Hi, I'm new to electronics. I was going to get a breadboard and start screwing around but decided to go with the Arduino since I'm in the computer field and wanted to have something interface with my PC. Anyway, when my board finally arrives, I'm going to start slow and learn as I go along. You know, make some LED's blink and what not. However, I'm kinda confused on what a shield is. The kit I ordered comes with a proto shield and I assume that just allows you to stick a breadboard on top of the Ard. What about motors? I have few RC car motors that I was thinking of lighting up. Do I need a motor shield for that? Is there a good beginner doc I can read that covers these types of questions. Thanks! I look forward to this hobby.
Hi,
I'm quite a noob myself to electronics and Arduino, but I have learned a few things by now and I'll try to answer your questions the best I can. Hope you'll excuse me if I'm wrong about some things.
Here is a link to a beginners manual that may be of use to you:
www.earthshinedesign.co.uk/ASKManual/Site/ASKManual.html
An Arduino shield is basically any board that you can attach on top of the Arduino. Some of them are specialized into a specific task (eg. an Xbee shield or motor shield). A protoshield is a protoboard (NOT breadboard) that plugs into Arduino allowing you to expand Arduino with your own homemade SOLDERED circuits. Like this:
Attaching a mini solderless breadboard to the protoboard isn't really what it's for, but I guess you could do that.
I haven't had experience with driving dc motors (only servos) but I know it's possible. The PWM I/O ports (there are 6 of them) can be used to do this. There are off course several things to consider here like the voltage required by the motors (Arduino only supplies 5 or 3.3 volts) and if you're using several motors you'll have to use an external power source, since there is a limit to how much the Arduino can pull.
The manual I linked to also shows you how to hook up a DC moter (in project 11).
That's all I can provide...from one noob to another... 
Thanks for the info and the link to the pdf. Will come in handy. Thanks for answering my shield question. May as well share a few links that I stumbled upon tonight:
http://itp.nyu.edu/physcomp/Tutorials/Tutorials
http://www.tigoe.net/pcomp/code/understanding-electricity
Thanks!
You're quite welcome.
And I forgot to add this link:
www.arduino.cc/en/Main/ArduinoShields
And here are a few other general electronics links that I've found useful:
I make my own shields, you can too if you are handy with a small drill:- http://www.thebox.myzen.co.uk/Hardware/Arduino_Sheld.html
Aniss, I was looking thru the PDF guide you sent and I noticed that the diagram in the first project shows an LED being connected to a resistor but the resistor was connected to the breadboard between the LED's cathode (-) side and ground on the Arduino. Is that correct or does it matter? The instructions just say connect everything like it is in the picture. I thought the resistor should sit between the 5v positive and the LED anode..
Its stuff like this that make things confusing for noobs. Something as straight forward as lighting up an LED with a resistor. >:(
and if you're using several motors you'll have to use an external power source, since there is a limit to how much the Arduino can pull
Even a small little $1 hobby motor draws a few amps in a stall and at least an amp running free. The Arduino I/O lines can handle 0.04 amps. So even the tiniest motor will need external driver circuitry (like a motor shield).
I noticed that the diagram in the first project shows an LED being connected to a resistor but the resistor was connected to the breadboard between the LED's cathode (-) side and ground on the Arduino. Is that correct or does it matter?
This is where it does help to start with a basic foundation in electronics. The purpose of the resistor in that case is to limit the current flowing through the LED, and current is constant in a series circuit. So in that case it doesn't matter which side of the LED the resistor is on.
Thanks Oracle. I guess I need to figure out how to build a motor shield then.
In terms of the resistor/LED example, my thinking was following the flow of electricity out from the positive. In which case it hits the LED first without going thru the resistor. Still not quite clear on why it wouldn't matter. I agree that knowing more of the basics would help me but can you explain this or point me to a resource that explains it. Please correct my way of thinking. Electricity is flowing out the 5v, thru the LED anode, out the cathode and into the resistor and onto ground. Why would the resistor not have to sit between the LED and 5v? Please help me visualize what you mean when you say current is constant in the circuit as that's what's causing my confusion.
By constant current, I mean the current through each component is the same (in this case, the current through the LED equals the current through the resistor).
Look up "Kirchhoff's Current Law" for a good explanation.
LEDs when they're on are effectively short circuits, they allow as much current through as the rest of the circuit will supply, so you need something else to control the flow of current. In this case it's the resistor which is subject to Ohm's law.
I find h-bridges to be useful in driving motors. You can use an external power source, run motors in either direction, and use pwm to adjust speed.
Oracle, I'm still not getting it. The fact that the current is constant or equal across all components kinda makes sense but what I'm still stuck on I guess is my way of thinking of the voltage and the current. I'm visualizing volts or current coming out the battery or powersource, traveling thru the LED and then hitting the resistor. I still need an explaination for why the LED wouldn't blow with the resistor on the other end of it if the current is coming out the 5V and hitting the LED before the resistor. That's where I'm stuck. I guess I need to understand the effects of current vs voltage maybe for starters but I think I'll get it once it's explained to me in this example. Sorry to be such a noob but I think once I understand this I'll be over a major hurdle in my understanding of all this.
I've learned that current is like water, volts is like water pressure, etc but I must still be missing some basic concept and I'm really tring to understand this.
Hi again,
Sorry for the slow reply. No time.
And again I'm not really the guy to ask about electronics. A few months ago I barely knew what a circuit was. I'm a programmer (now studying computer science) who recently ventured into the wicked world of electronics and microcontrollers so that I can build robots to experiment with that which REALLY interests me: Artificial intelligence!!
I was also somewhat confused when I first noticed the resistor came AFTER the LED in the circuit of project 1. But I have come to understand what Oracle tried to explain you earlier. I'll try to explain it my way. Perhaps it works better from noob to noob
When you place a resistor in a circuit it limits the flow of electricity in the ENTIRE circuit. Not just the part of the circuit following the resistor (=between the resistor and the ground) as you seem to think. Therefore it has the same effect placing the resistor before or after the LED in the given example.
But again I'm not entirely sharp on the subject. In the manual it states that the resistor is there to lower the VOLTAGE (=the SPEED of the electrons), while Oracle says it's used to control the flow of CURRENT (=the QUANTITY of electrons), which also confuses me a bit. Off course these are interrelated (read: Ohm's law and Kirchhoff's law), but how that works on a practical level still puzzles me somewhat. But I'm learning new stuff every day and that's all I can ask for.
Looks like both you and I still have quite a bit of researching, studying and expermenting to do ... 
ah you made a post while I was writing...let me know if my explanation seems more eatable...
Although I hate to see or hear it, the best analogy to get this concept is the flow of water.
You can relate the flow of water through a hose to the flow of electricity through a circuit.
Flow of water (volume) == current
Pressure == voltage
If you constrict the hose (add a resistor to a circuit) you reduce the flow of water through the hose. After adding constrictions you will reduce the pressure at the end of the hose.
A site that puts it in much better words than I can is:
There are many differences between electricity and water in this crude and often used example. You can use this analogy only so far. If this makes the concept seem more logical to you then great. If not keep reading about electronics.
Please abandon this analogy and move forward with the study of electronic circuits not water flow and don't try to come back to this after learning more about electronics. 
A nice site begin with is:
It is in sequential order starting with volume 1 and has practice problems (you need to understand basic DC circuits before moving on to AC circuits and components)
Looking at two resistors as a "voltage divider" helped my understanding at first. You may want to look closely at that.
In a series circuit the current is the same value at any point in the series circuit no matter how many components are wired in series. It's Kirchhoff's current law.
There is also a Kirchoff's voltage law for a series circuit that states that the sum of the individual voltage drops across all series components will equal the total source voltage applied to the series string.
Make sense?
http://www.knowledgerush.com/kr/encyclopedia/Kirchoff's_Laws/
Lefty