EE Advice: Jump-Start Your Engineering Education with Peavey

[Peavey]

Hello all, I'm Peavey. (Excuse me if this is not the place to be introducing myself, but I'm going to be talking more about electronic engineering rather than introductions.) So. I am going into college next fall semester, and majoring in electronic engineering. I am not very knowledgeable on the subject, as I am really almost limited to knowing how to wield a soldering tool and a few others. Anyways, to the point: I am trying to teach myself to get ahead in the game a bit than my future classmates. I've been learning such things as basic Ohm's law and very, very basic calculus formulas. I was wondering if anyone would know how I could get farther in the game and get a jump-start on learning how to experiment with engineering. I am not taking any classes at the moment that has anything to do with engineering of any sort. I am almost certain that people who are going to be in my classes next semester will be ahead of the game.

What I have been wanting to do is a simple idea (that will hopefully get me started on advancing in EE), but as I've seen so far, is somewhat-complex to put into reality. I want to make a switch that turns on an LED light through the power-source of a battery.

Thank you for your time. Again I am sorry if this thread is in the wrong area, as I am new to the forum.

- Peavey

 

[MATLABdude]

Welcome to PhysicsForums, and electronics in general!

I'd recommend a breadboard, some hook-up wire, and a microcontroller (for instance, an ATMEL ATtiny or a PIC 18F). Plus an assortment of resistors and a couple of LEDs, diodes, capacitors, the sort of stuff you find in a grab bag at your local electronics hobby shop, assuming that you still have one that isn't Radio Shack. HINT: make friends with the tech at your schools, they are invaluable and will have much more hands on and practical experience than anybody else)

If you search the forums for microcontroller recommendations, you'll find threads where the topic has been explored. Most of the time, the recommendation is for an Arduino or some such, which has a much easier learning curve and programming (NOTE: you'll need a programmer if you get the raw PIC / ATMEL chips). For power supplies, find an old wall wart (AC adapter) that puts out 5 or 12V or some such.

The microcontroller has revolutionized electronics--you can now use a tiny 8-pin micro to perform tasks that would have previously required a breadboard full of components and analog stuff.

You'll find a thread that's stickied above which has recommendations for tools and equipment that you might wish to have in your toolbox. Since you're probably not made of money, don't go blowing a wad on all this stuff (or lots and lots of components) right away! Lastly, I'd recommend a good toolbox, and some compartmentalized storage containers (don't spend a lot of money here)--they'll keep your stuff organized and reduce the amount of clutter that seems to invariably build up around hobbyists.

Good luck!

 

[Peavey]

Thanks. I am getting a breadboard in the next few weeks or so. Is there something wrong with RadioShack? It's really about the only place I know that has the proper electronics and equipment in my area.

I was looking through some of the tool threads before and after I posted this thread, and definitely found it to be useful. I'm going to be doing a bit more searching after this, but would you or anyone else happen to know where I could start as tutorial-wise for an absolute beginner? I know very little, but I'm afraid some of it may be wrong, as I taught most of it myself just based off of the internet. For instance, I've heard of most of the terminology you talked about, such as microcontrollers and diodes. I know capacitors, LED's, and resistors of course, but I am not to familiar with the actual definitions of microcontrollers and the others.

I have quite a few friends in the tech department at my school, but mostly towards the computer-side rather than engineering. I'm better at computers than any of this, at least, as of yet. This is a career I am willing to pursue, or if it doesn't work out as a profession, then maybe just a great hobby.


Thanks.

Peavey

 

[mdjensen22]

You can order parts and whatnot from the below, but they also have some pretty good reference links and 'hints and tips' for you to build from (check the tabs at the top of the page)
http://www.elexp.com/index.htm[/URL]

I'm not sure if that's what you're looking for, but it's a good place to start where it's all in one location.

 

[Peavey]

Those references and tips will definitely help, thanks. Is it a bad idea for me to jump right into trying to complete the LED circuit (that I mentioned in the first post) without having that much prior knowledge? I thought so myself, but I had tried just replacing an LED that went out on my iPod speakers, but I'm pretty sure I bought the wrong one in terms of voltage. It uses 4 AA batteries (Which I'm assuming is 6V?) with one resistor, but I bought a 2V LED. Now I actually look at the package. It was a stupid mistake, I know, but at least now I know what to look for in terms of voltage. I wanted to do it to see if it was simple enough by just desoldering the old LED and putting in a new one. It wasn't. I'm probably not going to attempt it until I start learning more about, well, everything. Haha.

 

[b.shahvir]

Slow n steady wins the race. Pls. follow electrical safety and do not rush thru ckt. making in excitement. Understand the do's & don'ts on electrical safety and general principles of EE... Enjoy. All the best!

Regards,
Shahvir

 

[Fish4Fun]

Peavey,

As far as the LED goes, there are two parameters that are important Vf, If. Vf = Forward Voltage, If = Forward Current. For an LED with Vf = 2V and If = 15mA, and a power supply of 6V you would use Ohm's law:

6V - 2V = .015A * R ==> 4V/.015A = R ==> 266 Ohms

The closest "standard" 5% or 10% value resistor would be 270 Ohms. So you would place a 270 Ohm resistor in series with your LED to make it "light".

I would suggest you start with just the LED and the resistor. You might then replace the resistor with a 500 Ohm potentiometer. With the potentiometer you can vary the brightness of the LED, but be careful, if you set the resistance too low, you will burn out the LED. Next I would suggest you play with a 555 timer. There are numerous circuits on the net that involve a 555 and an LED. With the 555 circuit you will begin to get a "feel" for how capacitors and resistors work in a dynamic circuit.

The importance of Ohm's law cannot be over-stated. If you "play" with electronics you will use it constantly.

Along with your breadboard and jumper wires, I would strongly urge you to purchase an assortment of resistors and capacitors, some 7805 voltage regulators, a couple 555 timers and some potentiometers (100, 500, 1k, 5k, 10k, 20k would be a good start).

uControllers really are fabulous devices, but I think you should focus on simple circuits first. Adding an assortment of logic gates will give you lots more to play with.

Fish

 

[Peavey]

Concerning breadboards, would it be easier to learn on a solderless breadboard rather than a regular one? I'm not too skilled in soldering as of yet, but would anyone happen to know the pro's and con's of each?

 

[mdjensen22]

Solderless is easier to reuse components when you're done with your circuit.

 

[MATLABdude]

Definitely go for the solderless variety--reusable, pretty reliable and fairly durable. Something like the MB104, 106 or 108:
http://www.circuittest.com/Data/CTCAT-45.pdf

The perfboard is handy for permanent / semi-permanent work. PRO-TIP: If you ever buy some, get the ones with copper, either in extended traces or just around the holes: the fact that you can solder them and easily attach components properly is worth way more than the extra buck or whatever you save.

The story goes that they're called breadboards because they're amongst the lower-cost components you have, and you'll go through them about as frequently (I'm still on my originals, FWIW--don't plug really warped and worked component leads / wires in them, and don't over current them and they'll last quite a while). You can buy 'refills' or naked breadboards as well (ones without the backing and terminal jacks):
http://www.circuittest.com/English/Content/Items/MB-102.asp

As for your question about Radio Shack, they've gone downhills a long ways from the halcyon days when the sales guys were all knowledgeable (it started out as a place for ham radio / DIY electronics guys), and components were plenty. Then again, that was the rep when *I* was going through undergrad, too (and that was nearly a decade ago).

 

[mattbrrtt]

There are a number of places online to purchase items to help breadboard your experiments. Here are a few of the electronic suppliers that I have used.
http://www.allelectronics.com/
http://www.digikey.com/
http://www.mouser.com .
http://www.alliedelec.com/

 

[Peavey]

Thank you all for the replies and advice. More than likely I will have more questions in the nearby future. Thanks again.

Peavey

 

[Peavey]

Not sure whether or not to post a new topic or just bump this week-old thread. Regardless, I have some news. My grandfather (an electrician) gave me an "Electronics Learning Lab" which is quite useful. I was following the tutorials and schematics included in the lab, and then my grandfather would give me tests. He said "You can follow the schematic, and that's awesome; however, in order to actually learn the circuitry, I'm going to be giving you a few random quizzes throughout the weekend. Once you are able to take apart the circuit and make it your own - that's when you really start learning (and having fun)." For example, I was following this schematic that showed me how to connect 4 LED's to 4 buttons - 1 LED per button. His quiz was for me to connect all 4 buttons to 1 specific LED.

Anyways, onto the news: I figured out my LED circuit I described in the first post. I used the solderless breadboard that came with the kit, and plugged in 3V to a switch, that led to a 3V green LED and back to ground. Let me just say that even though it was a simple task, I legitimately felt like Victor Frankenstein, haha. Now, all I'm "assuming" I have to do is find a AA battery holder, use the wires from the kit and the switch and LED and I completed the task I wanted to do. However, it may or may not be simple. Anyways, I wanted to thank you all, and now I'll be needing to practice my soldering.

Thanks,

Peavey

 

[MATLABdude]

Your grampa sounds like a pretty good teacher!

Despite what I said above, RadioShack will probably have that 2-AA battery holder. If not, it's nothing some stripped wires (buy a wire stripper if you don't already have one, and save your nails / teeth / knife) and a little electrical tape can't help you with.

Good luck, and have fun with it!

 

[Peavey]

Thanks, and wow, I didn't even think of using electrical tape. Is it safe to solder the stripped wires right on to the positive and negative terminals of the batteries though?

P.S. Is there anyway else of securing the batteries/switch/and LED other than screwing it in? I've seen a few LED holders at RadioShack, however, would that be of any use to me?

Peavey

 

[MATLABdude]

I'd be a little hesitant of soldering leads onto batteries--remember, you're heating up a can of caustic paste to a not-inconsiderable temperature! The large metal area may also make it difficult to properly solder, and exposure to high temperatures will reduce the capacity of alkalines. You can buy ones with leads / tabs soldered on, but these are usually spot welded. Beyond that, you have to do that for every battery you get (unless these are rechargeable ones--again, high temperatures may affect capacity)

My toolbox includes a hot glue gun--quite useful sometimes when you're trying to cobble stuff together in a semi-permanent fashion (along with maybe some sand paper to roughen up surfaces)

 

[Peavey]

Alright, so. I had tried the electric tape method to tape the stripped ends of the wire to the terminals on the batteries. It kept falling off or coming loose. So, I just decided to run out to RadioShack and pick up a AA battery holder. Sadly, I found an enclosed 2 AA battery holder, however, the project I'm working with isn't going to fit if I use it. So, I picked up a 1 AA holder, and had to get a 1.8V LED, instead of my 3V that I was using for two. The LED I'm using now is a bit dim, however, it still lights up. Laugh if you may, but the project I've been trying to do is lighting up my Nerf Maverick. I thought'd it be not only fun, but a challenge. So I attached a very quick schematic I drew up on a picture of the innards of a Maverick. I'm thinking that after attempting to fit everything in there, I may as well just buy a project kit and mount it on there. Question is, would anyone happen to know how I could mount it on plastic without it becoming extremely bulky? Would this where the hot glue gun be of use?

Also, another quick question. I've seen that AA and AAA (and possibly a few others) have a voltage of 1.5V. MY question is, is why do they both have 1.5? I've seen a 6V and 9V battery, of course, but if I'm using 1 AA, why couldn't I use 1 AAA if they are the same voltage? Is it because of the amps? Was the AAA made for a smaller size convenience? Haha, sorry for the bombarding questions, this question has been pestering me for quite a while.

Peavey

 

[b.shahvir]

Yes it is for the Amps. AAA can source lesser amps than AA due to less size and higher internal resistance. Low power devices generally are smaller in size due to it's area of application.

 

[MATLABdude]

[...]Question is, would anyone happen to know how I could mount it on plastic without it becoming extremely bulky? Would this where the hot glue gun be of use?

Also, another quick question. I've seen that AA and AAA (and possibly a few others) have a voltage of 1.5V. MY question is, is why do they both have 1.5? I've seen a 6V and 9V battery, of course, but if I'm using 1 AA, why couldn't I use 1 AAA if they are the same voltage? Is it because of the amps? Was the AAA made for a smaller size convenience? Haha, sorry for the bombarding questions, this question has been pestering me for quite a while.

Peavey

Sorry to be so long in replying...

You could probably tape/glue this onto the outside (barrel or handle--if it works for regular ammunition / gun, it'll probably work for a NERF gun!) Applied judiciously, electrical tape sometimes works. Frequently, it doesn't (due to vibration / movement preventing good electrical contact). Sometimes, it works against it (due to the conductors being separated by a layer of adhesive). The battery holder? Wherever you can squeeze the weight in, and run wires from.

Why 1.5V in an alkaline cell? That's the potential in the particular chemistry of the cell you're using. 6V and 9V batteries use 4 or 6 cells in series. Note that NiCD and NIMH batteries (different chemistries) are slightly lower than these nominal alkaline voltages, usually around 1.2-1.3V / cell when fully charged
http://en.wikipedia.org/wiki/Alkaline_battery

AAA (and even AAAA--usually in hearing aid systems) were built for lower capacity, but smaller size, as you surmise. The downside is that (for a given brand and chemistry) they'll cost more per battery than AAs.