Aaron built an electromagnetic field detector using an Arduino board, 3.3MΩ resistor, LED, and wire –
I was messing around with my Arduino board and figured out how to make a cheap portable electromagnetic field (EMF) detector. It only requires a led, 3,300,000 Ohm resistor, and wire. As I approach an EMF the led gets brighter, so I can locate the source. Messing around with the code and resistor values I can change the sensitivity of the device; when I first made the EMF detector I could only find one place to stand in my apt where it didnt go off. I am working on getting a commercial EMF detector that spits out quantitative values so I can calibrate my version and have it do the same on a LCD screen.
Another crazy-simple yet fun Arduino project – anyone out there have an “official” EMF detector for comparison/calibration?
In the Maker Shed:
Make: Arduino
12 thoughts on “Simple EMF detector with Arduino”
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Love it.
30 seconds of build and a lot more of fun.
I put two of these circuits on my arduino, and I’m going to see if I can get useful directional data. EMF antennae for my bot!
I’ll see your two circuits and raise you one for a 3 axis rig!
Have you posted the code? If not, can you do so?
Very simple and elegant!
Hey I was pretty surprised to see my video up on the Make Blog. It is pretty exciting! I got the idea while making an electronic art project, you should check out that YouTube video http://www.youtube.com/watch?v=k4cYpf9zwkg. Anyways the code is pretty simple, I was going to add an averaging function for the input values so the led dims more smoothly; sometimes it flickers instead of dims. Just copy and paste the code below into the Arduino coding environment. It looks like you will have to clean up a bit of the formatting when you copy and paste it into the Arduino environment, pasting code in this forum distorts the spaces of I put in the comments.
// Aaron ALAI EMF Detector April 22nd 2009 VERSION 1.0
// aaronalai1@gmail.com
// *future note, put in averaging function to average val which should result in a more
// smooth response from the led
int inPin = 5; // analog 5
int val = 0; // where to store info from analog 5
int pin11 = 11; // output of red led
void setup() {
Serial.begin(9600);
}
void loop() {
val = analogRead(inPin); // reads in the values from analog 5 and
//assigns them to val
if(val >= 1){
val = constrain(val, 1, 100); // mess with these values
val = map(val, 1, 100, 1, 1023); // to change the response distance of the device
analogWrite(pin11, val); // *note also messing with the resistor should change
// the sensitivity
}else{ // analogWrite(pin11, val); just tuns on the led with
// the intensity of the variable val
analogWrite(pin11, 0); // the else statement is just telling the microcontroller
// to turn off the light if there is no EMF detected
}
Serial.println(val); // use output to aid in calibrating
}
Curses, the period for the YouTube link got into the URL.
More info can be found at my budding website aaronalai.com
My thoughts watching the first 5 seconds of this video – “oh neat…no NOT THE SOCKET NO NO…oh, good!”