You should know that there are a large number of tutorials online for ways to make a handheld EMP (electromagnetic pulse). They will disrupt electronic devices in your vicinity and would be very useful if masked men approach you and try to photograph you with a potentially illegal biometric collection application. If made correctly they are harmless to people, and if made incorrectly they are most likely harmful to the operator. It is a non-violent defense device.
Ah, well, they don’t need to worry about being caught or identified, they can just stop you in the street. I thought you were referring to scammers or something.