From: scientist77017@gmail.com   
      
   On Wednesday, May 22, 2019 at 5:11:37 AM UTC-5, default wrote:   
   > On Tue, 21 May 2019 19:33:42 -0700 (PDT), AK   
   >  wrote:   
   >   
   > >On Monday, May 20, 2019 at 10:04:35 PM UTC-5, default wrote:   
   > >> On Mon, 20 May 2019 18:04:36 -0700 (PDT), AK   
   > >>  wrote:   
   > >>   
   > >> >On Monday, May 20, 2019 at 4:48:52 PM UTC-5, default wrote:   
   > >> >> On Mon, 20 May 2019 12:20:32 -0700 (PDT), AK   
   > >> >>  wrote:   
   > >> >>   
   > >> >> >I got this, but saw no polarity markings like my other larger piezo   
   buzzer.   
   > >> >> >   
   > >> >> >Andy   
   > >> >> >   
   > >> >> >Piezo Transducer   
   > >> >> >Electrical Specifications:   
   > >> >> >   
   > >> >> >    Rated Voltage: 5Vp-p   
   > >> >> >    Rated Current: 2mA (max)   
   > >> >> >    Sound Output at 10cm: 85 dBA   
   > >> >> >    Resonant Frequency: 2.04kHz   
   > >> >> >    Dimensions: 8.43mm H x 12.1mm diameter   
   > >> >> >    Number of pins: 2   
   > >> >> >    Pitch: 6.5mm   
   > >> >> >    Lead thickness: 0.62mm   
   > >> >> >    PC mount   
   > >> >> >    Markings: 12RT04CC   
   > >> >>   
   > >> >> It is not a buzzer, it is a transducer.   
   > >> >>   
   > >> >> A transducer is a device that can convert (in this case) sound to   
   > >> >> electricity or electricity to sound.  To use that as a buzzer you will   
   > >> >> need to drive it with an oscillator, at 2.04 kilo hertz and a wave   
   > >> >> with a 5 volt peak to peak amplitude (to get the maximum noise out of   
   > >> >> it)   
   > >> >>   
   > >> >> It doesn't have the polarity indicated because it has no polarity.   
   > >> >> Think of it as a loudspeaker (another transducer since they can be   
   > >> >> used as microphones and convert sound to electricity)   
   > >> >>   
   > >> >> It will work at other frequencies with less volume.  It should click   
   > >> >> when you put a battery on the leads, and click again when you reverse   
   > >> >> the polarity of the battery.  (it also stores a charge like a   
   > >> >> capacitor)   
   > >> >>   
   > >> >> Look up oscillators if you want to use it as a buzzer.  The 555 makes   
   > >> >> a dandy oscillator.   
   > >> >   
   > >> >Ok. I want to replace the current piezo buzzer I have with something   
   that will fit on my breadboard.   
   > >> >   
   > >> >It's a pulse type which I do not like.   
   > >> >   
   > >> >Andy   
   > >>   
   > >> I like bells myself.  I cut a chime bar from some hard aluminum alloy   
   > >> and used a solenoid to pull down on a mallet to strike the bar.  It   
   > >> sounded bad (with all the mechanical noise the solenoid made) and I   
   > >> ended up using a 555 as a monostable timer to get just the right   
   > >> timing on the stroke of the mallet.   
   > >>   
   > >> I hate piezo buzzers.  Even a speaker driven with a 555 sounds better   
   > >> to me.   
   > >   
   > >What specs do I need to look for the speaker?   
   > >   
   > >My circuit runs from 9 vdc.   
   > >   
   > >Andy   
   > Any small speaker should work.  There's dozens of paper cone speakers   
   > in a 2-3" size that make good annunciators.  If you have a junk radio   
   > you can cannibalize a speaker from it.  I'd use 8 ohms or higher would   
   > be my choice if I was buying one.  You would also need/want an   
   > electrolytic cap of 10-100 uf to use in series with it to keep DC off   
   > the speaker.   
   >   
   > http://www.circuitdiagram.org/morse-code-practice-oscillator-using-555.html   
   > http://www.cranburyscouts.org/ElecOsc.htm   
   > http://www.circuitdb.com/?p=254   
      
   Thanks.   
      
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