tag:blogger.com,1999:blog-5051684.post2307216833384245665..comments2019-02-27T09:07:50.595-08:00Comments on Xenomachina: Voodoo ElectronicsLaurencehttp://www.blogger.com/profile/12946206226063265718noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-5051684.post-71351204230518400512010-07-18T21:55:43.156-07:002010-07-18T21:55:43.156-07:00Great tutorial.
Thank You,
GuruSantiago
Want to l...Great tutorial.<br />Thank You,<br />GuruSantiago<br /><br />Want to learn more about electronics?<br /><br />The GuruSantiago can help. Checkout his videos here:<br /><br />http://www.youtube.com/user/ElectronicsIsFun<br />And follow him on twitter @ElectronicsFunGuruSantiagohttps://www.blogger.com/profile/12057066770652239430noreply@blogger.comtag:blogger.com,1999:blog-5051684.post-81926122550475720442008-07-08T00:27:00.000-07:002008-07-08T00:27:00.000-07:00Well,it looks like the other posters have answered...Well,it looks like the other posters have answered your questions.<BR/><BR/>The funny thing is I thought I had invented the term "Voodoo Electronics",so I thought I would Google to see if there were any references==oops! pages & pages!.<BR/><BR/>My definition is a bit different to yours,in that I apply it to things like people thinking a High current low voltage supply is more dangerous than a high voltage low current supply.<BR/>Ohms Law is a new & startling concept to them!<BR/><BR/>Another case is where a production run was held up for days because there were no 1.1KOhm resistors available for a particular RC network.<BR/>There were hundreds of 1.0kOhm & 1.2kOhm resistors available.<BR/>The C part of the circuit was a 47uf electrolytic +- 20% tolerance hor worse!<BR/><BR/>this decision was made by a so-called "technical Specialist"!<BR/><BR/>VK6ZGOAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5051684.post-68974127099851449092008-06-29T22:50:00.000-07:002008-06-29T22:50:00.000-07:00Anytime.The question about Excessive Current is ac...Anytime.<BR/>The question about Excessive Current is actually a really important one - it's hard to figure out how to power a LED properly if you're relying on your everywhere-cited ohm's law.<BR/><BR/>Instead of having a resistance like most components, LED's have a "voltage drop", and basically no resistance.<BR/><BR/>So to figure out how large of a current-limiting resistor to attach to a LED, you basically need to know how much current the LED runs at, how much voltage your source is, and what the forward voltage drop of the LED is.<BR/><BR/>If you're running lets say .. 5V, and your LED has a forward drop of 0.7v and requires 20ma of power (pretty typical for a small red led).. the math goes like this.<BR/><BR/>5v-0.7v == 4.3 volts. So if you've got 4.3 volts left, and you want to use your resistor to limit it to 20ma, now here is where your ohm's law comes in: 4.3 / 0.020 == 215. So a 215 ohm resistor (220 is fine, obviously).<BR/><BR/>Now lets say you want to run two LED's in a row (series). 5V - 0.7 - 0.7 == 3.6V. 3.6 / 0.02 == 180 ohm's will limit it to 20ma (powering both).<BR/><BR/>If you'd like to run your LED's in parallel, you can simply add their current usage together (so 2 of those would be 20ma, but a total of 0.7V drop). It's best to avoid running lots of LED's in parallel, though, since it tends to distribute more current to the worst performing one (leading to more likely failure).<BR/><BR/>And on that note, I need to lay off the caffeine and blog commenting ^_~Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5051684.post-9600344181337007572008-06-29T20:23:00.000-07:002008-06-29T20:23:00.000-07:00Thanks, "anonymous". That's a very clear explanat...Thanks, "anonymous". That's a very clear explanation.Laurencehttps://www.blogger.com/profile/12946206226063265718noreply@blogger.comtag:blogger.com,1999:blog-5051684.post-47704975563715662292008-06-29T20:06:00.000-07:002008-06-29T20:06:00.000-07:00Hey,When a motor or solenoid turns off, it generat...Hey,<BR/>When a motor or solenoid turns off, it generates a *large*, reverse polarity voltage spike. This is due to the coil trying to resist the change in magnetic field (by compensating with voltage). The total power of the spike is small (since the current is low), but the voltage is very dangerous for digital electroinics - if you don't protect yourself, you'll notice simple logic IC's going wonky after the nearby solenoid goes off a couple hundred times.<BR/><BR/>The zener diode basically "breaks down" when there's more than a couple volts of current BACKWARDS over the motor - at which point it just shorts them out.<BR/><BR/>In fact, a zener isn't reallly required - a regular diode usually seems to work well.<BR/><BR/>--Junior in Computer Engineering at UIUC / kid who likes to build things.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5051684.post-81629748356920377962007-06-18T08:18:00.000-07:002007-06-18T08:18:00.000-07:00Thanks for interesting blog!Thanks for interesting blog!Rob Halfordhttp://www.gradingrocket.comnoreply@blogger.comtag:blogger.com,1999:blog-5051684.post-49459229087433650692007-06-05T10:40:00.000-07:002007-06-05T10:40:00.000-07:00Let me start with the observation mobile phone is ...Let me start with the observation <BR/>mobile phone is notorious for introductiopn of noise in all kinds of electronic gears.<BR/><BR/><B> [noise] </B> and <B>[error]</B> - are these two inherently different? Ontollogically probably not that much but we will nevertheless try to find distinct definitions for these two.<BR/><BR/><B> [noise] </B> comes from an external (whereby external is a question of perspective) source beyond your control and defined through the point in time and the intenisty it occurs. But as far as you know noise is a random phenomenion - easy to explain, can be filtered out efficiently, but next to impossible to sensibly predict. <BR/><B>[error]</B> is a much more accesile term and generally can be viewed as digression from a Standard and we strive to predict errors, or better .You can't eliminate erors them but you can design with them in mind.<BR/><BR/>In short, somewhat simplicistic - nature does a great job as noise provider, you try to get on par with it, producing quality errors - this is clearly the job, where one or more of us humans can excel.!<BR/><BR/>Going forward, we conclude that we wanna try to filter out noise and deal with errors as efficient as possible. <BR/><BR/>As it turns out we can use our two prevalent tools, we have as technicians - namely math and the human brain (the latter one best be your own - rented ones have shortcomings regarding configuration options and you never know3n what they have been up to in the past. <BR/><BR/>The approach 'filter noise' 'deal with error' works remarkably well for those proficient with both.<BR/><BR/>With filters,the most efficient ones (i.e linear filters in continous time aka Kalman filters) are not easily accessible to the general public as they are based on stochastic differential equations, simply meeaning, you deal with analysis and probability theory (stochastics) simulataenously. Fabolous pastime on rainy Sundays, IF AND ONLY IF you like it. <BR/><BR/>You don't really need to be able to do the math, somebody else most likley already has. <BR/><BR/>As for errors, error prediction and calculation of the development of these aberrations are mandatory at least in Europe in case you strive for an engineering degree. The whole stuff, though of major significance is mathematicxcally rather dull and based on statistics and a touch stochastics. <BR/><BR/>How to find out where to add tolerances based on likely occurences of errors or what to watch out for in terms of filters? Mostly experience plus some common sense. The easiest approach though is to leave that stuff out of your device completely and strart using it right away. Whenever it stops working under certain circumstances, u have most likely hit an error condition. Whenever the use of the device gets really unpleasant you might think of some filtering. And think again about unpleasant, should the governmment pay youn a zillionj to create a new highly efficient electronic torture device.<BR/><BR/>A last word of caution: Funny as much does sound, don't fool yourself. If you intend to build an electronics device for resale, dealing with epsilon (the tiny error) will be one of the challenges in order to get all the needed compliance seals. <BR/><BR/>Was a fairly long comment - should you have read 100%, understood at least 50% and still not be mind numbed by excessive boredom, you might es well consider pursuing a techie degree - preferably at a university of your choice.<BR/><BR/>hth, geraldsardonic.smilehttp://dev-0.blogspot.com/noreply@blogger.comtag:blogger.com,1999:blog-5051684.post-356432718420172652007-06-05T10:11:00.000-07:002007-06-05T10:11:00.000-07:00Get yourself a copy of "Horowitz and Hill". It's t...Get yourself a copy of "Horowitz and Hill". It's the bible.Markhttps://www.blogger.com/profile/16112093984435209050noreply@blogger.com