Seeing radio waves with a light bulb (Diana Eng)

June 25, 2010 at 00:18 1 comment

This amazing and super simple radio receiver translates radio waves into light. It is a dipole antenna, made with two pieces of wire connected to a flash light bulb. The transmitting antenna will induce some current in the receiving antenna and it will force the current up and down (alternate current) turning the light bulb on proportionally to the signal strength.

I wasn’t actually really able to achieve the same result with coding, Xbee and Arduino… hahaha

From the Make Blog by Diana Eng:

Using a low power amateur radio transmitter and a simple light bulb receiver circuit, we see how radio waves and electromagnetic induction transmit energy and signals wirelessly through the air. We also see how dipole and Yagi antennas radiate their energy in different patterns. Read on to build your own dipole receiving antenna!


I made the light bulb detector with some materials I had laying around my apartment: a flash light bulb, a chopstick (wooden dowel), wire, tools to solder, hair ties (zip ties work too). You can easily make one too. But make sure that you comply with all safety regulations when you play with your light bulb detector. More information on RF exposure safety is available here.

1. Solder small pieces of wire to the terminals of the light bulb.

2. Basically you are using wire to make a dipole antenna for the light bulb. Use this calculator to find the length of the wires for your dipole antenna by entering in the frequency. The value for the quarter wavelength is the length of each wire (you may need to cut off an additional half inch from each side).

3. Solder the antenna wire to the light bulb wires and secure everything to the chopstick to keep it straight using your hair ties/zip ties/glue gun.


Entry filed under: Prototyping, Related Projects.

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