Author: Al Williams

4349 Articles

Correlated Electron Memory… Coming Soon?

October 21, 2020 by 26 Comments

We often see press releases and announcements about the next big technology in batteries, memory, displays, capacitors, or any of a number of other things. Usually we are suspicious since we typically don’t see any of this new technology in the marketplace over any reasonable timescale. So when we read about correlated-electron memory Cerfe Labs, we had to wonder if it would be more of the same. IOur suspicions may be justified of course, but it is telling that the company is a spin-off from ARM, so that gives them some real-world credibility.

Correlated-electron RAM or CeRAM is the usual press release material. Nonvolatile, smaller than SRAM, and fast. It sounds as though it could replace the SRAM in PC caches, for example, and take up less die space on the CPU chip. The principle is a bit odd. When electrons are forced together in certain materials, the properties of the material can change. This Mott transition (named after the inventor [Neville Mott]) can take carbon-doped nickel oxide and switch it from its natural electrical insulating state to a conducting state and back again.

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Arduino And Wire Detects Metal

October 21, 2020 by 7 Comments

Our old math teacher famously said, “You have to take what you know and use it find what you don’t know.” The same holds true for a lot of microcontroller designs including [rgco’s] clever metal detector that uses very little other than an Arduino. The principle of operation is simple. An Arduino can measure time, a coil and a resistor will create a delay proportional to the circuit values, and metal around the coil will change the coil’s inductance. As the inductance changes, so does the delay and, thus, the Arduino can sense metal, as you can see in the video below.

The simple principle is also simple in practice. Besides the Arduino and the coil, there’s a single resistor. You want a small coil since larger coils won’t detect smaller objects. If you don’t want to wind your own coil, [rgco] suggests using a roll of hookup wire as long as the resistance is under 10 ohms.

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Learn IC Decapping

October 21, 2020 by 15 Comments

Decapsulating ICs used to be an exotic technique. (I should know, I did that professionally for one of the big IC vendors back in the 1980s.) These days, more and more people are learning to take apart ICs for a variety of reasons. If you are interested in doing it yourself, [Juan Carlos Jimenez] has a post you should read about using acid to remove epoxy from ICs.

[Juan Carlos] used several different techniques with varying degrees of success. Keep in mind, that using nitric acid is generally pretty nasty. You need safety equipment and be sure to plan for bad things to happen. Have eyewash ready because once you splash acid in your eye, it is too late to get that together.

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Thinking About Creating A Raspberry Pi Replacement?

October 20, 2020 by 66 Comments

If you’ve ever wanted to try your hand at creating a Raspberry Pi-like board for yourself, you should check out [Jay Carlson’s] review of 10 different Linux-capable SoCs. Back in the 1960s, a computer was multiple refrigerator-sized boxes with thousands of interconnections and building one from scratch was only a dream for most people. Then ICs came and put all the most important parts in a little relatively inexpensive IC package and homebrew computing became much more accessible. Systems on Chip (SoC) has carried that even further, making it easier than ever to create entire systems, like the Pi and its many competitors.

Only a few years ago, making an SoC was still a big project because the vendors often didn’t want to release documentation to the public. In addition, most of the parts use ball grid array (BGA) packaging. BGA parts can be hard to work with, and require a multilayer PC board. Sure, you can’t plug these into a typical solderless breadboard. But working with these relatively large BGAs isn’t that hard and multilayer boards are now comparatively cheap. [Jay] reports that he got cheap PCBs and used a hot plate to build each board, and has some sage advice on how to do it.

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Let KiCad And Python Make Your Coils

October 19, 2020 by 16 Comments

We like to pretend that our circuits are as perfect as our schematics. But in truth, PCB traces have unwanted resistance, capacitance, and inductance. On the other hand, that means you can use those traces to build components. For example, it isn’t uncommon to see a very small value current sense resistor be nothing more than a long PC board trace. Using PC layers for decoupling capacitance and creating precise transmission lines are other examples. [IndoorGeek] takes us through his process of creating coils on the PCB using KiCad. To help, he used a Python script that works out the circles, something KiCAD has trouble with.

The idea is simple. A coil of wire has inductance even if it is a flat copper trace on a PCB. In this case, the coils are more for the electromagnetic properties, but the same idea applies if you wanted to build tuned circuits. The project took inspiration from FlexAR, an open-source flexible PCB magnet.

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Does Your Phone Need A RAM Drive?

October 19, 2020 by 73 Comments

Phones used to be phones. Then we got cordless phones which were part phone and part radio. Then we got cell phones. But with smartphones, we have a phone that is both a radio and a computer. Tiny battery operated computers are typically a bit anemic, but as technology marches forward, those tiny computers grew to the point that they outpace desktop machines from a few years ago. That means more and more phones are incorporating technology we used to reserve for desktop computers and servers. Case in point: Xiaomi now has a smartphone that sports a RAM drive. Is this really necessary?

While people like to say you can never be too rich or too thin, memory can never be too big or too fast. Unfortunately, that’s always been a zero-sum game. Fast memory tends to be lower-density while large capacity memory tends to be slower. The fastest common memory is static RAM, but that requires a lot of area on a chip per bit and also consumes a lot of power. That’s why most computers and devices use dynamic RAM for main storage. Since each bit is little more than a capacitor, the density is good and power requirements are reasonable. The downside? Internally, the memory needs a rewrite when read or periodically before the tiny capacitors discharge.

Although dynamic RAM density is high, flash memory still serves as the “disk drive” for most phones. It is dense, cheap, and — unlike RAM — holds data with no power. The downside is the interface to it is cumbersome and relatively slow despite new standards to improve throughput. There’s virtually no way the type of flash memory used in a typical phone will ever match the access speeds you can get with RAM.

So, are our phones held back by the speed of the flash? Are they calling out for a new paradigm that taps the speed of RAM whenever possible? Let’s unpack this issue.

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Free P2P VPN

October 18, 2020 by 34 Comments

People use a VPN — virtual private network — for a lot of reasons. However, for many people it is synonymous with hiding your network traffic, one thing that VPN can do. FreePN is a relatively new open source project that aims to build a free peer-to-peer VPN network. Like TOR, it is decentralized.

Right now, you can download for Ubuntu and Gentoo. There is a way to ask for early access for Debian, Fedora, and Arch. Windows, iOS, MacOS, and Android versions are promised for the future.

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