Author Options:

How to send and receive an electrical signal? Answered

I don't know much about radio waves and oscillator circuits , AM/FM and stuff, but I need to send just electrical signals wirelessly, without any information on it, to some other device which activates when it would detect the signals. I would prefer to make the devices myself, if it is possible, without needing to buy anything, like RF oscillators and other stuff. 

  I was told that whenever electricity passes through a wire, a radio wave is emitted outwards from the wire, and is emitted every time the current flow stops, starts or changes direction,

 I was also told that whenever a radio wave crosses a wire, it induces a very small current in it.

I don't know if whether the above information was correct or not but I think I can use it in making such a device.



5 years ago

Build a spark gap transmitter (Google it), they're easy to build and they work. Oh, and learn Morse code.

I have a simple home made buzzer, it has an electromagnet which continuously attracts a metal strip and then lets it go back and produces many sparks, I also observed some disruptions in radios if I brought them near to it, can I use it as the transmitter?

And how will I make the receiver?

You could build a simple circuit consisting of a flashlight, which acts as your TRANSMITTER. Then the receiver could be just a solar cell or cadmium cell wired to turn on a 2n3904 transistor. The output of the transistor could turn on a motor or a small light or even a relay that could power something like a table lamp. When you shine the flashlight onto the solar cell... it turns ON the transistor which turns ON the relay.... which clicks down and turns ON the table lamp. The table lamp should be BATTERY powered 12 volts if this is your first project because you shouldn't be messing with mains-power as a beginner. This simple setup would be succeptable to INTERFERENCE or undesired operation if the sun shined on it or if the room was too bright it would trigger ON the circuit. This could be solved by placing a small piece of black pipe around the solar cell. Now only the DIRECT light from the flashlight will trigger the solarcell, not other lights. Do you need a schematic of this?

The receiver would be moving and changing direction so this won't work.