EMF or Electromagnetic forces are basically present where there is a presence of electricity(electrons/charge..).
If a copper wire is made to carry a charge even it will generate an electromagnetic field.
Here we will try to make a sensor that senses strong EMF's like the ones in our walls(mains ||200-250 volts)
Step 1: Why Make One ?
Sometimes its good to be safe and take precautions while handling high voltage electronics.
This device can detect the presence of charge and hence will be a useful tool
Step 2: Things You'll Need
1-Some BC 547 transistors (I preffer 3).
2-An output source(like a buzzer).
3-1000 ohm resistor
Step 3: About the BC 547
Basically its an NPN transistor
NPN is for negative positive negative .
Step 4: Steps -
1-place one 547 on the bread board flat side facing forward.
2- place another one in front of the previous one in a way that the middle pin of the first one is connected to the first pin (from the right) of the second transistor .The middle pin of the second transistor should not be connected to any pin .The third pin in each case should have a common connection point.
3-do the same with any number of transistors (i personally prefer a maximum of 5)
4-place your output source on the bread board and give it positive
5-give the first pin of the first transistor (only) negative .
6- connect the second terminal of the output device to the common connection (third pin of all transistors)
7-test it out by placing it near any operational main connection
8-connect a wire to the middle pin of the final transistor and place it in the air (this will catch the EMF signals)
If its working there will be an interference in the output
Step 5: Warnings-
-I will not advice the use of an LED because the current flow drastically increases and hence there is a chance that it might burn.
-Use a buzzer instead.
-Don't put the signal catching wire into the main's holes !!!!!!
-this device drains a lot of battery