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Hello everyone!

I am outputting HIGH from arduino to a Buzzer and a LED in paralell. LED will be turned on, but instead of having a uninterrupted sound at Buzzer , I was wondering if I can have it sounding more like a tickle, a short beep.

I can't figure out which components to use but I thought it had to do with some capacitor to switch off some transistor and stop the current to reach the buzzer. Even though it could be the right direction I still lack of knowledge to choose the specific components, and values.

Thanks in advance,

Bontempos~
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Can you use two output pins, one for the led and one for the buzzer ?
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Actually I can't. That's is the problem. Each LED from an output would have its own sound. Let's say.
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Do you have a link to your specific buzzer that we could look over?


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Sure! I haven't yet chosen any specific, but I would try this for a start.
http://www.marutsu.co.jp/shohin_64927/

It is being driven at 12V together with LEDs.
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Well an arduino output pin can't switch +12vdc directly, you will have to use a switching transistor. As far as having a brief pulse of the buzzer you might try wiring a  large electrolytic capacitor in series with the buzzer. Start with maybe 470 ufd and adjust higher or lower to your requirement.

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Thank you for your reply!

I am using a transistor switch to turn on the led at 12v. From the transistor output to the led, I understand you mean I could wire the buzzer (in parallel with led) and a capacitor in series with the buzzer, in this order: transistor output -> buzzer -> capacitor.

I don't really understand all the properties of the capacitor, I just want to visualize it this way.
During HIGH, Buzzer will produce sound as its volume decreases while capacitor charges. When capacitor is charged buzzer is mute.
If I set LOW in this scenario, wouldn't buzzer produce a new sound with the charge of capacitor?
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Actually I can't. That's is the problem. Each LED from an output would have its own sound. Let's say.
Yes, you can... with an Arduino Mega 2560.
http://arduino.cc/en/Main/arduinoBoardMega2560

Or use a single piezo element and the tone library to make different sounds.
http://arduino.cc/en/reference/tone

When you can control the buzzer and led in software seperately, you can do with them whatever you want.
« Last Edit: July 10, 2014, 07:07:37 am by Peter_n » Logged

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Why do you need a buzzer for each LED? Isn't one buzzer enough?

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Actually I can't. That's is the problem. Each LED from an output would have its own sound. Let's say.
Yes, you can... with an Arduino Mega 2560.
http://arduino.cc/en/Main/arduinoBoardMega2560


Why do you need a buzzer for each LED? Isn't one buzzer enough?



I am sorry that I lacked enough information about my project. Actually the point of the question (and mostly because I am curious about the electronic components usage) was to get to know if that would be possible to use the buzzer, (or piezo) in a way it would produce just a beep even if on a constant HIGH output.

I am using an arduino MEGA, and unfortunately it already have all outputs compromised with one led each. In this project each led will be displaced on a 3D space, so the sound and light would have the exactly same source  - for the user experience.

I have already used the tone() in a previous experience and of course if I had extra outputs life would be easier for this project smiley-wink
That's why I set that question regarding the use of maybe a capacitor and a transistor. The idea of using the transistor would be that it would cut the sound of the buzzer/piezo instead of decreasing its volume - but I guess that the right capacitor would work this idea out by itself.

I don't have the capacitors here to make a test but I was just wondering if, in previous scenario, the capacitor charge would produce another beep (any sound) when I set LOW to the circuit, after setting it HIGH.

Thanks!!
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I am using an arduino MEGA, and unfortunately it already have all outputs compromised with one led each. In this project each led will be displaced on a 3D space, so the sound and light would have the exactly same source  - for the user experience.

I see....

I have already used the tone() in a previous experience and of course if I had extra outputs life would be easier for this project smiley-wink
That's why I set that question regarding the use of maybe a capacitor and a transistor. The idea of using the transistor would be that it would cut the sound of the buzzer/piezo instead of decreasing its volume - but I guess that the right capacitor would work this idea out by itself.

It may be possible to hack something together where a capacitor charges up over time and cuts off the sound when it reaches a certain voltage.

But...imagine all the time it will take to build 56 little things (or however many there are), each with a capacitor/transistor/resistors/555 timer/whatever.

Now imagine that a second Arduino Mega costs about $20. Is it really worth building all that stuff?

PS: You could also do it with a bunch of shift registers to expand the I/O pins, a network of Pro Minis instead of the Mega...there's all sorts of ways to do it.

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fungus is right, use another Arduino Mega board or an I/O expander (like shift registers or I2C I/O expanders).
If you plan to make a circuit for every 56 items, why not go all the way and have 56 Arduino boards ? like the Trinket.
http://www.adafruit.com/products/1501

There are logic-595-type shift registers that are capable to drive leds directly.
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Thank you for your advices!

Indeed, I am already suffering a lot with all the soldering I have to do by far, it would be really a problem to add something more. I was just wondering that it was just something I could manage with a capacitor, that would be something I could do.

Of course using another arduino would be best solution so I could use simply buzzers on each ouput. I have never tried to use more than one at same time nor tried to sync them. Both would be compiled with Standard Firmata, receiving commands by serial. Probably same information, but the code would change on the second arduino to implement the Tone function, I guess.
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I have never tried to use more than one at same time nor tried to sync them.

Megas have lots of serial ports. It shouldn't be difficult to make them talk.
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