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Best method of beeper for the Prop — Parallax Forums

Best method of beeper for the Prop

James LongJames Long Posts: 1,181
edited 2008-03-18 01:02 in Propeller 1
Ok.....so I'm working on a project, and need it to beep.

The beeps are going to be pulsed depending on condition.

What is the best method to do this? Also, I would like to have a very simple interface with the Prop.

Piezo Buzzer, or piezo transducer?

Power and space are limited so share your thoughts.

James L

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James L

Partner/Designer
Lil Brother LLC (SMT Assembly Services)

Post Edited (James Long) : 3/18/2008 12:09:56 AM GMT

Comments

  • Graham StablerGraham Stabler Posts: 2,510
    edited 2008-03-17 23:39
    There was a thread by computer guy on this I think, you can drive piezo sounders direct from the prop, best loudness by driving differentially, this can be done with the counters too.

    I need to do this too so I know when a fly flies through my laser trigger.

    Graham
  • James LongJames Long Posts: 1,181
    edited 2008-03-18 00:07
    Graham,

    I did a little search....and found differential driving is a fair bit louder by what was posted.

    I figure this is for a non-driven piezo (spelled it wrong the first time).

    I wonder what specs would be required of the piezo. Vp-p....max volt....min volt.....etc.



    James L

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    James L

    Partner/Designer
    Lil Brother LLC (SMT Assembly Services)
  • RaymanRayman Posts: 14,813
    edited 2008-03-18 00:25
    Another way to go is to play an 8-bit wav file...· This could be small enough to fit in RAM and you could make it sound anyway you want...

    http://www.rayslogic.com/propeller/Programming/dac/dac.htm

    ·
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2008-03-18 01:02
    The older mobile phones (cell phones) always sound louder than the newer polyphonic phones because they applied maximum pulse power to the transducer whereas playing a wav file implies that it the overall volume and efficiency is reduced. Also, the piezo transducers really love to resonate and when you select the right frequency for the transducer it sure is a lot lot louder. So drive them differentially at their resonant frequency (around 3-5kHz depending). Most piezos are spec'd at 10 volts, are happy to run up to 20 or 30 volts, and are usually run at much lower voltages.

    You can also drive them single ended with an npn with a small inductor in the collector to supply and then connect the piezo from the collector to ground. The inductor gives a nice "kick" to the piezo making it a lot louder than would be possible at lower voltages.

    BTW, do you know that because it is a transducer not only can it produce sound it can also detect sound? At least as a shock/knock sensor if not more. Morse code your settings by tapping on the case! Actually I can do something similar now using 4 indicator leds dual-purposed as my Vkey keypad (as long as I'm not in the dark).

    *Peter*
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