A few years ago, there was a stir about a new fundamental component called a memristor. That wasn’t the first time a new component type was theorized though. In 1948 [Bernard Tellegen] postulated the gyrator. While you can’t buy one as a component, you can build one using other components. In fact, they are very necessary for some types of design. Put simply, a gyrator is a two-terminal device that inverts the current-voltage characteristic of an electrical component. Therefore, you can use a gyrator to convert a capacitor into an inductor or vice versa.
Keep in mind, the conversion is simply the electrical properties. Normally, current leads voltage in a capacitor and lags it in an inductor, and that’s what a gyrator changes. If you use a gyrator and a capacitor to make a virtual inductor, that inductor won’t magnetically couple to another inductor, real or simulated. There’s no magnetic field to do so. You also don’t get big voltage spikes caused by back EMF, which depending on your application could be a plus or a minus. But if you need an ungainly inductor in a circuit for its phase response, a gyrator may be just the ticket.
Continue reading “Gyrators: The Fifth Element”
Pick a lock, plug in a WiFi-enabled Raspberry Pi and that’s nearly all there is to it.
There’s more than that of course, but the wind farms that [Jason Staggs] and his fellow researchers at the University of Tulsa had permission to access were — alarmingly — devoid of security measures beyond a padlock or tumbler lock on the turbines’ server closet. Being that wind farms are generally in open fields away from watchful eyes, there is little indeed to deter a would-be attacker.
[Staggs] notes that a savvy intruder has the potential to shut down or cause considerable — and expensive — damage to entire farms without alerting their operators, usually needing access to only one turbine to do so. Once they’d entered the turbine’s innards, the team made good on their penetration test by plugging their Pi into the turbine’s programmable automation controller and circumventing the modest network security.
The team are presenting their findings from the five farms they accessed at the Black Hat security conference — manufacturers, company names, locations and etc. withheld for obvious reasons. One hopes that security measures are stepped up in the near future if wind power is to become an integral part of the power grid.
All this talk of hacking and wind reminds us of our favourite wind-powered wanderer: the Strandbeest!
A good robot is always welcome around here at Hackaday, and Hackaday.io user [igorfonseca83]’browser-controlled ‘bot s is no exception. Felines beware.
[igorfonseca83] — building on another project he’s involved in — used simple materials for the robot itself, but you could use just about anything. His goal for this build was to maximize accessibility in terms of components and construction using common tools.
An Arduino Uno gets two D/C motors a-driving using an H-bridge circuit — granting independent control the wheels — an ESP8266 enabling WiFi access, with power provided by a simple 5V USB power bank. [igorfonseca83] is using an Android smartphone to transmit audio and video data; though this was mostly for convenience on his part, a Raspberry Pi and camera module combo as another great option!
Continue reading “Stalk Your Cats With A Browser-Controlled Robot”