Custom PLCs for Automation Industries

For many years, factories have used PLCs for automated control over industrial equipment. These systems are usually expensive, proprietary, and generally incapable of being reprogrammed. [Oliver], an engineering student in Ireland created a system for factories to develop their own application-specific PLCs as a final project for Automation Engineering.

In-house PLC creation has many benefits for manufacturers, not the least of which is the opportunity for customization. Making your own PLCs also means no licensing fees and total control over equipment automation. This system is a complete setup including an HMI interface with touchscreen input and a SCADA system for remotely controlling various pieces equipment of equipment from a laptop.

[Oliver] built a metal frame out of industrial-grade strut channel to house an XP machine, two monitors, and the beautifully breadboarded PLC design station. It’s based around a PIC16F887 and includes rugged features expected of a system that never goes into sleep mode, like eight channels of opto-isolation. [Oliver] also developed an environment for engineers to easily program their custom PLCs through a simple HMI interface and ladder logic.

Broken Bread Maker Rises Again, Drives Tool-Sharpening Turntable

Poor [makendo] had seven broken bread makers lying around, all with failed paddle drivers. Since they also all have big motors and other useful parts in them, he decided to turn one of them into a powered tool-sharpening turntable.

First, [makendo]  salvaged the motor, the gear, and the thick circular glass window from one of the bread makers. He cut a platter from plywood the size of the glass window, chamfering the edge to fit the gear. Next, he built a housing from scrap plywood, separating the motor from the platter with a crosspiece to keep the motor free from dust. A large magnet on a hinge collects metal powder from the system quite effectively. The sharpener spins at about 200RPM: fast enough to do the job and slow enough not to get hot.

According to [makendo], the sharpener restores bevels nicely but doesn’t make edges”scary sharp”. To that end, he used a toaster oven door as a base for a series of micro-abrasive grits of sandpaper as a finishing rig. In order to sharpen his chisels uniformly, he made a jig to hold them firmly in place against either the powered turntable or the fine sandpapers.

[Thanks for the tip, Scott]


Dirt Cheap Motor Balancing and Vibration Analysis

Ever the enterprising hacker and discerning tool aficionado, [Chris] knows the importance of “feel”. As a general rule, cheap tools will shake in your hand because the motors are not well-balanced. He wanted a way to quantify said feel on the cheap, and made a video describing how he was able to determine the damping of a drill using a few items most people have lying around: an earbud, a neodymium magnet, scrap steel, and Audacity.

He’s affixed the body of the drill to a cantilevered piece of scrap steel secured in a vise. The neodymium magnet stuck to the steel interrupts the magnetic field in the earbud, which is held in place with a third hand tool. [Chris] taped the drill’s trigger down and controls its speed a variac. First, [Chris] finds the natural frequency of the system using Audacity’s plot spectrum, and then gets the drill to run at the same speed to induce wobbling at different nodes. As he explains, one need not even use software to show the vibration nodes—a laser attached to the system and aimed at a phosphorescent target will plot the sine wave.

Just for fun, he severely unbalances the drill to find the frequencies at which the system will shake itself apart. Check it out after the break.

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EVA: What’s on Telly for the Visually Impaired

[chewabledrapery] has certainly used his Raspberry Pi for good. His girlfriend’s grandfather is growing more visually impaired as time goes on. He likes to watch telly, but has trouble reading the on-screen information about the channel and programming. To that end, [chewabledrapery] has built an electronic voice assistant called EVA, who fetches the telly schedule from a web service and reads it aloud in her lovely voice that comes courtesy of Google Translate’s TTS function.

Under EVA’s hood is a Raspberry Pi. A USB hub powers the Pi and holds a small USB soundcard, a Wi-Fi dongle, and a USB daughterboard that the controller plugs into. The daughterboard is from a USB keyboard, which makes another appearance in the awesome controller. It’s made of a joystick and two arcade buttons that use the USB keyboard’s controller to interact with Python scripts.

[chewabledrapery]’s scripts make formatted requests to a web service called atlas, which returns JSON objects with the TV schedule and content descriptions. EVA then turns to Google Translate, speaking the formatted text through a small amplifier and salvaged PC speaker. In order to minimize the number of web calls, some of EVA’s frequent musings are stored locally. A full tour of EVA is after the break.

We love to see hacks that help people. Remember this RFID audio book reader?

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Retrotechtacular: Crystals Go to War

More than one of our readers suggested we highlight this beautifully-shot process documentary about the laborious and precise manufacturing of piezoelectric quartz crystals in the early 1940s. Just a few years later, Bell Labs would perfect a method of growing synthetic crystals, sending droves of brave men and daintily-handed women from the Reeves Sound Laboratories to the unemployment line.

Early radio equipment relied upon tuned or L-C circuits for clocking. These were prone to drift by a few kHz, which prompted the use of crystal oscillators for stable frequencies in the 1920s. The lives of our armed forces and those of our WWII allies depended on reliable communication equipment, so the crystal oscillators they used were top shelf, produced by hand from Brazilian crust.

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Retrotechtacular: Step Up and Get Your Transformer Training

Whether you’re just getting into electronics or could use a refresher on some component or phenomenon, it’s hard to beat the training films made by the U.S. military. This 1965 overview of transformers and their operations is another great example of clear and concise instruction, this time by the Air Force.

It opens to a sweeping orchestral piece reminiscent of the I Love Lucy theme. A lone instructor introduces the idea of transformers, their principles, and their applications in what seems to be a single take. We learn that transformers can increase or reduce voltage, stepping it up or down through electromagnetic induction. He moves on to describe transformer action, whereby voltages are increased or decreased depending on the ratio of turns in the primary winding to that of the secondary winding.

He explains that transformer action does not change the energy involved. Whether the turns ratio is 1:2 or 1:10, power remains the same from the primary to the secondary winding. After touching briefly on the coefficient of coupling, he discusses four types of transformers: power, audio, RF, and autotransformers.

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Retrotechtacular: Teleprinter Tour, Teardown

This week, we’re taking the wayback machine to 1940 for an informative, fast-paced look at the teleprinter. At the telegram office’s counter, [Mary] recites her well-wishes to the clerk. He fills out a form, stuffs it into a small canister, and sends it whooshing through a tube down to the instrument room. Here, an operator types up the telegram on a fascinating electro-mechanical device known as a teleprinter, and [Mary]’s congratulatory offering is transmitted over wires to her friend’s local telegraph office hundreds of miles away.

We see that the teleprinter is a transceiver that mechanically converts the operator’s key presses into a 5-digit binary code. For example, ‘y’ = 10101. This code is then transmitted as electrical pulses to teleprinters at distant offices, where they are translated back into alphanumerical data. This film does a fantastic job of explaining the methods by which all of this occurs and does so with an abstracted, color-coded model of the teleprinter’s innards.

The conversion from operator input to binary output is explained first, followed by the mechanical translation back to text on the receiving end. Here, it is typed out on a skinny paper tape by the type wheel shown above. Telegraphists in the receiving offices of this era cut and pasted the tape on a blank telegram in the form of meaningful prose. Finally, it is delivered to its intended recipient by a cheeky lad on a motorbike.

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