it has not overtaken the other by as much as a ten year gap between 1990s machines would have revealed.

So with older laptops being still so relatively quick, what possible attraction could there be for working on a machine from the 1990s, when the Moore’s Law curve was steeper? It’s something [Jim W] is doing, with his HP Internet Advisor (J2522B), and when you see the machine in question perhaps you’ll understand why. The J2522B is a laptop, but it’s no ordinary ’90s road warrior’s status symbol. This 486-powered beast is a piece of test equipment, specifically one for examining Ethernet ports, thus it’s built like a tank and is mains powered only. It boasts a 486DX4, 16 MB of memory, a then-colossal 1.3 GB hard drive, and an ISA Fast Ethernet card. Oh, and WIndows 95, which with a couple of decades’ hindsight seems an amusing choice to power a piece of security test equipment. Impressive specs for the day, but the $20,000 price tag would still have been steep compared to a comparable laptop.

[Jim]’s machine is destined for classic gaming, though with only the little HP pop-out mouse you saw on their Omnibook range at the time, he needed a PS/2 port. Some chipset hunting found that, but at the cost of accidentally frying a MOSFET when a screen connector was incorrectly re-inserted. We’re then treated to a guide to substituting older MOSFETs with modern parts, useful in itself, but followed by a marvelous piece of bodge work as an SOIC-8 part is placed on a DPAK footprint.

This is an interesting series of posts, partly from a retro angle as they deal with an interesting machine, but also from a hacking angle as he’s getting closer to the vintage PC hardware than most of us to. Keep an eye on it, there is sure to be more in the pipeline.

Measuring Web Latency In The Browser

July 21, 2018 by Tom Nardi 8 Comments

We’ll go out on a limb and assume that anyone reading these words is probably familiar with the classic ping command. Depending on which operating system you worship the options might be slightly different, but every variation of this simple tool does the same thing: send an ICMP echo request and wait for a response. How long it takes to get a response from the target, if it gets one at all, is shown to the user. This if often the very first step to diagnosing network connectivity issues; if this doesn’t work, there’s an excellent chance the line is dead.

But in the modern web-centric view of networking, ping might not give us the whole picture. But nature it doesn’t take into account things like DNS lookups, and it certainly doesn’t help you determine what (if any) services the target has available to you. Accordingly, [Liu Zhiyong] has come up with a tool he calls “pingms”, which allows you to check web server latency right from your browser.

Rather than relying on ICMP, pingms performs a more realistic test. It takes the list of targets from the file “targets.js” and connects to each one over HTTP. How does it work? The code [Liu] has come up with will take each target domain name, append a random number to create a gibberish filename, and then calculate how long it takes to get a response when trying to download the file. Obviously it’s going to be getting a 404 response from the web server, but the important thing is simply that it gets the response.

With this data, [Liu] has come up with a simplistic but very slick interface which shows the user the collected data with easy to understand color-coded graphs. As interesting as it is to see how long it takes your favorite web sites or service providers to wake up and start talking, watching the colored bars hop up and down the list to sort themselves is easily our favorite part of pingms.

[Liu] has released pingms under the GPLv3 license, so if you’re looking to utilize the software for your own purposes you just need to provide a list of test targets. If you need to perform low-level diagnostics, check out this handy network tester you can build for cheap.