[img]http://i.imgur.com/vUXOZQ7.png[/img]
[i]Cookies to Ddrl46 for the new banner.[/i]
Welcome to the thread dedicated to the wonderful world of electrical engineering.
Please read all of this post before you make a post, it contains a lot of useful information.
[img]http://i.imgur.com/3deLY.png[/img]
Electrical engineering is a rather broad term that can be applied to quite a number of subjects, but largely
electrical engineering or EE refers to circuit design, construction and when things go wrong (which they usually do), repair.
EE is by far one of the most accessible and arguably fun sciences to get in to, you don't need tons of cash to build
useful and interesting things plus it's generally quite a safe science as long as you take appropriate care around high
voltages.
[img]http://i.imgur.com/87QUH.png[/img]
Before you can start building stuff you need a few basic items that practically every single engineer relies heavily upon.
A digital and/or analog multimeter - For measuring voltage, current and resistance.
A breadboard - For rapidly building temporary circuits
Wire - To make connections on your breadboard, you can sometimes get breadboard jumper kits as well (23 [url=http://www.clag.org.uk/swg.html]SWG[/url] solid core recommended)
Basic tools - Screwdriver sets, pliers, wire stripper, tweezers, drill, etc
A soldering iron - If you intend to make a permanent circuit or want to remove components from broken equipment.
You'll also need some components to get started with, generally it's a good idea to make your first order fairly large and varied so you always
have some components to hand, there is nothing worse than running out or finding you don't have something, an example list follows:
[quote]
A pack of at least 500 carbon or metal film resistors of the E12 series.
A pack of electrolytic capacitors, 1uF to 1000uF of at least 25V.
A pack of ceramic capacitors, 10pF to 470nF (not critical but useful to have).
Selection of potentiometers
Selection of Light Emitting Diodes (LED), 3mm or 5mm size work well.
Rectifier diodes such as the 1N4007
Signal diodes such as the 1N4148
Some general purpose NPN and PNP bipolar junction transistors (2N3704, 2N4403, BC238, BC327)
Some general purpose N channel MOSFETs (2N7000)
Some general purpose N channel JFETs (2N5457)
A few power transistors (BD139, BD140, IRF540, FQP27P06)
General purpose operational amplifiers (LM324N, LM741)
General purpose comparators (LM339, LM311)
555 Timers (NE555)
Voltage regulator (LM317T, 7805)
Switches including the DIP variety which fit in breadboards
Electromechanical relay
[/quote]
This is just an example of some of the parts you might want, there is a vast number of components with some being
better suited to certain applications than others.
If you are unsure just ask, many of us will be happy to make you a shopping list for your specific budget.
[img]http://i.imgur.com/sNbTT.png[/img]
[url=https://docs.google.com/document/d/1u5UTcWSSzAKCu52mSKMIJsJKH4pbQS57VRre0cr0Jb0/edit?hl=en_GB&pli=1]Electronics Reference[/url]
List of various useful equations and other information.
[url]http://www.allaboutcircuits.com/[/url]
A very informative e-book that can be read online or downloaded, it explains things
very nicely and with plenty of pictures and diagrams so it is suitable for beginners.
I highly recommend although the book is not complete.
[url]http://www.eevblog.com/[/url]
Excellent video blog all about electronics, definitely worth watching.
Also has an excellent forum suitable both for beginners and professionals.
[url]http://www.williamson-labs.com/[/url]
Some useful images but the site design will make your eyes bleed.
[url]http://www.repairfaq.org/[/url]
Interesting information related to electronics repair.
[b]Tutorials[/b]
[url=https://dl.dropbox.com/u/59112523/how2ardweeno.png]Chipset's guide to interfacing microcontrollers with high power devices[/url]
[url=http://i.imgur.com/JMGJr.png]Chryseus' guide to transistor amplifier design[/url]
[img]http://i.imgur.com/0r4KT.png[/img]
[img]http://upload.wikimedia.org/wikipedia/en/9/93/The_Art_of_Electronics.jpg[/img]
[b]Art of Electronics by Paul Horowitz and Winfield Hill[/b]
Without a doubt the most complete and informative book on electronics, although the
current 2nd edition is rather old (1989) it is still extremely relevant to modern electronics.
If you're going to buy any book this should be the one, although it is not designed for beginners.
[img]http://i.imgur.com/lJsRW.png[/img]
[b]Complete Digital Design by Mark Balch[/b]
An excellent book that covers all the basics such as boolean logic,
karnaugh maps, binary arithmetic and more advanced topics such as serial
communication, microprocessors and the practical design of digital circuits.
[img]http://i.imgur.com/LLUjU.png[/img]
[b]Principles of Electric Circuits by Thomas L. Floyd (9th ed)[/b]
A very good book for beginners that unlike most comes in an electron flow
version as well, if you prefer that. The book is full of well drawn diagrams and
helpful pictures which makes reading easy and fun, in addition at the end of each
chapter there is a quiz to make sure you fully understand what you have read.
[img]http://i.imgur.com/EJF7C.png[/img]
[b]Troubleshooting Analog Circuits by Robert A. Pease (Bob Pease)[/b]
An excellent book by an excellent author, this book contains a lot of useful
information that is invaluable if you are interested in getting into electronic
repair.
[img]http://i.imgur.com/iuSjW.png[/img]
[b]Power Electronics Handbook by Muhammad H. Rashid et al[/b]
A huge amount of information on power circuits and components
a must have if you're interested in power electronics.
[img]http://i.imgur.com/EL9kLjg.png[/img]
[b]Getting Started in Electronics (Forrest Mims)[/b]
Excellent book for beginners with plenty of well drawn illustrations and
straightforward explanations, highly recommended.
[img]http://i.imgur.com/drJqn1p.png[/img]
[b]Semiconductor Physics and Devices 3rd ed (Donald Neamen)[/b]
An advanced yet very informative book on semiconductor physics and device
operation, if you want a better understanding of semiconductors this is definitely
worth a read.
[img]http://i.imgur.com/kudaa.png[/img]
[url=http://nptel.iitm.ac.in/video.php?subjectId=122106025]Basic Electronics, Prof T.S.Natarajan - NPTEL[/url][img]http://www.facepunch.com/fp/ratings/winner.png[/img]
[url=http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-002-circuits-and-electronics-spring-2007/]MIT 6.002 complete lecture - Circuits and Electronics[/url]
[img]http://i.imgur.com/SarKH.png[/img]
Bitsbox - Small selection of components but very cheap shipping, £1.50 UK, £2.75 Europe, £4.00 anywhere else.
RS - A well known supplier with large selection, shipping is fairly cheap but no Paypal.
Farnell - Another excellent supplier with a very large selection, minimum order applies and no Paypal.
DealExtreme - Sells a lot of made in china stuff but you can get some really good deals such as the Rigol DS1052E.
Rapid - Decent selection but not the cheapest, shipping outside the UK is also fairly expensive.
Maplin Electronics - Similar to rapid but even more expensive, not available outside the UK as far as I'm aware, avoid.
Digikey - Excellent selection of components but fairly expensive shipping.
Sure Electronics - Small selection but some good value for money component kits.
Sparkfun Electronics - Nice selection with some good deals, still quite expensive.
RSH Electronics - Small selection with some great bargain packs, cheap delivery £4.00 international
Tayda Electronics - Decent selection of cheap parts, direct from Thailand so expect some delay in delivery.
[b]Ebay Sellers[/b]
[url]http://stores.ebay.com/Thai-Shop-Etc[/url] - Cheap components
[url]http://stores.ebay.co.uk/Tayda2009[/url] - More cheap components
[img]http://i.imgur.com/vUYZE.png[/img]
Working with electricity is generally quite safe, however here are a some useful tips that will help you avoid severe injury or in the worst case death.
[b]
Avoid working with mains electricity unless you are confident with what you're doing
Probe live circuits with your right hand and keep your left hand in your pocket
Keep your hands clean and dry
Do not wear any metal objects even around low voltage
Never go near high energy (3 phase) systems with a non-industry grade multimeter
Use a properly fused multimeter to avoid risk of explosion
Ensure high voltage capacitors are discharged before touching a circuit
Never make changes to household wiring unless you REALLY know what you're doing
NEVER EVER play around with microwave ovens they're lethal
Always check the mains cord on unknown equipment for damage[/b]
[img]http://i.imgur.com/KSl0E.png[/img]
Keep your breadboard clean and perform regular checks for high resistance or open circuits.
Know how to use your multimeter properly and safely.
Get a good quality soldering station and use leaded solder.
Make sure your iron has temperature control.
Flux is very useful particularly when soldering older oxidized stuff.
Never rely on circuit simulations or assume they're correct.
Get an oscilloscope as soon as possible, they're extremely useful.
Don't buy toy oscilloscopes like the DSO Nano or USB scopes.
Always draw out your schematic before building to help avoid accidents.
Keep your work area clean and well lit. (if possible)
Always experiment it helps greatly in learning, do not rely on a textbook alone.
Design your circuits using common sense and some basic math, a full analysis is rarely needed.
Breadboards are not suitable for high frequencies or high current. (> 1A)
Be very aware of possible ground loops, particularly if using an oscilloscope.
Keep your soldering iron tip clean, never dip it in flux or any other liquid and avoid applying pressure to it.
Use small soldering iron tips, preferably chisel type.
A soldering gun should never be used on circuit boards.
Never use solder meant for plumbing, 60/40 and 63/37 electronics solder with a flux core is standard.
Learn how to read the information given in datasheets and apply it to your circuit.
If you have anything to add post or PM me.
[quote]
[b]Previous Threads[/b]
[url]http://www.facepunch.com/threads/880...ed-Programming[/url] V1 - By Ddrl46
[url]http://www.facepunch.com/threads/1092907[/url] V2 - By Chryseus
[url]http://www.facepunch.com/showthread.php?t=1160372[/url] V3 - By Chryseus
[url]http://facepunch.com/showthread.php?t=1207850[/url] (V1 of Electrical Engineering) - By Chryseus
[/quote]
[img]http://i.imgur.com/zUyXXho.jpg[/img]
My tooling block arrived
[HR][/HR]Fasdafasdafdsa
[QUOTE=Van-man;39733995]So instead of reinventing the wheel when it comes to protecting li-ion battery packs (with cells hooked up in parallel), I decided to modify existing & cheap hardware meant for doing so to my needs.
[IMG]http://puu.sh/29dW1[/IMG]
Shitty photo, but you get the idea[/QUOTE]
And the reason for hooking cells in parallel, is that it makes it MUCH easier to design a charger and I can use cheap off-the-shelf protective circuits.
I don't plan on using them in applications where short bursts of shitload of current is needed, but rather long lasting low-power applications.
[QUOTE=DrLuckyLuke;39734228][img]http://i.imgur.com/zUyXXho.jpg[/img]
My tooling block arrived[/QUOTE]
Are there any other uses for it apart from aligning stencils?
[QUOTE=alexaz;39736784]Are there any other uses for it apart from aligning stencils?[/QUOTE]
Paperweight.
[QUOTE=alexaz;39736784]Are there any other uses for it apart from aligning stencils?[/QUOTE]
It's a really boring dot-to-dot puzzle
[editline]27th February 2013[/editline]
Do AVRs need the extra cap across AVCC if you're not using the ADCs?
[QUOTE=alexaz;39736784]Are there any other uses for it apart from aligning stencils?[/QUOTE]
Nope
[QUOTE=Van-man;39735529][HR][/HR]Fasdafasdafdsa
And the reason for hooking cells in parallel, is that it makes it MUCH easier to design a charger and I can use cheap off-the-shelf protective circuits.
I don't plan on using them in applications where short bursts of shitload of current is needed, but rather long lasting low-power applications.[/QUOTE]
Cool mod, but it's generally bad practice to use the green/yellow wire for anything other than actual (mains) ground.
I have this 12volt 7Ah Lead Acid battery that I am using to power a car amplifier in a bag, currently I am taking the battery out everytime and charging it with a big slow charger that I have in my shed. What I want to do is put a smaller charger in, now I found this on DX :
[url]http://dx.com/p/emergency-12v-lead-acid-battery-charger-100-240v-55157[/url]
Which seems small enough to fit inside my bag without taking too much space but then I also found this :
[url]http://dx.com/p/rechargeable-9000mah-li-ion-emergency-power-battery-for-camcorder-walkie-talkie-camera-more-73774[/url]
A smaller battery with more ah and a charger.
Any thoughts ?
[QUOTE=quincy18;39748219]I have this 12volt 7Ah Lead Acid battery that I am using to power a car amplifier in a bag, currently I am taking the battery out everytime and charging it with a big slow charger that I have in my shed. What I want to do is put a smaller charger in, now I found this on DX :
[url]http://dx.com/p/emergency-12v-lead-acid-battery-charger-100-240v-55157[/url]
Which seems small enough to fit inside my bag without taking too much space but then I also found this :
[url]http://dx.com/p/rechargeable-9000mah-li-ion-emergency-power-battery-for-camcorder-walkie-talkie-camera-more-73774[/url]
A smaller battery with more ah and a charger.
Any thoughts ?[/QUOTE]
Give it a shot, the lithium battery might not be able to cope with the discharge though, if that car amplifier draws a lot of current. It's easy though, if the battery gets hot, don't use it.
[QUOTE=chipset;39748924]Give it a shot, the lithium battery might not be able to cope with the discharge though, if that car amplifier draws a lot of current. It's easy though, if the battery gets hot, don't use it.[/QUOTE]
Hmm, sounds a bit risky. The car amplifier is a small 200 watt one though and its throttled down to about half.
[QUOTE=quincy18;39750189]Hmm, sounds a bit risky. The car amplifier is a small 200 watt one though and its throttled down to about half.[/QUOTE]
Someone in the comments wrote that he had problems drawing 3 amps from it, so it's probably a no-go. Look at hobbyking, they have a huge selection of fair priced lipo's. And several where you can draw 100's of amps.
[QUOTE=BuG;39752065]Look at hobbyking, they have a huge selection of fair priced lipo's. And several where you can draw 100's of amps.[/QUOTE]
Those batteries don't have many recharge cycles though.
He's be better off with a bigger pack of ordinary lithium cells, and a buck/boost/buck-boost converter with a set cut-off voltage to protect the pack.
[QUOTE=Van-man;39753745]Those batteries don't have many recharge cycles though.
He's be better off with a bigger pack of ordinary lithium cells, and a buck/boost/buck-boost converter with a set cut-off voltage to protect the pack.[/QUOTE]
Sounds pretty good, problem is my knowledge of electronics is limited to my arduino and some basic electronics skills. Can anyone help me design this with parts from bitsbox and dealsextreme ?
I would not trust DX at all for batteries, they practically always have a far lower capacity than expected, your not going to be able to get a decent lithium battery for anything less than £100, something like
[url]http://www.deben.com/lithium-polymer-battery-packs/12v-10ah-lithium-polymer-battery-pack.html[/url] will do the job but the price makes it rather impractical for your use.
You really can't beat lead-acid when it comes to low cost and high capacity.
You can fast charge lead-acid without too much issue, although it will of course reduce the life and may effect total capacity, the usual method for a fast charge is to charge
with a constant current of 1C (or slightly more) for about half an hour, this will bring the charge to around 50%, followed by a longer
constant voltage charge for about 5 hours which will bring it to around 90%.
Thanks for al the info, I will stick with my lead acid battery then for $ issues. Instead of buying a adapter / charger to charge it I would like to try and build a charger myself (withing a reasonable amount of money) as a fun side project. Any tips / suggestions ?
[QUOTE=Van-man;39753745]Those batteries don't have many recharge cycles though.[/QUOTE]
That's interesting, something you have a source on? Or just your experience?
Because I was going to use one of them, far far below it's rated maximum discharge rate, I thought that'd prolong the life. Also use their charger and balancer of course.
[QUOTE=BuG;39762337]That's interesting, something you have a source on? Or just your experience?
Because I was going to use one of them, far far below it's rated maximum discharge rate, I thought that'd prolong the life. Also use their charger and balancer of course.[/QUOTE]
That's what they're designed for.
R/C Li-ion batteries can deliver extremely high amperage bursts, at the expense of lifetime.
Basically lifetime has literally been sacrificed to gain the ability to deliver a shitload of current quickly, compared to the cells total capacity.
Flashlight forums usually have a thread or two on that.
[img]http://puu.sh/2anHZ[/img]
Switch S1 & S2, S3 & S4 should be DPDT.
Transistor should be rated for maximum charge current +20% and be a darlington pair.
Don't forget to use a good filter cap, 2200uF @ 25V should do the job.
Just finished designing and coding my first real hardware project for the new company I'm working for, a controller circuit with a LCD display and stepper motors; this will go into a lab system and control a microscope.
The rest of the project is temperature and UV light control (used for sterilisation) then video transmission from the microscope, I'll code it in C++ with QT and gstreamer.
Just waiting on the rest of the parts to start assembling the prototype, I'll post pictures if they allow it.
With the ongoing project of my solar charger, I decided to put a couple cheap RadioShack solar panels(Model #277-046) to the MPPT test and drafted this spreadsheet of their Fill Factor, MPPT, etc.
[URL]https://docs.google.com/file/d/0B54oyVnVRa5xcm1EY3ZsWUMtUms/edit?usp=sharing[/URL]
Needless to say, they're utter shite (With fill factors on average of 0.18). Their advertised power output was 0.5W (Isc=84mA, Voc=6V), however the average MPPT was around 78mW. I do believe these panels are poly crystalline silicon.
I'm gonna scope out some proper mono-crystalline cells, recommendations appreciated.
Grabbed my arduino and two speakers and started messing with them today. I know that I was going to test something, but then I started to mess around more and more, and now I've forgotten completely what I wanted to test out... Anyways, I'm thinking about making an amplifier, after I fried my last one... (it was old and probably had a bunch of dust) I've missed having a use for my speakers and my sub...
I'll need an AUX input, two/three RCA inputs (not sure yet), and of course a selector for all three/four inputs. I think I've already got a transformer and connectors for the speakers, which I think I'll manage to salvage from the old amp. (the Sony amp I used has it's own connections on the back, and I have cables to match it)
[img]https://www.indybay.org/uploads/2013/02/08/800_picture_35.jpg[/img]
[url=https://www.indybay.org/newsitems/2013/02/08/18731689.php]Drone Spotted Over West Oakland[/url]
Hypothetical: how could you disable/destroy/render ineffective one of these bad boys? Could you broadcast random noise over a range of radio frequencies until you hit the right one and disrupt it? Are they even controlled via radio? How much do we even know about them?
[QUOTE=Nigey Nige;39775145][img]https://www.indybay.org/uploads/2013/02/08/800_picture_35.jpg[/img]
[url=https://www.indybay.org/newsitems/2013/02/08/18731689.php]Drone Spotted Over West Oakland[/url]
Hypothetical: how could you disable/destroy/render ineffective one of these bad boys? Could you broadcast random noise over a range of radio frequencies until you hit the right one and disrupt it? Are they even controlled via radio? How much do we even know about them?[/QUOTE]
Jam the GPS frequencies, that'll render it useless.
[QUOTE=Nigey Nige;39775145]
Hypothetical: how could you disable/destroy/render ineffective one of these bad boys? Could you broadcast random noise over a range of radio frequencies until you hit the right one and disrupt it? Are they even controlled via radio? How much do we even know about them?[/QUOTE]
Broadcasting random noise over a range is considered jamming and could land you in alot of trouble with the FCC.
It is possible (If you know the right frequency) to jam it with noise yes, depending upon how its controlled (FSK, PWM, other transmission protocols), thats just the science of it.
However I suggest you don't seek help to jam these things and instead just take it up with authorities, don't bring these kind of issues here.
[QUOTE=LoneWolf_Recon;39775203]Broadcasting random noise over a range is considered jamming and could land you in alot of trouble with the FCC.
It is possible (If you know the right frequency) to jam it with noise yes, depending upon how its controlled (FSK, PWM, other transmission protocols), thats just the science of it.
However I suggest you don't seek help to jam these things and instead just take it up with authorities, don't bring these kind of issues here.[/QUOTE]
No, I mean it's actually a hypothetical. I don't live in the US, just interested.
[QUOTE=Nigey Nige;39775255]No, I mean it's actually a hypothetical. I don't live in the US, just interested.[/QUOTE]
In the spirit of EE I'd recommend a coilgun
[QUOTE=Van-man;39775281]In the spirit of EE I'd recommend a coilgun[/QUOTE]
*Liquid Nitrogen cooled Superconducting Coil Gun powered by 0.00000005 ohm ESR 2500F Super Caps :v:
...With a laser sight
[QUOTE=LoneWolf_Recon;39775388]*Liquid Nitrogen cooled Superconducting Coil Gun powered by 0.00000005 ohm ESR 2500F Super Caps :v:
...With a laser sight[/QUOTE]
Save the superconductors for a railgun! With coil what you want is a well timed multi-stage assembly.
Not that I'd know anything about it, honest...
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