Electromagnetic Field

Well then, good luck hunting down parts :).

In my case, it's about 3 meters.

I'm not sure about the range in meters (I didn't do any measurements on an open field), anyway it has plenty of range for my needs :).

Hi there, I think that the coils used in these types of modules are part of an RF circuit, and while they seem to work on a small distance without an antenna, they do have a much better transmission with an added antenna.

Hi there, thanks for checking out my instructables (I saw your comment on my photophone instructable), and also thank you for recommending me this company, (I didn't know about them).Thanks for great comments :).

Thank you :)

I didn't realize that my speaker already had a tweeter built in lol, thanks for commenting :).

Thank you very much :)

Simply replace an LED with a laser diode, everything else stays the same.

Thank you :)