The Light Modulator

$72.50 inclusive of GST

  • Transmit sound from your phone on a light beam
  • Make light audible, speak on a sunbeam, and produce a laser show
  • Demonstrate cutting-edge fibre optics communication, molecular kinetic theory & persistence of vision
  • Teach serious physics: Amplitude modulation,  AC vs DC, and the Inverse-square law

North American Orders: Please order from Educational Innovations



Out of stock

Category: SKU: E02


This has to be one of the most engaging classroom light demonstrations!

How to transmit sound from your phone on a visible light beam . . .

  1. Plug the torch into your mobile phone’s ear phone socket
  2. Activate the solar panel connected to a pre-amp and speaker
  3. Play a song on the phone and the sound will ride the light beam to the solar panel. Very cool!
Watch the video    —->
The phenomenon is known as Amplitude Modulation (AM), the same as the AM on your radio!  You now have the ability to transmit sound (information) on a carrier (light) beam!   We have fine-tuned and re-designed this technology into this easy-to-do kit for all science teachers and science demonstrators.  All you need is your mobile phone and you’re ready to amaze.

What is in the kit?

  • A flashlight transmitter
  • A solar panel receiver with amplifier & speaker
  • USB cable to charge the speaker
  • Bulb-shaped flickering LED light
  • Flickering RGB ball
  • Sugar beads, mirror and clear jar
  • Instruction sheet with 10 Demos you can do in your classroom

Required (not included):  2 x AA batteries (not rechargeable); 3 x AAA batteries;  sound sources such as a mobile phone or MP3 player.

The kit reviewed online

Dr Kevin McComber
Dr Kevin McComberSpark Photonics, USA ---
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"It has been immensely helpful to our project in helping students (and teachers, and parents) literally see how light can carry information. We just used it with 18 middle and high school teachers and they were blown away.”
Chris Ward
Chris WardSenior Physics Teacher , Ivanhoe Grammar School, Melbourne
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“Thanks for the chance to try out the new light modulator kit. It created some of the best WOW moments I have had in my Physics classroom for a long time. In the past I have used electronics boards, a photodiode and a phototransistor to teach modulation but this was always limited to the reliability of the connections. The ease with which this kit is able to be set-up and operated is fantastic. This is an excellent kit, and the demos are all worth showing”

How does this happen?

The light beam is modulated.  Everyone knows about the AM and FM on their radio.  AM being amplitude modulation and FM, frequency modulation.  The radio uses radio waves as carrier beam but visible light waves can do the same, as all are electromagnetic waves and therefore can be ‘modulated’ to carry information.

Modulation is the changing of the amplitude or frequency of a wave so it is in synchronisation with the variations of a second signal. The carrier wave simply carries the information superimposed on it by the information signal.  Its waveform undergoes a change – it gets “modulated” with the information signal.
The image on the right gives an indication of how AM works.

The sound signal can be from any electrical audio source. The variable sound signal is fed into the light (carrier) signal, and the intensity (or amplitude) of the light beam changes so it reflects the information from the sound signal.  These flashlight changes are minute but are detected by the solar panel which in turn mirrors its output to the same pattern.

The sound signal is virtually riding on the back of the carrier beam and goes wherever the carrier beam goes! 


Instruction sheets

PDF File   (4 MB)

Receiver On / Off Switching Information

How to adjust the output Volume 

Additional information

Weight0.5 kg