Attiny 45 EMF Sensor





Introduction: Attiny 45 EMF Sensor

About: I like finding new uses for things, making things, and improving things. I'm a student who is currently looking for a better job, one where I can make an actual difference.

This sensor is very sensitive and can pick up electrical signals from anything that uses power. It displays the amount of interference it picks up by sequentially lighting 4 led's one after the other. I have tested it all around the house and its been kinda fun to see how different things compare. It can also be used to follow house electrical wiring inside the walls, yes its that sensitive.

Step 1: Program the Attiny 45

I used an Arduino Nano to program the Attiny 45 it was easy to setup and worked great. The code shown reads the analog input and uses that information to figure out how many led's should be on if any. The values at which each led lights up are dependent on the antenna, its resistance to ground, and the attiny's input sensitivity. These values will have to changed in the code to best match your personal setup. Sensitivity is adjusted by increasing or decreasing the resistance to ground on the antenna and by changing the led turn on values.

Step 2: The Circuit

Start by connecting one of the Attiny 45's analog inputs to the antenna then ground it using four 1 mega ohm resistors in series, after that wire the remaining outputs to light four led's. I used a solid copper wire for the antenna and wrapped it around a marker to get the spring like coil. It seems to work fine with 3 volts, so I used a AAA battery holder to power it. I recommend building it on a breadboard initially so you can see what works best for your antenna and modify the circuit or code as necessary.

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Hi! Sir, im from philppines and i like the design of your emf. Can you help me sir how to make an emf step by step. If its ok with you sir. Thank you!

You find my design here with instructions how to program the Tiny on my web site

5 replies

I don't have an arduino. Let me ask you this, I want to create a table that is an Ouija board but instead of using the planchette, the letters light up when the spirit gets close to it, Is there a way to make these little detectors for this project? There are 26 letters, a yes, a no and hello and good bye. 30 in all. Can you help me make something like this?

From my disgussion group:

The words/answers on an Ouija board are controlled by someone in the group moving their finger onto an answer that makes sense. If you hook up some EM/RF/Geiger sensors to a bunch of lights it will never output anything other than random noise. You would also need a mic or something to trigger when a "question" has been asked by the group, otherwise it would just be a constant stream of flashing letters. Could have an arduino wired up with some pre-programmed words ( maybe a list of names / places / relevant words could be loaded in via bluetooth from a phone? ) and then a mic to pick up when there is silence (i.e. after someone asked a question) and then it would light up letters from a randomly selected word stored on the arduino.

This can be done, perhaps with an Arduino Mega that has 52 pins. I just wonder how you want it to trigger. What makes the lights change? Spirit alone is not logic to a micro controller. Perhaps in the software a random seed generator. I would charge $ 1000 for a project. Your best option is to join a local Hacker group. They do not hack your PC. They are programmers, electronics engineers, hobbyists found on all over the globe who help each other to make things. hacking means to them taking things apart and make something else out of it. I am on the Gold Coast QLD if you like to join our group.

Which Arduino Mega should I purchase from There are several. I'll get one of those and the UNO

I may take you up on that offer of a $1000.00 if I can't figure it out. I know what hackers are, I do that with old stuff and try to repurpose them when possible, have a little electronics experience and want to learn more. As for triggering the LED's, I'm thinking EMF disturbance to trigger the light at each letter. Maybe a tone too. Making 30 of the instructable you have here was what I was thinking but doesn't seem practical if using batteries as a power supply. The circuits have to be separate so each letter lights individually when the field is disrupted around that individual letter. How hard is it to program the chip and what's the difference between the UNO and MEGA? I was going to buy them online but not sure which to get. Why the MEGA? Gold Coast? Austrailia? A bit far from me but I'd love to join. At 56, it's time for a new hobby. So I'll do that. As for programming the Mega, could you tell me how to do that or do an instructable for a simple board that I could expand on? I think starting small and adding to it would be smarter than making a huge board at once.


We made an arduino with 16 shift registers that can turn on 128 lights. The problem remains "I'm thinking EMF disturbance to trigger the light". I will do more research, but my discussion group can not help with your trigger idea so far.

I started with an Freetronics starter kit cat.No.XC4262 from Jaycar 3 years ago. But best is to join a group to learn, exchange ideas and ask all your questions. Youtube also has many tutorials.

You can find my web link in here

Can you share the process for programming the ATTiny45 using the Arduino Nano? I guess specifically how you did it. I have an Uno but I am assuming it requires additional shields or something for the 8 pin chip. Thanks and neat design.

2 replies

I followed an instructable on here, search program attiny with arduino. Uploaded by randofo. All you need is a breadboard or a way to connect to the pins on the attiny and a 10uf capacitor.

Sorry for the late replies, I haven't been getting emails telling me when I receive comments.

Nice design. I like the simplicity of it. I made one with an ATtiny85 and it works just fine.

No current limiting resistors needed with a 3Volt input. Simple but working software. The chip is a available on eBay or Element 14 in AUS. Good work keep it up.

1 reply

Hi, I'm wondering what the antenna is made out of, could you please give me the requirements for this instructable?

1 reply

The antenna is made of solid copper wire, similar to the kind used for doorbell wiring. All that's required for this project is : attiny 45 or similar micro controller capable of running arduino code, 4 LEDs, 4 1megaohm resistors, 3volt power source, 8" solid copper wire.

/*EMF detector instructables

written for ATiny 85

2 October 2015

improved code by by Robert Moller


void setup (){






int val=0;


void loop(){

int val = analogRead(A3);

int del =30;

delay (1);

if (val>0 && val<=4){ digitalWrite(4,HIGH);

delay (del);}

if (val>=4 && val<= 6){ digitalWrite(0,HIGH);

delay (del);}

if (val>=6 && val<=8){ digitalWrite(1,HIGH);

delay (del);}

if (val>8){ digitalWrite(2,HIGH);

delay (del);}



digitalWrite (4,LOW);

digitalWrite (0,LOW);

digitalWrite (1,LOW);

digitalWrite (2,LOW);



1 reply

Thanks, for the updated code

Hii. i am 11TH class student and want to make emf sensor for exhibition. can you please tell me from where i get that chip with 8 pins.