Noisy LEDs (And We’re Not Kidding!)

David Merrill discovers unintended sound effects from an LED display:

“I didn’t realize that an LED could make *audible* sound until my friend/colleague Sajid called me over to have a look. What can I say – it’s true.. This is a circuit with NO SPEAKERS, making audible sound.

Watch (er, listen) to the video.

4 Comments

1. 
   Andrew
   March 12, 2008

   .. as opposed to *inaudible* sound?

   reply
2. 
   Steve Winder
   March 12, 2008

   I wonder if the noise is coming from ceramic capacitors (piezo electric effect) or from any coils in the circuit?

   reply
3. 
   Doug Allender
   March 13, 2008

   That would have been my guess, I have often seen this with very cheap switchmode psu designs, when the current is modulated.

   reply
4. 
   Chris Halford
   March 11, 2009

   >
   Er, yes! Do you find ultrasound iritating?

   reply