Know How...

Jul 3rd 2014

Know How... 100

RC Power Plant

RC Power Plant 101
Although the show is no longer in production, you can enjoy episodes from the TWiT Archives.

Ammonia-Powered Fuel Cells

* Ammonia-based Hydrogen-powered energy storage is on the way. * It's a relatively efficient and clean way to store power, since hydrogen is THE most abundant element in the universe and the output of a hydrogen fuel cell is energy and water. * Unfortunately, the storage and transport of hydrogen is tricky at best, downright DANGEOUS at worst. - Compressed liquid hydrogen has a LOT of energy within it in, and it just wants to BURST out of its containment vessel - This make transportation a logistical nighmare and filling stations are potential death traps. ** All of this makes a hydrogen economy very, very expensive The scientists at the UK's "Science and Technology Facilities Council" MAY have found a solution to the cost of transporting and storing hydrogen: DON'T TRANSPORT AND STORE HYDROGEN! * Instead, they've come up with a way to use ammonia as a way to create hydrogen on demand. * Ammonia is relatively harmless: stable, easy to store and transport, and non-explosive in pure form. Ammonia is just NH3 - one atom of nitrogen and three atoms of hydrogen. * You can use certain metals to crack ammonia, but those metals tend to be rare and very expensive. * The UK team figured out how to crack ammonia with two simultaneous chemical processes instead of the catalyst. They're being a little cagy about exactly what chemical processes they're using, but they've built a "Ammonia Decomposition Reactor" about the size of a 2-liter bottle that could convert enough ammonia into hydrogen to run a mid-size family car. However, we can make an educated guess as to how the process will work: * Using any source of electrical energy, (or a hear/pressure reactor) you SPLIT two molecules of water (H2O) into twomolecules of H2 and one molecule of O2 * You combine 3 molecules of H2 with 1 molecule of N2 in a high-pressure chamber containing a catalyst in an endothermic reaction that turns it into 2 molecules of Ammonia (NH3) * 3 x H2 + 1 x N2 = 2 x NH3 * You now have nice, easy to transport, liquid ammonia. When you need the hydrogen for your fuel cell, you run it through their decomposition reactor: * For every 2 molecules of Ammonia, you get 1 molecule of Nitrogen and 2 molecules of Hydrogen * The Nitrogen drifts harmlessly into the air * The H2 combines with O2 in the fuel cell to form H20 and energy.

Synology got Doged - So Hack, Many Malware. Wow

Earlier this year, owners of Synology "Network Attached Storage" boxes noticed that their NASs were sluggish, with abnormally high CPU usage. * After a little research, it was found that the boxes had been infected with malware that installed itself into a folder labeled "PWNED" * This malware has been using the processing power of a number of Synology boxes... * Synology boxes are actually quite powerful in their own right. Many of the SMB versions use a dual-core Intel ATOM CPU and have at least a Gigabyte of memory, so in parallel, they could provide a decent amount of CryptoCurrency mining power. * In fact, that power was enough to mine 500 million Dogecoins. -- The equivilant of $620k But that's not the story... * The vulnerability that was used by the malware to remotely execute code was originally found in mid-September of 2013. * Synology released a patch that closed the vulnerability in their Linux-based "Disk Station Manager" Operating SYstem on September 23rd... just a few days after discovery. They also made the patch part of their next major Operating System release It was only in February 2014 later that they started getting tickets from users complaining about the slugging performance * That means that tens of thousands of users and small businesses failed to update their boxes even though they would have been informed of the vulnerability and their boxes would have automatically downloaded the patch. SO DOWNLOAD AND PATCH YOUR BOXES!!!

RC Power Plant 101

Electric motors turn an induced current into mechanical motion. * In other words, turn on the power, and the shaft spins. For our purposes, there are two types of electric motors: * Brushed and Brushless This is what a basic brushed electric motor looks like: 1. A power source 2. An Armature that contains - A shaft - A tightly wound coil of wire - A commutator 3. The assembly into which the Armature is mounted, which will contain: - Brushes - A Rotating Mount - A permanent magnet. Here's how it works. 1. The battery provides current to the brushes 2. The brushes make contact with the commutator. 3. The commutator allows the current to flow through the wire loop. 4. Current flows through a loop of wire will create a magnetic field with a positive pole and a negative pole. -- That magnetic field will interact with the magnetic field of the permanent magnet which also has a positive pole and a negative pole. -- Like poles will repell, opposite poles will attract: The positive side of the charge coil will be pushed away from the positive side of the permanent magnet and drawn to the negative side of the permanent magnet. -- At the same time, the negative side of the charged coil will be pused away from the negative side of the permanent magnet and drawn to the positive side of the permanent magnet. *** Because of this, the shaft, on which the coil rests, will turn! However, if that was it, the shaft would turn, AT MOST 179 degrees before coming to a stop. -- Once the poles of the field and the permanent magnet are aligned, that would be it. -- In order to get continuous rotation of the shaft, you need a way to reverse the poles of the magnetic field on the armature. -- By reversing the poles at the right time, you can continously make the field be repelled and attracted to the fields in the permanent magnet without ever reaching balance -- In other words... you get continous rotation from your motor. The secret is the commutator. * In a brushed motor, the commutator is the part of the armature that is connected to the coil that makes the electromagnetic field AND that connects to the brushes on the assembly. The commutator has two jobs: 1. To transfer power from a fixed point to the armature 2. To reverse the polarity of the current flowing through the armature, and thereby reversing the polarity of the magnetic field. ** The commutator is attached to the armature - so it SPINS with the armature -- The plates of the commutator are positioned so that they will switch the current going thorugh the coil JUST after the coil aligns with the magnetic field of the permanent magnet -- Since the commutator is a single unit with the coil, it will MECHANICALLY switch the current as the shaft spins. Brushed DC motors Advantages 1. Low Initial Cost 2. Easier to control the motor speed (More power = more speed.) 3. REALLY good low-end torque: It starts with all the torque it will ever have, then it drops off as the motor spins faster. Disadvantages 1. The brushes will eventually wear out, which means higher maintenence 2. There will be an electrical arc every time the commutator switches the flow of current. That arc will slowly eat away at the commutator's surface A Brushless motor is very much like a brushed motor: - There is a power source - There is an Armature - There is shaft - There is a coil that generates an electrical field - There is a permanent magnet - There is a commutator that flips the current flowing through the coil and therefore flips the electromagnetic field. Where it differes is in what part of the motor moves. * In a brushed motor, the permanent magnet is stationary and the armature rotates, driven by the current flowing through the coil attached to the armature. * In a brushless motor, the armature is STATIC. The permanent magnet rotates around or within the armature, driven by the current flowing through the coil attached to the armature. ** In other words... In a brushed motor, the armature rotates. In a brushless motor, the permanent magnet rotates. The big difference is in the commutator: * A brushed motor uses a mechanical commutator. As the shaft turns, it MECHANICALLY turns the commutator, which changes it position relative to the brushes, which allows it to flip current polarity. * A brushless motor uses a SENSOR to determine the position of the shaft, and the current is flipped ELECTRONICALLY by a controller. Brushless Advantages 1. Longer life - No brushes means no brushes to wear down. 2. Less maintenence - It doesn't use a mechanical process to switch current through the coil, but an ELECTRIC controller that uses a sensor within the motor to know the position of the armature. 3. More efficient b/c there is no friction from the brushes 4. Decreases the amount of EMI generated by the motor Brushless Motor Disadvantage 1. More expensive than a Brushed Motor 2. More complicated 3. Slighly more prone to damage (because of the sensor) How does all of this work in a RC model? -- With an Electronic Speed Controller!!!! Last week we showed you how a RC transmitters/recievers and servos work. -- An Electronic speed controller takes the positioning information from the reciever and turns it into a level that determines how much current is going to be pushed into your electric motor.

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