Le moteur à courant continu - Tuto Arduino - Le blog d'Eskimon Nul doute que vous connaissez l’existence des moteurs car il en existe toute une panoplie ! Le premier qui vous viendra certainement à l’esprit sera le moteur de voiture, ou peut-être celui présent dans une perceuse électrique. Voilà deux exemples d’objets dans lesquels on peut trouver un moteur. Bien entendu, ces deux moteurs sont de type différent, il serait en effet peu probable de faire avancer votre voiture avec un moteur de perceuse électrique… et puis l’utilisation d’une perceuse intégrant un moteur de voiture de plusieurs centaines de kilos serait fastidieuse . Sommaire Un moteur, ça fait quoi au juste ? Commençons en douceur par l’explication de ce à quoi sert un moteur et son fonctionnement. Ce chapitre n’est pas un des plus simples car il va faire apparaître des notions de mécanique qui sont indispensables pour comprendre le mouvement. Prenons un moteur électrique des plus basiques qui soient : Transformation de l’énergie électrique en énergie mécanique Un moteur ça fait quoi ? .
What Can You Do With A Slide Rule? Peter Alfeld, --- Department of Mathematics, --- College of Science --- University of Utah There was a time when electronic calculators did not yet exist. This did not stop us from doing complicated things, like going to the moon, figuring out the double helix, or designing the Boeing 747. In those days, when we needed to compute things, we used slide rules which are marvelous and beautiful instruments! There are many pages about slide rules on the web, and you can still buy brand new slide rules (40 years old but never used, and still in their factory supplied box) in various places. The purpose of this particular and quite idiosyncratic slide rule page is to describe common scales used on slide rules, and the kind of mathematical expressions that could be evaluated with those scales. The two images on this page show the two sides of a particular slide rule in my collection. German made slide rules of that time (the late 1960s) usually come with an accessory plastic ruler. Why? . .
Microbial Slime Run your tongue over your teeth. If it's been a while since you last brushed, you may feel a filmy or fuzzy coating on your teeth. What's there is similar to the slimy coating you might feel if you stuck your finger down into a sink drain or that you might see coating the sides and bottom of a swimming pool that hasn't been kept clean. These are all examples of biofilms. Biofilms are communities of microbes. In this activity, you'll explore whether biofilms can form on all possible surfaces and which they grow best on. Print out these pages and follow the directions to do this activity at home. Note: This is a long-term activity that will stretch over a several days. You’ll Need: Note: Be careful handling sharp scissors. What To Do: 1. 2. The remaining part of the bottle looks like a cylinder. Flatten the piece and then cut into 5 equal strips. Punch a hole into each end of each strip. 3. 4. Continue to thread the strips onto the string, keeping them 3 cm apart. 5. 6. 7. Questions
Slowing 198.27.81.81&c=1&t=42173.03009375 This page details the use of Epson^ InkJet printers with pigment based inks to feed and directly print resist patterns to copper clad printed circuit board stock, ready for etching. Once you can feed the PCB through the printer for etch resist, you can then feed it back through the printer for solder mask (yes! Several people report that it works quite well!) and for a component "silk-screen". Toner transfer is probably easier to set up for and may be as fast, but direct ink is more precise, allows solder mask and component printing in the appropriate color, and most importantly, finer traces and spaces! The secret (discovered by Volkan) is that certain pigment based inks, such as MISPRO Inks^ (#MISPRO42-SET-MK) can be cured with heat to form a very strong resist. Barry Cooper^ reports^ that Epson ultra chrome k3 ink in his Epson R2400 printer also resists etchant if fully cured. Printer Modifications: "I am currently using 1/16" [PCB stock]. CD/DVD printing trays. Process PCB Preparation
Bacteria Can Make Zero-Viscosity Superfluids Bacteria can thin liquids to make them flow more easily. Astonishingly, they can do this to the point where the liquid they are swimming in becomes a superfluid, something with zero viscosity – a phenomenon previously only witnessed under extreme conditions, such as temperatures close to absolute zero. For the study, Dr. Harold Auradou of the University of Paris-Sud added E. coli to liquids in different concentrations. To make sure the bacteria focused on swimming, he put in enough nutrients to keep them alive, but not enough to tempt them to reproduce. Each solution was then spun in a rheometer to measure how the concentration of bacteria affected the ability of the liquid to flow. The effect was something like what physicists see as they test electrical resistance when cooling metals and certain ceramics. “If you use dead bacteria, nothing changes,” Auradou told Nature, which demonstrates the effect is a function of the swimming behavior, rather than the bacteria’s shape.
Electronics Tech Tips When working with SMT components, a solder-paste silk screen method plus a good baking in a special oven to make the paste flow works best. But for most of us working on small projects with a limited budget, angel hair solder and a fine tip iron that is ESD safely grounded is the way to go. Those new to SMD components may struggle with "tomb stoning," which happens when one end of the component is soldered and the other end pops up in the air. Here's an easy solution. You will need to use both hands (assuming they do not shake too much) one to hold the Iron and solder and the other to hold down the passive component with a small tool or tooth pick until the iron is removed and the solder has solidified. Bruce Weidner Columbus, Ohio Alternative PCB Etchant I thought I would share my experiences with creating quality circuit boards using household supplies as an etchant. I set out to create an etchant that, by my calculation, would be roughly 8 times cheaper than ferric chloride. Supplies:
Schematic Publisher Beta 1.0 RJWSoft Schematic Publisher is a complete schematic capture and publishing system. Schematic Publisher is perfect for students, hobbyists, and professionals. by Ray Wilson RJWSoft Schematic Publisher is a complete schematic capture and publishing system. Schematic Publisher is perfect for students, hobbyists, and professionals. Courtesy/Thanks to: Ray Wilson Description: By Ray Wilson: RJWSoft Schematic Publisher is a complete schematic capture and publishing system. What do I ask in return you say...? Easy to use functionality featuring: Schematic Capture, Edit & Print Schematic Publisher lets you create and edit schematic components and use them to create electronic schematic diagrams. Easily compose, edit and print schematic components, multi-page schematics, and panel diagrams. Zoom in for easy editing and component placement. Preview you schematics or lists prior to printing. Create, edit and save new schematic components in seconds for use in your diagrams. there is no limit to the type of components you can create from ICs to tubes. Wire List Generation Once your schematic is complete a wiring net list is just a mouse click away. Part List Generation
Front End Turns PC Sound Card into High-Speed Sampling Oscilloscope. Part 1 - End, Clock Generator By Doug Mercer, Analog Devices Various software packages enable the stereo sound card found in a personal computer (PC) to provide oscilloscope-like displays, but the low-sample-rate, high-resolution analog-to-digital converters (ADCs) and ac-coupled front end are optimized for 20 kHz or less of usable bandwidth. This limited bandwidth can be extended – for repetitive waveforms – by using a sampling front end ahead of the sound card inputs. Subsampling the input waveform with a high-speed sample-and-hold amplifier (SHA) – followed by a low-pass filter to reconstruct and smooth the waveform – effectively stretches the time axis, allowing the PC to be used as a high-speed sampling oscilloscope. Figure 1 shows a schematic for a plug-in attachment that can be used for sampling with typical PC sound cards. The AD783 SHA provides a usable large-signal bandwidth up to a few megahertz. Another screen shot was taken of a Gaussian sine pulse with a 1-MHz repetition rate (Figure 3). analog.com
Opamp Test and Design Board Opamp Design and Test BoardRod Elliott (ESP) Introduction Opamps are wonderful little building blocks, but quickly building a test circuit is a real pain. This project is basically what I use for a quick prototype, or for just mucking about with an idea. With four opamps to experiment with, even quite complex circuits can be made. Description For this project, two low-cost dual opamps are used. The layout of the top of the board is shown in Figure 1, and the opamp symbols are simply drawn on the top (non copper side) using a fine felt-tip pen. Figure 1 - The Board Top Layout Now that you have a board with a bunch of holes in it, you need to separate the various pads that are used for everything other than earth connections. Although it looks like there are way too many supply connections provided, you will probably kick yourself later if you leave them out. Figure 2 - The Hacksaw Blade Copper Cutter Figure 3 - Copper Cutting Plan Figure 4 - Mounting The Opamps Using The Test Board Main Index
Getting Started with FPGAs: The Development Environment and “Hello World” Getting started with FPGA development is much like getting started with any other piece of programmable silicon. First, pick the hardware to use. Next, set up the development environment. Finally, create your first “Hello World” application. In this article, I’ll take you through all three of those steps and, hopefully, get you past the most common MCU-to-FPGA gotchas. Supporting Information Previous Articles in This Series A Microcontroller Enthusiast’s First Look at Programmable Logic Choosing a Development Board While microcontroller development boards can be had for as little as a few dollars, I haven’t seen an FPGA board for less than around $50.00 US. My experience, thus far, has been limited to the Spartan and Zynq family FPGAs from Xilinx. My setup, as of this writing, costs $74.99 for the Papilio Pro FPGA board, and $7.99 for the Button/LED wing. The Papilio Pro with wings. The Spartan 6 chip used on this board has been around since 2009, so it isn’t the newest Xilinx chip.
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