Abstracting Transistors Into High-level Design

Although it’s not the best way of understanding computers, most people tend to imagine electronic devices as black boxes filled with magic and blue smoke. Even microcontrollers, the most fundamental means of computation, are treated like little black plastic centipedes with metal legs. In a series of blog posts, [Andrew Gibiansky] is tearing down the walls of obfuscation and illuminating the world of transistors, gates, and FPGAs.

The first blog post goes over the idea of electronic circuits as a waterfall; a positive voltage is a reservoir on a mountain top and ground is sea level. This idea is extended to the lowly transistor acting as an electronic switch, able to turn a circuit on and off.

Continuing on to logic gates, [Andrew] covers the NOT, AND, and OR gates before moving on the flip-flops and SRAM. These can, of course, be modeled in Verilog and VHDL – programming languages that abstract the world of transistors and gates into a much more human-readable form.

[Andrew] is far from done with his series of blog posts, but judging from his work so far it seems to be a great resource for untangling the obtuse concepts of gates and memory into the coherent design of a computer.

Automated Resistor Sorter Puts Them Into Small Plastic Tubes

This one might be an oldie, but it’s certainly a goodie.

Way back in 2005, [David] and [Charles] needed a project for one of their engineering courses. With so many loose resistors scattered over the lab, they decided to build an automated resistor sorter (PDF warning) to separate these resistors and put resistors of the same value together in the same bin.

The electrical and programming portion of this build is relatively simple – just a PIC microcontroller reading the value of a resistor. The mechanical portion of this build is where it really shines. Resistors are sorted when they pass through small plastic tubes mounted to a wooden frame.

There are several levels of these tubes in [David] and [Charles]’ sorter that move back and forth. The process of actually sorting these resistors is a lot like going down a binary tree; at each level, the tube can go right or left with the help of a solenoid moving that level of the frame back or forth.

[David] and [Charles]’ project wasn’t entirely complete by the end of the class; to do so would require  8 levels and 128 different tubes on the bottom layer. Still, it worked as a proof of concept. We just wish there was a video of this machine in action.

Tip ‘o the hat to [Alexander] for finding this one and sending it in.

Outlet Charging Station Retrofitted With The Guts Of A WiFi Router

While wandering around the aisles of his local electronics store this Westinghouse USB charging station caught [James’] eye. He sized it up and realized it would make the perfect enclosure for a small WiFi router. And so began his project to turn a TP-Link TL-WR703N into a DIY Pwn Plug.

The basic idea is to include hidden capabilities in an otherwise normal-looking device. For instance, take a look at this ridiculously overpriced power strip that also happens to spy on your activities. It doesn’t sound like [James] has any black hat activities planned, but just wanted an interesting application for the router.

He removed the original circuit board from the charging station to make room for his own internals. He inserted a cellphone charger to power the router, then desoldered the USB ports and RJ-45 connector for the circuit board to be positioned in the openings of the case. He even included a headphone jack that breaks out the serial port. There’s a lot of new stuff packed into there, but all of the original features of the charging station remain intact.

More Continuous Wave Radar Fun

[Gregory Charvat] continues to have a great time testing out radar systems. He and a friend have pointed the radar out the garage door and are using it to see who can reach a high running velocity.

The last time we looked in on [Greg’s] work he had acquired an old police radar unit and wired it up to use with a laptop. The hardware he’s working with now is a lot more bulky and we don’t think it will be hitting the road with him anytime soon (although it is on wheels). The video after the break starts off which an overview of the test system which is mounted in a waist-high rack. He illustrates how Labview is monitoring the radar inputs and then moves on to show off the hardware which is actually harvesting the data. The box is quite versatile, able to run five different systems and includes a slew of different connector types.

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[Jeri] Uses Light Bulbs In An Oscillator

Way back when [Ms Ellsworth] was a kid, she kept seeing the same circuit over and over again in her various op-amp books. It was a Wien bridge oscillator, a small circuit that outputs a sine wave with the help of a light bulb. Now that [Jeri] is much wiser, she decided to play around with this strange oscillator and found it’s actually pretty impressive for, you know, a light bulb.

The interesting portion of the Wien bridge is the gain portion of the circuit. It’s just a simple resistor divider, with a light bulb thrown in on one of its legs. When the current increases, this causes the light bulb to warm up (not enough to glow, though). When the temperature increases, the resistance in the light bulb increases, making the oscillator reach an equilibrium.

It’s a clever setup, but what about swapping out a resistor in place of the light bulb? In the video, [Jeri] tries just that, and it’s a mess. Where the light bulb circuit is amazingly stable with very, very low distortion, the resistor circuit looks like a disaster on the scope with harmonics everywhere.

A very cool build that would be perfect for an audio synth, but as [Jeri] says in her YouTube comments, “This doesn’t have enough distortion for indie bands.”

Continue reading “[Jeri] Uses Light Bulbs In An Oscillator”

Building A Thermal Imaging Sensor From Scratch

[youtube=http://www.youtube.com/watch?v=pIb1scnD67o&w=470]

[Rob] lives in a 100-year-old house, and with these antique lath and plaster walls and old window frames comes a terrible amount of drafts. The usual way to combat this energy inefficiency is with a thermal imaging camera, a device that overlays the temperature of an object with a video image. These cameras are hideously expensive so [Rob] did what any of us would do and built his own.

The build centers around a Melexis MLX90620 far infrared thermopile that can be had for about $80. Basically, this sensor is a very, very low resolution camera (16×4 pixels) that senses heat instead of light. By sticking this sensor on a breadboard with an Arduino Mini and WiFly network adapter, [Rob] is able to pull the data down from the IR sensor to his iPhone and overlay it on the feed from the camera.

The result, as seen in the video above, is a low-resolution but still very useful thermal imaging camera, perfect for looking for cold drafts in an old house or tracking down [Arnie] just like a Predator.

Tip ‘o the hat to [Ronald] for sending this one in.

Netduino Gets A Huge Upgrade

The Netduino, a dev board built around the .NET Micro framework with the goal of being compatible with Arduino shields just got a huge upgrade.

The new Netduino Plus 2 features an upgraded STM32 ARM Cortex-M4 uC running at 168 MHz, improving on the original Netduino’s ARM7 running at 47 MHz. In addition to some more processing power, the STM32-based microcontroller has twice the RAM and six times as much Flash memory. Also, Ethernet (10Mbps), a MicroSD card port, and of course compatibility with all Arduino shields – including the new Arduino ‘Revision C’ boards for the Leonardo – remains intact.

In keeping with the design goals of the Netduino, the new board uses the .NET Micro Framework running under Windows. It looks like OS X and Linux users won’t be left out in the cold for long, though; there’s a project to port the .NET Micro stuff over to Mono.

Tip ‘o the hat to [Jason] for sending this one in.