Instructables
Picture of EMF Detector Kit
This is my submission to the Kit Contest. This device will react to almost all EMF's depending on the strength of the field and the type of wire used for the inductor. this will detect lightning, some radio frequencies, the field around the human body, the field mde by rubbing PVC pipe on cotton cloth and the Electrostatic field around Tesla Coils. (dont shock this project with lightning, Tesla coils or static because it will destroy the transistors)

Step 1: Parts and Tools

Parts:
     2N 3904 NPN transistors X4
     2N 3906 PNP transistor X1
     connecting wire (if you make it on a solderless breadboard)
     8-Ohm speaker
     a 5V-9V power supply that connects to a wall adapter!!! this is very important!!!
     a breadboard (soldered or otherwise)
     a coil of magnet wire (dimensions don't really matter. the size only affects amount of interference they receive)
Tools: 
     Soldering iron
     solder
     pliers
     wire cutters/strippers 

Step 2: Schematic

Picture of Schematic

Step 3: Kit on at Breadboard

Picture of Kit on at Breadboard
This is the alterable form of this project. if you wish to leave it at this to allow for changes, by all means, do so. if you want a more permanent form, please continue.
mfredrick12 months ago
Nice but one question.. What is the range of the sensitivity?
I like your bio. I'm same way.
Tesla is the best.

I think I'm going to give this circuit a try, but why does it need to be attached to a wall adapter? Is a 9v battery not enough?
toast5678 (author)  transistorguy2 years ago
no, it will work with a 9v battery, but it will only be sensitive to high-energy EMF's such as those from a Tesla Coil. If you plug it into a 9v wall adapter you will receive much more interference (which can be tuned out) but will be more sensitive to low-energy EMF's. The voltage drain is minimal though, if that is what you were asking. also, i'm glad we share the same views on Tesla.