Introduction: ATTiny EMF Detector
As is tradition, finished product image first.
Inspired from masteruan's similar build, which I will link below, I set off to build my own micro sized Electro-Magnetic Field Detector. The goals were to make this as small as possible while retaining enough stability that it would not break in someone's pocket. The challenge to that was the antenna. As you can see from my finished picture, I decided to use the protoboard to help the antenna keep its shape, which I believe it does marvelously.
Masteruan's build: Attiny85-EMF-detector
Step 1: Parts
[1x] Atmel ATTiny85V microcontroller and socket
[1x] 3.9M Ω resistor
[4x] LEDs (Colors many vary)
[Various] Jumper wires
[1x] Push button or switch
[1x] Button cell battery and holder
Step 2: Coding and Testing
Upload the code to the ATTiny85, instructions for this can be found all over the internet so refer to one of those if you've never worked with a "raw" microcontroller before.
Build the project on a breadboard to test the wiring before moving onto the protoboard. This step is probably the most important as its much more difficult to fix when the project is already soldered to a board.
As my code changed very little, and you'll most likely have to trouble shoot a few things yourself, I've attached the original Github code link here: Github
Step 3: Prep the Antenna
Coil the antenna to the desired shape. This can easily be done by wrapping a section of wire around a pencil then stretching it to a good length. What is a good length you ask? Well as you know from asking such a great question, the wire length will affect the frequency it pick up. However, since we are not looking for a specific frequency and instead are basically looking for any electrical noise, the length is not crucial to the build. I simply used a spare wire that held it shape when coiled.
My wire happened to be slightly larger than the protoboard's holes, so I drilled out the ones it was to pass through.
Step 4: Organize
With the largest component in place, the antenna, I decided where to place the rest of the parts. Wanting the strength LEDs up near the front, I placed those then worked backwards in such a way that (I thought) the ATTiny would be easy to wire in.
Step 5: The End
With everything in place, it was an easy solder job to finish. My project was not originally going to use a push button, just battery removal for power on/off. But I decided to add one after, as you can see by the stacked board at the bottom. I reused some scrap wire that had used shrink wrap on it, so I decided to waste not and use that too. It helped insulate my bad wiring job from shorting out.
Step 6: Things to Change
If I were to rebuild this project, I would firstly change the layout. Opting to place the button cell on the bottom of the board so the button can be on top. In such a way that he wires are organized better. Or specifically design a pcb for it. Maybe change the button for a switch so I don't have to hold it on. Perhaps use a 3D printed cover for the bottom half to cover the electronics.