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Topic: Can I generate DTMF through a Piezo speaker (Read 2197 times) previous topic - next topic

beachdog

I see the Melody tutorial that show how to play a tone of specified frequency through a Piezo, but what about if I need to play dual tones simultaneously.....like DTMF tones.  Is that going to be possible with a Piezo?  As a newbie there is much I don't understand, but it seems like since the Piezo is connected to a single pin I don't see how I can generate a tone that includes two frequencies.

TchnclFl

I'm pretty sure you'd need 2 piezos running at the same time to generate a dual tone.  :-/

retrolefty

The latest version of the Tone library supports generating DTMF on board and there is an example sketch showing how:

http://code.google.com/p/arduino-tone/source/browse/trunk/examples/DTMFTest/DTMFTest.pde

However, I don't think a  Piezo is the best choice for DTMF as piezos tend to be pretty peaky in their frequency response. You would probably be better off using a very small dynamic speaker (with a series current limiting resistor), say like this on:

http://www.allelectronics.com/make-a-store/item/SK-230/20-MM-32-OHM-SPEAKER/-/1.html

Lefty

TchnclFl

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The latest version of the Tone library supports generating DTMF on board and there is an example sketch showing how:


Wow!  And here I was thinking that DTMF required two piezos/speakers  ::)..

retrolefty

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Wow!  And here I was thinking that DTMF required two piezos/speakers  


Oh course not, otherwise we would all have to be wearing stereo headphone for your telephone conversations.  ;)

Lefty

TchnclFl

Fair point :P.  I guess I never gave it much thought? :)

beachdog

Thanks so much for the quick and helpful answer!

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