Sorry for the late response. I can’t actually closely read this huge comment as I don’t have the time or incentives but I can try to help a little:

I am not sure you have your physics correct. It sounds like you are trying to build a distance sensor by measuring the change in frequency of light? I can’t tell what you are talking about? My advice, if you are actually trying to measure the relative distance of an object, is best to get a sensor designed to do so:

http://www.acroname.com/robotics/info/articles/sharp/sharp.html

There are plenty of examples online on how to use these with Arduinos.

As for your circuit problems. Noise control depends on the noise’s source. It could be the power supply, in which case you should use decoupling capacitors. Or it could be from the signal itself, in which some kind of RC filter could be used:

http://en.wikipedia.org/wiki/RC_circuit

You mentioned a pin floating when trying to read it. This is sometimes caused by not setting the pinMode correctly http://arduino.cc/en/Reference/PinMode ? Who knows though.

With the rest of your problems, I can’t help you. There is only so much circuit debugging I can do through reading a comment in a blog post.

One more piece of advice, if you want help from an engineer or programmer, NEVER mention that it is for school!! We have a bad history with people asking us to do their homework o_0

Good Luck

So now that you know my skill level, here is where I’m at:

1) Im not asking for any full programs (seeing as this is an independent study) just a line or two to help guide me.

2) I am writing a program to send out a range of frequencies b/t 34000 and 38000 to determine the distance of an object. A read of 34000 = object close to emitter and receiver, and a read of 38000 = object far from emitter and receiver. I had no problem doing this on a parallax board. But here is my delimmas using Arduino:

A) I cant find any code out there to at least guide me on properly emitting out of a transmitter (there is a ton about reading in a signal from a remote but I don’t need to do this). Currently, Im using the tone command right now and can see that Im sending out signals by looking through my camera phone and it is working, but is this a reliable way to emit a signal?

B) I am using a Radioshack ir receiver 276-640 and its not receiving any of my tone pulses. Im using an LED to determine if the input is high or low and it is reading that it is always high (no input). I’ve played with the delays b/t output signal and input read, and the duration of tone pulses (tone(pin, frequency, duration)) and still not getting any signal.

Heres my latest code:

const int ledPin2 = 2;
const int irSensor = 9;
const int delaytime = 100;
int irLed = 3;
int sensorstate = 0;

void setup(){
pinMode(ledPin2, OUTPUT);
pinMode(irSensor, INPUT);
pinMode(irLed, OUTPUT);
}
void loop(){
tone(irLed, 38000, 50);
delay(delaytime);
sensorstate = digitalRead(irSensor);

delay(100);
if (sensorstate == HIGH){
digitalWrite(ledPin2, HIGH);
delay(delaytime);
}
if (sensorstate == LOW){
digitalWrite(ledPin2, LOW);
delay(delaytime);
}
}

(yes delaytime = 100 is to long but Ive tried many other delays and still nothing)

question 2 is why cant I read an input signal? My wiring is correct though Im positive.

C) I understand that there is noise floating around, but generally, what is the best way to eliminate it?

D) This one has got me to the point of typing this msg. I’ve spent roughly 85 hours so far with the Arduino board and I have digitally and analytically read inputs with ease. Now all of a sudden with the program posted above I am receiving some crazy inputs. First off, I think I may have fried my board due to me soldering a wire onto my old IR receiver and fusing the insides together. One of the leads on the IR receiver broke so I soldered a wire to it. When I plugged it into the board, the tiny chip (relay Im assuming, I dont know) next to the USB B female jack got EXTREMELY HOT real fast. Yes, a short. This is how I know my wiring is now correct b/c when I played with the wiring for my soldered IR receiver every configuration made that little chip get REALLY HOT, so I did a lot of online research to make sure I was correct. The little chip has gotten really hot roughy 5 times.

I’ve sense replaced my ir receiver with the Radioshack 276-640.

But now (back to the crazy inputs) Im experiencing something really goofy. After a few hours of tickering around with wires I have found that my pins are acting crazy. For example, say I have switch cases for digitalRead(pin9, HIGH) or digitalRead(pin9, LOW), I can have a wire plugged into pin 9 (which is pin9) and nothing else (The other end just floating aimlessly into the air). Yet, when run the program and I move the wire around (I found this out by accident of course) my LED light that displays HIGH or LOW flickers. Sometimes the read is HIGH, sometimes the read is LOW. What is going on?!!! Is the wire receiving ambient signals alone?? Ive repeated this process on another pin (pin and the same thing happens. Have you ever heard of a pin receiving input just through a wire alone or is my board shot? This is why I brought up the question about noise earlier, am I getting noise? Or again, is my board fried?

Besides this independent study I’m currently doing, I have thought of many ideas I could use the IR transmitter and receiver for and I would be very grateful for your input.