How to chose a buzzer? - Page 1
Forum section: electronics / beginners

author: Mint.
author_rank: Frequent Contributor
timestamp: July 07, 2012, 06:32:55 am
content: Hello!I am in need of a buzzer and today I've been searching Digikey and Element 14 for one. I finally got to the point that I do not understand much about these buzzers. I am going to use the buzzer on a square wave pulse coming from a 555 timer. Is there some kind of resource I can find that will explain to me about them? Otherwise can somebody please tell me about some of the following characteristics.Piezo vs Magnetic buzzers.Do buzzers care about orientation?Do they get quieter as voltage goes down?How can I decide on a frequency I want?What is the "tone"?- Thanks in advance!

author: Psi
author_rank: Super Contributor
timestamp: July 07, 2012, 06:44:21 am
content: The tone is just the sound they produce. (A tone of frequency x etc..)Buzzers/beepers come in two varieties,Type 1 requires you to supply the waveform at a specific frequency.Type 2 just requires a DC voltage and produces the tone itself.Unlike a speaker a buzzer has a specially tuned sound cavity that will resonate at a specific frequency , 2kHz for example.If you supply a different frequency the buzzer will emit sound but the volume will be very low.(You may be able to get some volume back by using a harmonic of its intended frequency, but you generally just buy a buzzer for the frequency you want)If you care how the buzzer sounds you might want to use some audio software to produce a few available tones and check which sounds the best for your application.When you drive a type 1 buzzer from a microcontroller's hardware timer make sure you use the timer output pin. If you try to set/clear the buzzer in software, even in an interrupt, it can sound "dirty". This happens because other interrupts happen and delay the buzzer interrupt. So the tone becomes unstable and you lose the pure sound.Type 2 is much easier to work with but often costs more.The various types (pesio, magnetic etc.) don't really effect how you drive them. The data sheet will specify a rated voltage and frequency.If you want less volume use less voltage.The orientation doesn't matter.

author: Rerouter
author_rank: Super Contributor
timestamp: July 07, 2012, 06:45:22 am
content: for your tone, it depends on what you are trying to do, for general attention grabbing, 440Hz is pretty commonly used in vehicles,

author: Mint.
author_rank: Frequent Contributor
timestamp: July 07, 2012, 06:48:51 am
content: @ Psi:Looks like I am going to be using a type 2 buzzer. Thanks for clearing that up for me.@ RerouterWell I am going to be using a buzzer in a little notification system that is placed in the same room as the person and then would make the buzzing sound when the 555 timer is activated. I prefer to not have an annoying harsh buzzing sound, just a nice easy notification sound.

author: Psi
author_rank: Super Contributor
timestamp: July 07, 2012, 06:51:37 am
content: I just called them type 1 / type 2 to help in the explanation, that's not an official thing

author: Rerouter
author_rank: Super Contributor
timestamp: July 07, 2012, 06:55:08 am
content: the harshness would come down to your amplitude, when buried in a vehicle dash behind a panel, its noticible, but not harsh, however uncovered is ear bleeding on the small piezio speakers our system use, (driven with 12V DC) this is specifically because the amplitude was planned to be heard through the panelling,

author: Mint.
author_rank: Frequent Contributor
timestamp: July 07, 2012, 07:27:32 am
content: Now that I know a bit more I can go and chose in a bit more detail according to my specifications. However I still don't understand two concepts - operating mode and sound pressure level. Also do buzzers care about orientation e.g. the negative has to go to this lead and the positive has to go to the other, or are they interchangeable?EDIT: I assume for my operating mode I require continuous operation.

author: Psi
author_rank: Super Contributor
timestamp: July 07, 2012, 08:25:17 am
content: Quote from: Mint. on July 07, 2012, 07:27:32 amI'm not sure what you mean by operating mode.sound pressure level is the output volume at it's rated voltage, given in decibels (Higher is louder).Extended exposure over 85 dB and you start to risk hearing loss, 120+ dB and you get instant hearing damage.A civil defense emergency siren designed to warn an entire town is ~138 dB (you don't want to be close to on of those)Quote from: Mint. on July 07, 2012, 07:27:32 amThat's not orientation, orientation means the way it's mounted, eg, on its side or upside down.What you mean is the polarity, yes that will matter for some buzzers.It should be written on the buzzer, often a "+" sign marked into the plastic for through hole buzzers, or a red/black wire for cabled buzzers.The datasheet should tell you all that information.If a buzzer is the type that only requires a DC voltage then it has electronics inside to produce the sound. So this electronics will require the correct polarity. (unless its an AC buzzer and has its own bridge rectifier inside).I'm not sure about polarity on buzzers that require a signal, it may not matter, but it's always best to check the datasheet first.

author: amyk
author_rank: Super Contributor
timestamp: July 07, 2012, 12:21:48 pm
content: Quote from: Mint. on July 07, 2012, 06:48:51 amThen why use a buzzer? They're designed to buzz, not much else. If you want something less harsh use a speaker and one of those melody generator chips (or make your own from a small MCU.)

author: Mint.
author_rank: Frequent Contributor
timestamp: July 07, 2012, 12:52:10 pm
content: Quote from: amyk on July 07, 2012, 12:21:48 pmHonestly I've never used a melody generator chip and the main point of this project is to keep it simple, I don't think I want to make it more complicated than it already is, but thanks for the suggestion.

author: 6502nop
author_rank: Regular Contributor
timestamp: July 07, 2012, 09:33:40 pm
content: Is this for the 555 design I made? If so, then just use:http://www.radioshack.com/product/index.jsp?productId=2062397It's loud enough to get attention, but not too loud to do any hearing damage. It's also got a nice timbre (musical term) for a piezo.The main concerns for anything you throw on pin 3 of a 555 is the voltage and current draw. The output operates about a volt or so off the rails, and you really don't want to pull/push more than 150mA. Some manufacturers claim larger current sinking/sourcing, but if you need more than the standard 150mA, use an output amp (BPT, SCR, FET, etc.). Fortunately, the buzzer linked allows for 6-18V operation at only 10mA, so even large voltage drops will still allow it to work.Note that this buzzer is self-oscillating! This means you don't need to "clock" the 555 output to produce a tone. Just the high output of the 555 is enough to supply it with everything it needs. In fact, you test it by using a 9V battery - no sound = dead piezo.nop

author: Mint.
author_rank: Frequent Contributor
timestamp: July 07, 2012, 11:24:34 pm
content: Quote from: 6502nop on July 07, 2012, 09:33:40 pmYep I am using your circuit, slightly modified however as I went along and tested different components. I can't get the buzzer that you gave me because I am not located in America, but maybe ill find the data sheet and then try to find a similar one to the one you suggested. Also I do not think that I will have any problems with the current, because its just one led and one buzzer at a time.

author: David_AVD
author_rank: Super Contributor
timestamp: July 07, 2012, 11:47:23 pm
content: Altronics sells a decent range:http://www.altronics.com.au/index.asp?area=prod&grp=214This one needs you to drive it with a square wave signal:http://www.altronics.com.au/index.asp?area=item&id=S6090This one just needs a DC voltage applied to make it beep:http://www.altronics.com.au/index.asp?area=item&id=S6104Here's another (cheaper) DC one:http://www.altronics.com.au/index.asp?area=item&id=SX6104

author: Mint.
author_rank: Frequent Contributor
timestamp: July 08, 2012, 12:03:05 am
content: Will this do?http://www.digikey.com.au/product-detail/en/PS1720P02/445-2527-ND/935932My output would be (guesstimating) around 10.5V and I would use a voltage divider to drop it down to the 3v it needs. Would I also need a series resistor to limit the current to the buzzer or not?

author: Mint.
author_rank: Frequent Contributor
timestamp: July 08, 2012, 12:06:21 am
content: Hmmm...Maybe not, Digikey is asking for 34 bucks for shipping!

author: T4P
author_rank: Super Contributor
timestamp: July 08, 2012, 05:16:34 pm
content: Quote from: Psi on July 07, 2012, 08:25:17 amRight...

author: SeanB
author_rank: Super Contributor
timestamp: July 08, 2012, 05:23:24 pm
content: Look for ship fog horns for even more bone shaking goodness.

author: Unknown
author_rank: Unknown
timestamp: July 08, 2012, 05:38:16 pm
content: So, how would you drive this from a 555?

author: 6502nop
author_rank: Regular Contributor
timestamp: July 08, 2012, 11:00:09 pm
content: QuoteThat one should do, but I'm a bit leery about it having no current spec - that lets you know if it's self-oscillating or not. Then, they give a frequency output (2KHz), which indicates it is. Then they list it as "Transducer, Externally Driven", which indicates it's not. Hmmm. Oops! According to the datasheet, the PS series needs an oscillator!That one is no good for our use.You want something more like this:http://www.digikey.com.au/product-detail/en/SCE016SD3CTB/SCE016SD3CTB-ND/1957922but at $20 a pop, you're better off using another 555 to clock a regular piezo at 1-2KHz. Deeeyyyaaaammmm! (and we think RS has high prices - $3.50 is a steal!)And don't worry about current limiting and voltage drops. As long as it is rated within the range you're using (~12V) and current draw (<150mA), you're okay. The buzzer RS sells is rated 6-18V@10mA, by the way. Perfect!If you can't find anything, see if you can find an old Winmodem, which should have the piezo right on the card. Just add a triggered 555 running in astable mode at ~1KHz to drive the piezo, and put that on the output of the first 555. I'll play with the schematic later...QuoteJust use an SLA battery wired through a relay to an automotive air horn. See attached. Be sure to wire the relay "hot" as shown, and use the TIP-120 to switch in the ground (most US cars are wired this way).nop

author: Psi
author_rank: Super Contributor
timestamp: July 09, 2012, 12:18:53 am
content: Quote from: DaveXRT on July 08, 2012, 05:16:34 pmThat is an amazing sound, thanks for posting.

author: Mint.
author_rank: Frequent Contributor
timestamp: July 09, 2012, 12:22:51 am
content: Quote from: David_AVD on July 07, 2012, 11:47:23 pmI got three of those, turns out I need a higher frequency square wave to drive it, more than the 10hz I'm using, but I slightly edited the circuit and the buzzer makes a small clicking noise when it receives a square wave pulse. That is good enough for me!

author: David_AVD
author_rank: Super Contributor
timestamp: July 09, 2012, 01:18:18 am
content: 10Hz is way too low. You'll need to be in the 500Hz - 3000Hz range.

author: G7PSK
author_rank: Super Contributor
timestamp: July 09, 2012, 07:48:57 am
content: There are lots of buzzers available on ebay at a dollar or two AU.http://www.ebay.com.au/sch/i.html?_nkw=electronic+buzzers&_sacat=0&_odkw=buzzers&_osacat=0&_trksid=p3286.c0.m270.l1313For 12 dollars AU you can have three with no postage and they are located in Australia as well, if you want just one or two it very often does not pay to go to RS or digikey.

author: 6502nop
author_rank: Regular Contributor
timestamp: July 10, 2012, 04:23:56 am
content: QuoteThat's just it - DigiKey didn't list any price-points for that item. Buy one, buy a thousand, they're still about $20 a pop! Sheesh!Anyway, as promised, here's the piezo overview for 555 use (and some extra things to put on pin 3)...So, Mint, you'd just add the new driver 555, wiring the receiver 555's pin 3 to pin 4 of the new driver, and wire the piezo up to pin 3 of the driver 555. Another 555 (or swapping with a 556) is still much cheaper than that buzzer.nop

author: Zero999
author_rank: Super Contributor
timestamp: July 11, 2012, 02:23:48 pm
content: I don't know why you're finding this so difficult.Type 12V buzzer into Google, click on shopping and select, a DC one with a current rating of under 200mA. If you want a beep noise go with a piezo with a frequency between 2kHz 4kHz, if you need a more insect-like buzzing noise go with a mechanical buzzer with a frequency between 300Hz to 600Hz. You could also give ebay a go.A car/motorcycle horn would also work but you'll need to make sure the power supply can provide enough current and you'll need additional components: driver transistor, resistor and back-EMF protection diode.It's also very easy to make your own buzzer from four components: a transistor, resistor, capacitor and 8 Ohm speaker.

author: Mint.
author_rank: Frequent Contributor
timestamp: July 11, 2012, 10:19:27 pm
content: Quote from: Mint. on July 09, 2012, 12:22:51 amI've already picked up the buzzers and already using them, thanks for your help everybody!