Electronics, Lighting, & Gadgets - Pragmatic electronic information?
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02-07-08, 02:13 PM
I love to read and tinker, and I would like guidance about a good book or web site that presents fundamental topics for designing and building simple circuits.
I mean REAL simple circuits like the ones discussed in the thread about powering USB devices with a dynamo.
It would cover types of components (diodes, resistors, capacitors) and even specific types... I know when I went to an electronic parts site to consider building a USB charger for my dynamo, the array of types of diodes just confused me. Or was it one of the other components?
It would also cover things like rectification, ohm's law, parallel and series circuits, and anything else needed to understand the easy stuff like the thread referenced above, or other tinkerer's circuits.
I don't want to be an electronics engineer, but I would like to be able to talk with one about easy stuff. :)
I like exercising my mind, and doing things on my own, so you would really be helping me out.
I suggest you visit your local library and pick up a few beginner's books.
02-07-08, 07:03 PM
I have been meaning to go get a library card (I just moved).
Anyone have specific recommendations?
02-07-08, 07:25 PM
I have Understanding Electronics by G. Randy Sloane and R. H. Warring. I have read it twice and referred to it even more often. It does have a couple of small errors in it that made my head hurt until I realized they were errors. I think it does a good job of what you want. It also has some small projects with each chapter.
A couple of years ago I bought a circuit simulation program on close-out at Radio Shack. It allows you to set up circuits like you mentioned, but on a computer. If you have something wrong, a component "overheats" and "blows" without needing to buy a replacement and solder it into place. When the virtual circuit works as it should, buy components and build the real thing. Read about it at: http://www.globalspecialties.com/protolab4.html.
02-07-08, 08:01 PM
Stolen shamelessly from another forum...
Falstad Circuit Simulator (http://www.falstad.com/circuit/) - It's written in terrible, icky Java, but it's an awesome program. Newbies absolutely MUST go here. Build simple-ish circuits and see what they can do. It's not as powerful as commercial simulators or really all that accurate, but it's quick and damn fun to play with.
Dutchforce Electronics Forum (http://www.dutchforce.com/~eforum/index.php) - The best electronics forum on the internet I've found. Lots of discussion on projects from the simple to the complex. The community really knows their stuff too!
Lessons in Electric Circuits (http://www.ibiblio.org/obp/electricCircuits/) - Free online textbook on the matter. Excellent resource for people just starting out. Explanations are not super-dry and he gives understandable examples. Some things he's not so good at explaining though, and I'll try to fill in those gaps. Oh yeah, and the book isn't complete either.
Analog Dialogue (http://www.analog.com/library/analogDialogue/) - Articles from Analog Devices on slightly more advanced topics. Lots of articles on uses for Analog's parts, and some great information.
Introduction to DC Circuits (http://www.play-hookey.com/dc_theory/index.html) - Simple introduction to DC circuits. Pretty quick and dirty explanations.
For practical experience get some circuit kits for an electronics shop, they're cheap, have everything you need to build. Large variety of projects, Im sure there's something of interest for most people in them.
Here is how you power USB devices with a bicycle dynamo.
The 4 diodes are standard Schottky Barrier Rectifier types carrying a parts designation of 1N5818. Google 1N5818 and you will find page after page of information. The reason for using Schottky diodes is due to the lower voltage drop across the junction making them a little more efficient than standard reciter doides. These 4 diodes form what is called a bridge rectifier used to convert AC to DC. Here is a photo of these diodes soldered to a terminal board mounted to the front reflector and front rack bracket.
The 4 Ni-MH batteries regulate voltage and current and provide filtered and safe power for the USB connector and any devices plugged into it. The batteries start to impose a high impedance load on the dynamo as voltage approaches 1.25. Four series connected 1.2 volt Ni-MH batteries will limit voltage to 5.2 volts which is within the limits set for USB devices. It's also perfect when recharging them. The batteries also use excess current produced by the dynamo as recharging current. In essence they provide a place for excess current to go sort of like water filling a lake behind a dam. These batteries also provide power when the dynamo is not. Your USB powered devices will continue to operate and recharge while your stopped or climbing that steep hill. The LED lights are setup with the resistors shown so they draw 380mA of current from the batteries when all USB devices are unplugged from the USB connector and S1 is closed for riding after dark or in a tunnel. The reason 380mA was chosen was due to the fact that 120mA is the suggested slow recharge current for Ni-MH batteries. This allows your lights to continue to burn even while stopped in traffic or climbing steep hills and are slowly recharged when your moving again. The 470mF capacitor across the 1-watt LED is not required when the batteries are in the circuit but is included in the event the batteries are lost or damaged. That capacitor becomes a filter providing the headlight LED with smooth DC current eliminating slow speed flickering and damage if it were not there. It's location is in the headlight across the LED terminals. A dynamo without a load can produce very high voltages and that capacitor can easily store it for a long time without a load. If there is an intermittent or poor connection between the capacitor and LED causing the capacitor to store and then discharge high voltage across the LED consequently burning it out.
Here is a free online course in Basic electricity and electronics.
I attended this school in 1980 in San Diego right after Boot camp. It starts assuming you know nothing and at the end you can pretty much work on anything!
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