Parallax Part # 900-00001 Piezo Speaker can this be used with a LM386 Need T

sam_sam_sam

·Will this work or do I·need to use some thing else

·Here is the Link to it ...>>>>> ··· ·Piezo Speaker·



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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 4/11/2010 1:01:43 AM GMT

Leon

You'll probably get more noise out of it by connecting it to an MCU output pin, as it won't match the LM386 output impedance. Drive it from two outputs in anti-phase to increase the output.

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Leon Heller
Amateur radio callsign: G1HSM

sam_sam_sam

Drive it from two outputs in anti-phase to increase the output.

And how would you do this Please give an Example

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··Thanks for any··that you may have and all of your time finding them

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Sam

Leon

Connect it to two outputs and make one high and the other low, alternatively. It increases the voltage across it. You can also drive it with a transistor from a high voltage supply.

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Leon Heller
Amateur radio callsign: G1HSM

PJAllen

someone said...
in anti-phase to increase ...
It increases the voltage across it

Oh ??
If an output pin is 5V or Gnd, you've still only those potentials.· Anti-phase, anti-matter, anti-clockwise, or maybe this is about XMOS?· That's it, it's the XMOS Factor; yeah, Stamps don't do that.

Leon

You are correct, of course. I was thinking of bipolar drive which is often used with high-power ultrasonic transducers. Piezo devices are much louder when used with XMOS chips than with Parallax products, of course.

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Leon Heller
Amateur radio callsign: G1HSM

Post Edited (Leon) : 4/11/2010 2:36:29 PM GMT

PJAllen

You can use a 555, astable, and make a "voltage doubler"; it's a voltage multiplier, the capacitor-diode step-up ladder thing (more stages, rungs, more voltage [noparse][[/noparse]!!] - it could be a shocking experience.)· Take a look at the attached circuit, it's from a Ray Marston article.

I say that the same thing could be done by sourcing the oscillation from a Stamp output pin.· "What's the frequency, Kenneth?"

[noparse][[/noparse]Sorry, sam_sam_sam, but this Subject may go sideways from hereon.]

PJAllen

In fact, I guarantee this.

And then I thought: Cool, kV; a Stamp-based shock-wand ("taser") in Completed Projects.

Post Edit -- How about that little somethin'-somethin' for your BoE-Bot?

Mike Green

Back when the Propeller was new, Beau (I think it was him) posted a boost regulator using a Propeller output (and an input for feedback) like the 555 doubler above.

PJAllen

Well, from the values given, it's a fairly square square wave, 54%, at about 3700 Hz.·
Smaller caps (multiplier)·mean a shorter (faster) charge-up time, but less current (ampere-seconds), too.·

Post Edit --
Capacitors should be rated WVDC > final output voltage, and the diode PIVs, too, say I.

' you're using the PBASIC PULSOUT ckt
'
' PAUSE is 1msec incr., we need to deal
' with faster times
 
DO
 PULSOUT pin, 68            ' 68 * 2us = 136 usec HI
 FOR useful_delay = 0 to x  ' x = as many times = 135usec
   a = a + 1                ' something that does nothing
   NEXT
 ' you have to burn time, appx 135usec.  PULSOUT does the
 ' HI time and "useful delay" FOR..NEXT does the LO time
LOOP

Post Post Edit -- I should have started another Subject, but then I'd have to do all the work.· Sorry.

OK, if anyone is interested in the "HV" aspect, I've started a new Subject --
http://forums.parallax.com/showthread.php?p=897801


Post Edited (PJ Allen) : 4/11/2010 7:22:26 PM GMT

Beau Schwabe

The boost circuit really isn't going to help with a piezo unless you are into the 50V and above range.

Here is a link where I posted something several years ago on how to drive a piezo...

http://forums.parallax.com/showthread.php?p=464410

...for 3.3V drive, substitute the 4.7K resistors with 3.3K resistors.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 4/11/2010 5:53:24 PM GMT

sam_sam_sam

·Beau Schwabe

·Posted 8/21/2004· ·>>>>>

Typically when you use a piezo, one terminal is connected to a microcontroller, while
the other terminal is connected to ground. When the pin goes HIGH, the piezo is deflected in one direction producing a
"click"...when the pin goes LOW, the piezo relaxes producing another "click". By using an inverter you can effectively
deflect the piezo in each direction past center creating a noticable increase in volume.


How do you· write this in·code
Can you Please give me an example

If I went with an LM386 chip to do this where would I find a very small round·speaker that would be able· to handle 1.25 watt of power
a web link please

Thanks for any help that

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··Thanks for any··that you may have and all of your time finding them

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Sam

Phil Pilgrim (PhiPi)

You can probably do more acoustically to amplify the piezo than with most of the easier electrical solutions. Get some shrink tubing with a big enough diameter to fit over the piezo's plastic body. Cut it about an inch and a half long, and shrink it over the piezo, so it forms a snorkel. Drive the piezo, and start cutting little bits of the shrink tubing off the end. It should get louder, then begin to diminish. When this happens, stop cutting. It may help to use a drill bit or metal rod that's a hair smaller than the piezo to do the tube shrinking. That way, you can increase the length of the larger diameter inner chamber.

This technique is what I used for the design of the SoundPAL:



It took a lot of experimenting to get it right, but made a huge difference in the volume level and audio "fullness" produced by that tiny speaker. Eventually, I made a mandrel over which the shrink tubing could be formed in a production environment. It not only sets the length of the inner chamber, but also keeps the inner diameter of the snorkel from closing too far when shrunk:



-Phil

sam_sam_sam

I want to thank·everyone who has reply to this post

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··Thanks for any··that you may have and all of your time finding them

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Sam

T Chap

I have a product that needs a loud beep, this is the circuit used below with a 386 that creates a much louder beep than just with the Prop pin alone. Works great. Frequencies used range from 500 to 4000. VCC is 5volts on the 386.

Not sure how different this part is, but here is the buzzer that is used in the schematic. search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=102-1269-ND&x=0&y=0

Post Edited (Todd Chapman) : 4/14/2010 6:57:29 AM GMT