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.
We have a be nice policy.
Please be positive and constructive.
Is that really a 3.9 M Ohm resistor? and how many watts? I'm wanting to build this myself, but don't want to purchase what I don't need.
This all looks very neat - nice!
Could this be easily modified to make an EM interference detector?
I'm sure that some light switches in my mother's house are 'dirty' and causing spikes in the circuit and blowing the bulbs - it'd be handy to have a small device I could hold next the switch and check for interference when I turn it on and off
I don't think that is very likely. The main reason lamps fail is excessive heat. That could be the result of excess voltage but that is not really likely either. More likely is lamps that are too powerful for the fitting, or poor quality fittings. Either way, if there is insufficient ventilation the lamps will become too hot and fail prematurely.
Another reason lamps fail is turning them on an off too often, the thermally induced heating and contracting of the filament causes too much stress. Maybe your mother is trying to save power by switching on when entering a room and off when leaving. A false economy in some instances. Best is to replace with LED lamps as the old ones fail.
I agree - which is why I replaced the original multiple halogen light fitting with a multiple LED one a couple of years ago - but they have still been dropping like flies
I have sourced my LED bulbs from numerous places and not just the cheap ones - yet they still blow too frequently - 2 a month!
Yes it could be a dodgy light fitting - but that is new and the light switch is very old and I think a 'dirty' switch is my next most likely cause.
The reason I want to test it without replacing it is because the light switch is actually grouted into place and removing it will leave a mess I don't want to have to deal with unless I have to.
That is basically what it is already. EM interference is just signal noise caused EM fields that you don't want. Any type of EMF is what we are detecting here. So would this detect EMinterference? Yes. Is it going to be reliable enough to detect a fault in a wiring system? Most likely not.
Thanks for the reply - I will have to think of another way to do that then