Post by thread:[EE]: Piezo buzzer question, how to connect it

Hi. I bought a couple of little piezo buzzers to use with my pics. But I'm not sure exactly how they are supposed to work! The buzzer (no datasheet) is a round copper colored flat disc about 1.5 cm in diameter. One side is all metal and the other side has a 1.25 cm diameter flat whitish disc on the back, very thin, in the middle of the main metal disc. In the middle of the white disc is soldered a 3 cm red lead. Has anyone any experience with these? Thanks, Lindy --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

if it only has 2 leads, you probably connect one to positive and one to negative, obviously i'd try red positive first. if it has 3 leads, you need a feedback circuit to drive it (these aren't very common). if it's just a piezo transducer and not a buzzer, you'll just get a click unless you send it a more interesting waveform than just turning it on. Lindy Mayfield wrote: > > Hi. I bought a couple of little piezo buzzers to use with my pics. But I'm not sure exactly how they are supposed to work! > > The buzzer (no datasheet) is a round copper colored flat disc about 1.5 cm in diameter. One side is all metal and the other side has a 1.25 cm diameter flat whitish disc on the back, very thin, in the middle of the main metal disc. In the middle of the white disc is soldered a 3 cm red lead. > > Has anyone any experience with these? > > Thanks, > Lindy --------- -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

It only has 1 lead! (-: I've tried with a PWM wave. If I plug the positive red lead to the output pin and touch a negative wire to the smooth, shiny backside, it buzzes nicely, I think. > > if it only has 2 leads, you probably connect one to positive and > one to > negative, obviously i'd try red positive first. if it has 3 > leads, you > need a feedback circuit to drive it (these aren't very common). > if it's > just a piezo transducer and not a buzzer, you'll just get a > click unless > you send it a more interesting waveform than just turning it on. > --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> It only has 1 lead! (-: > I've tried with a PWM wave. > If I plug the positive red lead to the output pin and touch > a negative wire to the smooth, shiny backside, it buzzes nicely, I think. You can get twice the voltage and about 4 times the power out of one of these by driving them with two pins with signals on them in anti-phase. When A is up B is down and vice versa. This can make the difference between low & OK output levels. An interesting caution. When using these directly connected to a processor pin NEVER tap them sharply. They act as voltage generators when mechanically excited and a tap can generate enough energy to destroy a processor ;-(. Some designs have failed when a piezo which is mounted inside a box has been subject to a severe shock. The technology is essentially the same as used in piezo fire lighters. I've never heard of anyone using a fire-lighter as a speaker, but ... :-) RM -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> I've tried with a PWM wave. If I plug the positive red lead to the > output pin and touch a negative wire to the smooth, shiny backside, > it buzzes nicely, I think You'll probably find it has a resonant frequency, at which it will be very noticeable. I have some invulturated from greeting cards and they vary from 1.6kHz to around 4kHz. These types are likely to have a low voltage rating, maybe 4-5Vrms. Others can have up to 20+Vrms across them (not the DC-operated ones, they go to about 30VDC and have oscillator circuitry built in) You can improve the volume by suspending it in mid-air as best as possible. A piece of double-sided tape on the brass side for example If the one wire you have is soldered to the white ceramic side, do try to keep that connection. They are buggers to re-attach -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> An interesting caution. When using these directly connected to a processor > pin NEVER tap them sharply. > They act as voltage generators when mechanically excited .. Yes, they can be used as input sensor (push switch), although you must apply a "shock" pressure, with some mechanical help ( fingertips are to soft ). A light hit with a peace of wood or a pencil can generate more than 5 volts with ease, but of coarse for a very short moment. If mounted under glass or pvc it works too, make sure that the pressure is applied around or besides the solder blob, to prevent cracking of the coated area. So, an input actuator with audio feedback is what this can be. If manual actuation is wanted, then add an opamp with 1000x gain (or more). At van Wijk. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> > An interesting caution. When using these directly connected to a processor > > pin NEVER tap them sharply. > > They act as voltage generators when mechanically excited .. > Yes, they can be used as input sensor (push switch), although you must apply > a "shock" pressure, with some mechanical help ( fingertips are to soft ). > A light hit with a peace of wood or a pencil can generate more than 5 volts > with ease, but of coarse for a very short moment. If mounted under glass or > pvc it works too, make sure that the pressure is applied around or besides > the solder blob, to prevent cracking of the coated area. YMMV. Voltage achieved will depend on the piezo used, rate of tap and more. Also very much on impedance delivered into. As noted, direct into a pin can be fatal without something to damp and limit the waveform. If you have an oscilloscope available, try this with direct connection to the scope probe alone (typically 1 Mohm , 10 pF). Compare this to capacitance of a bare PIC pin. RM -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Don't forget these need a lot of voltage. I have a bunch of the 3 lead kind and you can run it with one lead, but you get low-moderate noise at 20 volts. Lindy Mayfield wrote: {Quote hidden}> It only has 1 lead! (-: > > I've tried with a PWM wave. If I plug the positive red lead to the output pin and touch a negative wire to the smooth, shiny backside, it buzzes nicely, I think. > > >>if it only has 2 leads, you probably connect one to positive and >>one to >>negative, obviously i'd try red positive first. if it has 3 >>leads, you >>need a feedback circuit to drive it (these aren't very common). >>if it's >>just a piezo transducer and not a buzzer, you'll just get a >>click unless >>you send it a more interesting waveform than just turning it on. >> > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

If I understand correctly from what I've so far read, then the answer is that it only needs one lead, but I just need more juice. I'll try plugging it into the wall socket, see if I get a 50 Hz buzz. Thanks to all who answered on this. > Don't forget these need a lot of voltage. I have a bunch of the > 3 lead > kind and you can run it with one lead, but you get low-moderate > noise at > 20 volts. > --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Yow! Don't plug it into the wall socket! You'll get a buzz all right, and a bang too! -- Lawrence Lile Lindy Mayfield <spam_OUTLindy.MayfieldTakeThisOuTEUR.SAS.COM> Sent by: pic microcontroller discussion list <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> 06/16/2004 12:03 PM Please respond to pic microcontroller discussion list To: PICLISTKILLspamMITVMA.MIT.EDU cc: Subject: Re: [EE]: Piezo buzzer question, how to connect it If I understand correctly from what I've so far read, then the answer is that it only needs one lead, but I just need more juice. I'll try plugging it into the wall socket, see if I get a 50 Hz buzz. Thanks to all who answered on this. > Don't forget these need a lot of voltage. I have a bunch of the > 3 lead > kind and you can run it with one lead, but you get low-moderate > noise at > 20 volts. > --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I'm always surprised how few people (especially newbies) ever go right to the source for information on these things. A google search would turn up many manufacturers of piezo buzzers. They virtually all have applications notes and theory of operations on their web sites. The internet (and Google or your favorite search engine) is your friend! I would suggest visiting Murata Erie, AVX and Kyocera web sites. THese are all manufacturers I've used in the past and they have quite a lot of technical data and application information available online. Also, many distributors like Digikey have data sheet links for the prodcucts they sell as well as links to the manufacturers web sites. This makes finding information even easier and faster. (trying to politely and non-offensively say find and RTFM... ;-) Matt Pobursky Maximum Performance Systems On Wed, 16 Jun 2004 11:54:14 +0200, Lindy Mayfield wrote: {Quote hidden}> It only has 1 lead! (-: > > I've tried with a PWM wave. If I plug the positive red lead to the output pin and touch a negative wire to the smooth, shiny backside, it buzzes nicely, I think. > > > > > if it only has 2 leads, you probably connect one to positive and > > one to > > negative, obviously i'd try red positive first. if it has 3 > > leads, you > > need a feedback circuit to drive it (these aren't very common). > > if it's > > just a piezo transducer and not a buzzer, you'll just get a > > click unless > > you send it a more interesting waveform than just turning it on. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

You know, I did a google search for piezo and I couldn't find anything. I did however search on piezo element instead of buzzer. I personally found information on piezo to be a tad sparse. Matt Pobursky wrote: {Quote hidden}> I'm always surprised how few people (especially newbies) ever go right > to the source for information on these things. A google search would > turn up many manufacturers of piezo buzzers. They virtually all have > applications notes and theory of operations on their web sites. The > internet (and Google or your favorite search engine) is your friend! > > I would suggest visiting Murata Erie, AVX and Kyocera web sites. THese > are all manufacturers I've used in the past and they have quite a lot > of technical data and application information available online. > > Also, many distributors like Digikey have data sheet links for the > prodcucts they sell as well as links to the manufacturers web sites. > This makes finding information even easier and faster. > > (trying to politely and non-offensively say find and RTFM... ;-) > > Matt Pobursky > Maximum Performance Systems > > On Wed, 16 Jun 2004 11:54:14 +0200, Lindy Mayfield wrote: > >>It only has 1 lead! (-: >> >>I've tried with a PWM wave. If I plug the positive red lead to the output pin and touch a negative wire to the smooth, shiny backside, it buzzes nicely, I think. >> >> >>>if it only has 2 leads, you probably connect one to positive and >>>one to >>>negative, obviously i'd try red positive first. if it has 3 >>>leads, you >>>need a feedback circuit to drive it (these aren't very common). >>>if it's >>>just a piezo transducer and not a buzzer, you'll just get a >>>click unless >>>you send it a more interesting waveform than just turning it on. > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Wed, 16 Jun 2004 09:12:57 -0700, Shawn Wilton wrote: > Don't forget these need a lot of voltage. I have a bunch of the 3 lead > kind and you can run it with one lead, but you get low-moderate noise at > 20 volts. There is an old trick for getting much higher volumes out of piezo transducers (especially at low battery voltages like 1.5V~3V) I learned almost 20 years ago. It's also shown in many applications notes for these devices. Basically it works like this: 1. Find the capacitance of the piezo device, almost always listed in the spec sheet. 2. Calculate the devices capacitive reactance at the frequency you will be driving the device. 3. Calculate an inductor value for the equivalent inductive reactance. 4. Place an inductor of said value in parallel with the piezo device. 5. Drive the whole parallel piezo/inductor circuit with a FET/transistor rated ~10x higher voltage than your voltage source. What you're doing is making a resonant tuned circuit that will generate a much higher driving voltage for the piezo buzzer at the tank circuit's resonant frequency. This is the method used for wrist watches and other devices that may run off, for example, Lithium button cells. You can also determine the inductor value empirically by trial and error, although calculating the value will get you much closer much faster. I once had to generate a VERY loud piezo warning beep for an electronic pill bottle (medication reminder) that ran on a CR2032 button cell. The circuit described above generated ~20Vac drive voltage to the piezo and was extremely loud. We also used a tuned chamber (acoustic resonance) to augment the output. Matt Pobursky Maximum Performance Systems -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Wed, 16 Jun 2004 09:12:57 -0700, Shawn Wilton wrote: > Don't forget these need a lot of voltage. I have a bunch of the 3 lead > kind and you can run it with one lead, but you get low-moderate noise at > 20 volts. You can greatly augment the acoustic output of piezo devices by edge mounting them (this keeps mechanical damping to a minimum). Most piezo manufacturers sell PCB mounting clips that hold them by the edges and provide electrical contact especially for this purpose. You can also greatly increase the acoustic output by mounting the piezo element in a tuned (resonant) enclosure. This is why many piezo buzzers are sold in plastic cases. The case itself holds the piezo element by it's edge in an enclosure tuned to it's resonant frequency. I wouldn't consider myself a piezo buzzer expert, but I've used almost every type I have seen in dozens of applications over the past 25 years. Most of this information is available from the manufacturers directly. Matt Pobursky Maximum Performance Systems -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

But you have to know the manufacturer to begin with. All the ones I picked up were from surplus and there's no indication of manu. Matt Pobursky wrote: {Quote hidden}> On Wed, 16 Jun 2004 09:12:57 -0700, Shawn Wilton wrote: > >>Don't forget these need a lot of voltage. I have a bunch of the 3 lead >>kind and you can run it with one lead, but you get low-moderate noise at >>20 volts. > > > You can greatly augment the acoustic output of piezo devices by edge > mounting them (this keeps mechanical damping to a minimum). Most piezo > manufacturers sell PCB mounting clips that hold them by the edges and > provide electrical contact especially for this purpose. > > You can also greatly increase the acoustic output by mounting the piezo > element in a tuned (resonant) enclosure. This is why many piezo buzzers > are sold in plastic cases. The case itself holds the piezo element by > it's edge in an enclosure tuned to it's resonant frequency. > > I wouldn't consider myself a piezo buzzer expert, but I've used almost > every type I have seen in dozens of applications over the past 25 > years. Most of this information is available from the manufacturers > directly. > > Matt Pobursky > Maximum Performance Systems > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

C'mon Shawn, have a little resourcefulness... ;-) If you look at datasheets for a variety of physically similar devices, you'll see that they all have specs in the same basic range for capacitance and resonant frequency. This is basic physics, they're all made from the same materials using the same basic process. You can always find the resonant frequency by driving the piezo element with an external signal generator and listen for the loudest frequency. You can also measure it by putting a small resistor in series with the piezo and look for the largest voltage drop across the piezo element -- this will be it's resonant frequency. It really doesn't take very long to characterize a given piezo element, even if there are no markings on it at all. Matt Pobursky Maximum Performance Systems On Wed, 16 Jun 2004 11:10:51 -0700, Shawn Wilton wrote: {Quote hidden}> But you have to know the manufacturer to begin with. All the ones I > picked up were from surplus and there's no indication of manu. > > Matt Pobursky wrote: > > > On Wed, 16 Jun 2004 09:12:57 -0700, Shawn Wilton wrote: > > > >>Don't forget these need a lot of voltage. I have a bunch of the 3 lead > >>kind and you can run it with one lead, but you get low-moderate noise at > >>20 volts. > > > > > > You can greatly augment the acoustic output of piezo devices by edge > > mounting them (this keeps mechanical damping to a minimum). Most piezo > > manufacturers sell PCB mounting clips that hold them by the edges and > > provide electrical contact especially for this purpose. > > > > You can also greatly increase the acoustic output by mounting the piezo > > element in a tuned (resonant) enclosure. This is why many piezo buzzers > > are sold in plastic cases. The case itself holds the piezo element by > > it's edge in an enclosure tuned to it's resonant frequency. > > > > I wouldn't consider myself a piezo buzzer expert, but I've used almost > > every type I have seen in dozens of applications over the past 25 > > years. Most of this information is available from the manufacturers > > directly. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

actually, i think it's best to support them in a couple of places around the outer edge. also, conductive epoxy fixes the problem of trying to solder to things that are hard to solder. i'll be getting some slightly flexible conductive epoxy soon and repackaging it in roughly 1 gram kits for about $3 ea. (i'll know for sure after it's done), should you need some and if you can wait a while. the epoxy is also good up to 450 deg F and the flexibility makes it nearly stress free. good stuff, i just wish i didn't have to repackage it. Jinx wrote: {Quote hidden}> > > I've tried with a PWM wave. If I plug the positive red lead to the > > output pin and touch a negative wire to the smooth, shiny backside, > > it buzzes nicely, I think > > You'll probably find it has a resonant frequency, at which it will > be very noticeable. I have some invulturated from greeting cards > and they vary from 1.6kHz to around 4kHz. These types are likely > to have a low voltage rating, maybe 4-5Vrms. Others can have > up to 20+Vrms across them (not the DC-operated ones, they go > to about 30VDC and have oscillator circuitry built in) > > You can improve the volume by suspending it in mid-air as best > as possible. A piece of double-sided tape on the brass side for > example > > If the one wire you have is soldered to the white ceramic side, do > try to keep that connection. They are buggers to re-attach -------- -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Ah, see I didn't know any of that. Not to mention I've never been able to find a datasheet for this particular type of element. Trust that I've done some searching, just never turned anything up and I had to move on. But since it's been brought up, might as well beat the horse till it drops, right? Matt Pobursky wrote: {Quote hidden}> C'mon Shawn, have a little resourcefulness... ;-) > > If you look at datasheets for a variety of physically similar devices, > you'll see that they all have specs in the same basic range for > capacitance and resonant frequency. This is basic physics, they're all > made from the same materials using the same basic process. You can > always find the resonant frequency by driving the piezo element with an > external signal generator and listen for the loudest frequency. You can > also measure it by putting a small resistor in series with the piezo > and look for the largest voltage drop across the piezo element -- this > will be it's resonant frequency. > > It really doesn't take very long to characterize a given piezo element, > even if there are no markings on it at all. > > Matt Pobursky > Maximum Performance Systems > > On Wed, 16 Jun 2004 11:10:51 -0700, Shawn Wilton wrote: > >>But you have to know the manufacturer to begin with. All the ones I >>picked up were from surplus and there's no indication of manu. >> >>Matt Pobursky wrote: >> >> >>>On Wed, 16 Jun 2004 09:12:57 -0700, Shawn Wilton wrote: >>> >>> >>>>Don't forget these need a lot of voltage. I have a bunch of the 3 lead >>>>kind and you can run it with one lead, but you get low-moderate noise at >>>>20 volts. >>> >>> >>>You can greatly augment the acoustic output of piezo devices by edge >>>mounting them (this keeps mechanical damping to a minimum). Most piezo >>>manufacturers sell PCB mounting clips that hold them by the edges and >>>provide electrical contact especially for this purpose. >>> >>>You can also greatly increase the acoustic output by mounting the piezo >>>element in a tuned (resonant) enclosure. This is why many piezo buzzers >>>are sold in plastic cases. The case itself holds the piezo element by >>>it's edge in an enclosure tuned to it's resonant frequency. >>> >>>I wouldn't consider myself a piezo buzzer expert, but I've used almost >>>every type I have seen in dozens of applications over the past 25 >>>years. Most of this information is available from the manufacturers >>>directly. > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

On Wed, 16 Jun 2004 11:31:08 -0700, Shawn Wilton wrote: > Ah, see I didn't know any of that. Not to mention I've never been able > to find a datasheet for this particular type of element. Trust that > I've done some searching, just never turned anything up and I had to > move on. But since it's been brought up, might as well beat the horse > till it drops, right? Indeed! :-) http://www.mps-design.com/misc-images/deadhorse2.gif Seriously though, I did try to include most of the useful information I've learned over the years and pass it on to others who may not have any practical experience with piezo elements. I can be a bit surly at times (part of getting older I guess... ;-) but I am really a generous and helpful guy at heart. I just get irritated when people don't put much effort into learning things for themselves (I'm not talking about you in this case, I mean in general). I have very little time or patience for people that fall into that category. Matt -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> I'm always surprised how few people (especially newbies) ever go > right > to the source for information on these things. A google search > would > turn up many manufacturers of piezo buzzers. They virtually all > have > applications notes and theory of operations on their web sites. > The > internet (and Google or your favorite search engine) is your > friend! I agree with you. And I apologize if my question lead to the belief that I didn't search before asking the group. I've had these buzzers for a couple of months now, and I did search for how to use them, but found nothing (or found nothing I could comprehend). My ignorance may be in recognizing a buzzer with a one-wire only lead from the web search results. I may have found the answer but it was buried in a schematic that wasn't obvious to me. Which is why I asked the group. Thanks to all who answered. (-: Cheers, Lindy --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> Seriously though, I did try to include most of the useful > information > I've learned over the years and pass it on to others who may not > have > any practical experience with piezo elements. I can be a bit > surly at > times (part of getting older I guess... ;-) but I am really a > generous > and helpful guy at heart. I just get irritated when people don't > put > much effort into learning things for themselves (I'm not talking > about > you in this case, I mean in general). I have very little time or > patience for people that fall into that category. > > Matt > I'm also very generous at helping people, and I too get frustrated when people don't make the effort that I think they should. For example, I will do a lot to help a person learn something, but I draw the line when I think they are trying to get me to do their work for them. (The fish or teach a person to fish deal.) One of the favorite things I do in my job is teach beginners MVS, an IBM mainframe operating system. This keeps me humble. The burden is on me to know and understand the information well enough to be able to convey it to others, especially beginners, no matter their learning style. Some people need things explained in words, some need to see it, some need to actually do things with their fingers (on the keyboard), or perhaps some combination between all three. I'm not having many problems with the programming of PICs. I took to PIC assembler like a duck to water. Logical things, on's and off's, algorithms, protocols, these things I can understand. Ever since I've been a boy I can remember (I'm 40 now) being interested in electronics. And it's taken from then to now for me to learn enough to do the simple things I'm doing now. But unfortunately some things I don't understand just yet. Also sometimes it is hard to ask a question on a list the right way to get the right answer. I try to be brief even if it makes me look stupid, since people's time and the answer is more important than how I look. So I do check the books I have, google, etc. before asking in a public forum. I do have this respect for other people's time. Cheers, Lindy --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

> From: Lindy Mayfield[SMTP:.....Lindy.MayfieldKILLspam.....EUR.SAS.COM] > Sent: Wednesday, June 16, 2004 1:03 PM > To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU > Subject: Re: [EE]: Piezo buzzer question, how to connect it > If I understand correctly from what I've so far read, then the answer is > that it only needs one lead, but I just need more juice. > I'll try plugging it into the wall socket, see if I get a 50 Hz buzz. > Thanks to all who answered on this. The element you have is just the transducer, not a complete buzzer. An AC voltage must be applied to it in order for it to make noise. In order to apply this voltage, there must be two wires connected to the element. The first wire is the red one soldered to the piezo material on one side of the brass disk. The second connection is to the brass disk itself. As mentioned in a previous post, the connection to the piezo material is difficult to make, so a wire is supplied to make life easy for you. The second wire, to the disk, can be attached rather easily, so it may be omitted. If so, you must solder the wire yourself without damaging the piezo material in the process. Also realize that the disk vibrates when making sound, so you must make connections to it and mount it such that it is free to move (vibrate) without being excessively damped. Never plug one of these into a wall socket. First, it's dangerous. Second, the voltage is too high. Third, the frequency is most likely too low; typically you need kilohertz signals. John Power -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Thanks Peter. That did help a lot. From this document I have concluded that I need to solder a negative wire on the lower edge on the same side as the red wire. (Instead of on the other side in the middle which is what I tried. It worked ok I guess.) One more question on this please if I may. I found that with the little encased piezo speaker I have that if I feed it a pulse with a 33% duty cycle I get a better sound than if I use 50%. However I read somewhere that you should never use anything other than 50% as anything else may damage the piezo. I find anything about that in this excellent write up below. Has anyone else heard this about the 50%? {Quote hidden}> > A nice article about these kind of buzzers: > www.thedigitalshop.net/techdocs/piezo.pdf > > Manufacturer links catalog with some driver examples and data > for their > piezo's though these have a second wire soldered on the brass > plate: > http://www.murata.com/catalog/p37e18.pdf > http://www.east-mingtao.com/p01_20.htm > > > Hope this helps > > Peter --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I think there are two answers to your question - if the piezo is louder when you drive it with a duty cycle other than 50 % it probably means that the pwm base frequency is not ideal (not the resonance frequency) of the piezo, it would be very coincidential if this happened to be exactly right since ther are not many choices for the base freq. driving it with other than 50% just creates harmonics that are closer to the resonance freq. -the piezo will be damaged (plating corrodes of the piezo) if the dc component of your signal is other than 0 volt. When driving the piezo directly connected from one pin of your pic you will always have a dc component, at 50% duty cycle for a 5 volt pic the dc component would be (50*5 + 50*0 )/100 =2.5 volt the two ways i know to prevent the dc component are (1) driving the piezzo from two different pins of opposite polarity at 50 % duty cycle this would give you a 0 volt dc component (50*10+20*-10)/100=0 volt (2) connecting a capacitor in series with the piezo ( this is ment with the blocking capacitor in the article) this will remove any dc component even without maintaining a 50% duty cycle. Kind regards Peter {Original Message removed}

OOPS made a typo in one calculation ----- Original Message ----- From: "Peter van Hoof" <pvhspam_OUTADELPHIA.NET> To: <@spam@PICLISTKILLspamMITVMA.MIT.EDU> Sent: Thursday, June 17, 2004 6:31 AM Subject: Re: [EE]: Piezo buzzer question, how to connect it > I think there are two answers to your question > > - if the piezo is louder when you drive it with a duty cycle other than 50 % > it probably means that the pwm base frequency is not ideal (not the > resonance frequency) of the piezo, it would be very coincidential if this > happened to be exactly right since ther are not many choices for the base > freq. driving it with other than 50% just creates harmonics that are closer {Quote hidden}> to the resonance freq. > > -the piezo will be damaged (plating corrodes of the piezo) if the dc > component of your signal is other than 0 volt. When driving the piezo > directly connected from one pin of your pic you will always have a dc > component, at 50% duty cycle for a 5 volt pic the dc component would be > (50*5 + 50*0 )/100 =2.5 volt > the two ways i know to prevent the dc component are > (1) driving the piezzo from two different pins of opposite polarity at 50 % > duty cycle this would give you a 0 volt dc component > (50*10+20*-10)/100=0 volt HAS TO BE (50*10+50*-10)/100=0 VOLT > (2) connecting a capacitor in series with the piezo ( this is ment with the {Quote hidden}> blocking capacitor in the article) this will remove any dc component even > without maintaining a 50% duty cycle. > > Kind regards > Peter > > ----- Original Message ----- > From: "Lindy Mayfield" <KILLspamLindy.MayfieldKILLspamEUR.SAS.COM> > To: <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> > Sent: Thursday, June 17, 2004 4:32 AM > Subject: Re: [EE]: Piezo buzzer question, how to connect it > > > Thanks Peter. That did help a lot. From this document I have concluded > that I need to solder a negative wire on the lower edge on the same side as > the red wire. (Instead of on the other side in the middle which is what I > tried. It worked ok I guess.) > > One more question on this please if I may. I found that with the little > encased piezo speaker I have that if I feed it a pulse with a 33% duty cycle {Quote hidden}> I get a better sound than if I use 50%. > > However I read somewhere that you should never use anything other than 50% > as anything else may damage the piezo. I find anything about that in this > excellent write up below. Has anyone else heard this about the 50%? > > > > > > > A nice article about these kind of buzzers: > > www.thedigitalshop.net/techdocs/piezo.pdf > > > > Manufacturer links catalog with some driver examples and data > > for their > > piezo's though these have a second wire soldered on the brass > > plate: > > http://www.murata.com/catalog/p37e18.pdf > > http://www.east-mingtao.com/p01_20.htm > > > > > > Hope this helps > > > > Peter > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.699 / Virus Database: 456 - Release Date: 6/4/2004 > > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> I found that with the little encased piezo speaker I have that > if I feed it a pulse with a 33% duty cycle I get a better sound > than if I use 50% Just a guess - I mentioned that the piezos are quite capacitive. Could it be that the 50% square wave (presumably still directly from the PIC) is being integrated by the piezo ? That is, the spaces between the pulses is being filled in somewhat and so the effective M:S ratio is higher than 50%. At 33% the gaps between are obviously wider. Sounds like a job for your new scope eh ? - find out the quality of the wave -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

in which case, a couple of back to back zeners or a tvs would be an excellent idea! especially if it's going to be used for a while and can be moved or dropped while in use which would shock the piezo nicely, and possibly the micro without protection. a couple of diodes from each line to the power and ground lines might be wise as well, and probably an even better idea than a tvs. i.e. a diode to direct voltages generated to power and ground, hence keeping them from exceeding the supply rails too much. the pic probably has protection diodes to do this, but it's best to add external ones as the internal ones aren't rated for much abuse and may eventually fail. Russell McMahon wrote: --------- {Quote hidden}> An interesting caution. When using these directly connected to a processor > pin NEVER tap them sharply. They act as voltage generators when mechanically > excited and a tap can generate enough energy to destroy a processor ;-(. > Some designs have failed when a piezo which is mounted inside a box has been > subject to a severe shock. The technology is essentially the same as used in > piezo fire lighters. I've never heard of anyone using a fire-lighter as a > speaker, but ... :-) > > RM > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Thanks. Now I cannot find where I read that (I've read so many web pages over the last week). Maybe I dreamed it. (-: You are learning so much so fast that it's hard to fugure out what goes where :-) ! You must be having great fun! :-) You MAY be confusing this with the square wave applied to an LCD which MUST be 50% duty cycle. If not 50% then there is a DC components and you get an elctrolytic cell and the LCD dies rather quickly. The actuial requirement is "no DC" so you can actually have e4g a 40/60 square wave BUT it would need to be assymerical above and below ground so mean DC = 0. Using a series capacitor to fed the voltage ensures this. RM -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

At 09:45 PM 6/17/2004 -0400, you wrote: >The url was in one of my previous posts >www.thedigitalshop.net/techdocs/piezo.pdf >and here is another one with the same kind of story to tell >http://www.scottwestern.com/pdf/page8.pdf >I'm not sure if this is actually true , just some info I have dug up. > >Murata is an important player in piezo and ceramics. > >Peter. I've also read of issues with DC across the ceramic- but note that none of Murata's suggested circuits include such capacitors. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" spamBeGonespeffspamBeGoneinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.