RF project

[Curious010]

Hi all,

Can any one direct me to a site or supply me with a simple circuit that can demonstrate how I can use radio waves to generate electricity from a small distance (I am talking 20-30 cm), I know this is possible but I am not sure how to go about it.

My thinking is use a transmitter that outputs a relatively high energy radio wave and a receiver that has an aerial with a fairly large surface area in order to pick up as much energy as possible, and use this energy to power some kind of indicator.

Any suggestions will be greatly appreciated

Regards

Curious

 

[Mikebits]

The only thing I can think of is a field strength meter.
Here is a link, I did not look at the circuits to see if they work though.
http://www.discovercircuits.com/F/field-strength.htm

 

[stevez]

A number of years ago I set up a demonstration for my kids. At one end of a room I put an oscilloscope and probe connected to a coil of wire. At the other end of the room I ha another coil of wire and a D battery (1.5 volts). I'd connect/disconnect the battery/coil by just scratching the wire against the battery - the scope responded and displayed a representation of the voltage induced in the coil.

You might take it a step further. You could make a crystal radio - if you are "allowed" to state that noise heard in the earphone demonstrates the voltage resulting from the RF. You might then use an automotive ignition coil - or just use a lawnmower - you should hear the pops (RF) generated by the spark. It's my understanding that current flow thru a diode (see rf noise bridge) generates a lot of RF but I do not know if there's sufficient power for the demonstration you desire.

Radio Shack books have some simple transmitter/receiver circuits - more or less generate and hear clicks.

Good luck.