What is the correct name for a driven passive buzzer

Hardware
21

I think the ideal thing would be to only provide the students with one type of passive buzzer module. Then you can avoid the need to explain the difference between two different modules entirely. I don't think that understanding the difference between the bare buzzer and an obscure module will be important information for them to take away from the class.

But if you are forced to use both types (e.g., if you already have a significant investment in both types of buzzers), then I guess you are stuck with exposing the students to this complexity.

22

I think this is the way I am going to go. I will mention the different types in the reading material. The real problem is that, as I am writing this, some other teachers are also planning to use it.

It is annoying that Canvas does not have branching in the quiz engine. Then I could start with "Which of these are you using?" and branch accordingly. It is something that has been asked for. Canvas calls it "Adaptive Learning" and it is not the highest priority for them.

But grumping about Canvas is getting way off-topic. You guys (and any ladies) have given me some ideas for how to incorporate this in my class.

23

Both types of buzzer use the same code don't they?
If so the complexity is a hardware detail and loudness.

24

If you deal with output as a function in void loop() that triggers by a value in a variable that other code sets, then you can alternate output functions for alternate hardware, even light a led vs buzz a buzzer functions that work from the same trigger.

That allows keeping a toolbox of output and input functions for different hardware to use in future code instead of weaving IO into process code, IPO modular code style.

25

Do you mean active/passive types or standalone/module types?

26

Unless 1 is pulsed DC and the other steady, yes. In that case there need to be different outputs. But shouldn't a steady DC buzzer work given audio-fequency pulsed signal, just not as loud?

27

It's a nice question. I´ll try this out when I have access to my equipment.

28

For sure see what it does given different tones! It might be weirdly neat!

29

A battery across an active buzzer produces a shrill tone. A battery across a passive buzzer produces a click. The buzzer with "WASH" sticker something are active and have +/- on the body near the legs.

1 Like
30

It's one of those things that usually gets left out of EE classes, that has a lot of complexity once you get into it :frowning:

  1. Mechanical Buzzers - apply power, get noise.
  2. Mechanical speakers, earphones, etc. Apply a signal, get noise. There are a wide variety of sizes, impedences, frequency responses, and power ratings.
  3. Amplified speakers: apply power and a signal, get noise. (a huge variety.)
  4. Piezo active alarms - apply power, get a beep. Usually mounted in a carefully tuned enclosure. Probably "maximum loudness" for a given current happens here (think smoke alarms!)
  5. Piezo passive disks - apply a signal, get a beep. Further divided by whether they have a feedback signal in addition to the driving pins. Piezos typically have a very narrow frequency response, and require higher-voltage drivers to get full power. (heh. I suppose that the historical "crystal earphone" is a sort of piezo device!)

Many of these should use some sort of current limiting or driver if connected directly to a microcontroller pin. 20mA at 5V (typical maximum suggested current for an AVR) is 0.1W...

1 Like
31

Well, here goes the results of the tests. I was lucky to have here both a passive and an active buzzers. I hope this also helps @Hasaf .

image
image800×525 55.4 KB

Check! image

Check! image

I wouldn't use the word "loud". The active buzzer also answers the tone() frequency change, but the sound seems to be a little rattle. Here are the videos (the Forum just allow me to send them in .zip format):

Videos.zip (4,9,MB)

This is the code used to do the test:

int speakerPin = 7;  // Buzzer pin
int i = 0;

void setup() {
  pinMode(speakerPin, OUTPUT);
  Serial.begin(9600);
  delay(100);
}

void loop() {
    for (i == 0; i <= 1000; i+=20) {
    tone(speakerPin, i);
    Serial.print("value = ");
    Serial.println(i);
    delay(200);
  }
  noTone(speakerPin);
}
2 Likes
32

You are missing the point. This is not a software question, except for the possible added functionality I had in the coder above, the ability to turn the buzzer on and off by assigning the Vcc a digital I/O pin.

Instead, it is about what we call the two different types of passive buzzer; the truly passive and the driven passive buzzer. The reason is that they will require different wiring diagrams. Most of these kids are nowhere near the point of telling them, "Here is a passive buzzer, the pins are labelled, get it wired up."

I was looking for the correct names of the two types of passive buzzers. What I gathered is that there isn't a real naming convention.

That is fone, I just didn't want to be teaching them something that was wrong, which would have been the case if the two types of passive buzzer had standard, agreed upon, names that differentiate them. That turns out to not be the case.

As such, the material in the course will say:

There are two Common types of passive buzzers.

Passive Buzzer

This is a Passive Buzzer. You will note that only two of the pins are labelled. The pin labelled - will connect to GND and the pin labelled S, or "Signal," will connect to a PWM pin on your Arduino. The centre pin does not need to be connected to anything. This component is simply a stand-alone passive buzzer attached to a small board with a header, to make it easier to use with our breadboard.

Driven Passive Buzzer
This is a Passive Buzzer Module, which you will sometimes hear me call a driven passive buzzer in an attempt to make it clear which of the two devices I am talking about.

The Passive Buzzer Module differs from the Passive Buzzer in that it is a bit louder, and it needs three wires. The one labelled GND will go to GND. The one labelled I/O will still go to a PWM pin. Here is the difference, the pin labeled Vcc needs to go to 3.5Vdc - 5Vdc.

The students will not encounter a bare passive buzzer, one that is not on a board with pre-soldered headers, in this course. I will mention them while talking, but there is little need to spend much time there.

None of this was about active buzzers. It was about me making sure that I was not violating some pre agreed upon naming convention.

1 Like