How many Piezo Buzzers can be connected to the Konnected "OUT" pin?

I would like to connect two piezo buzzers to the Konnected "OUT" pin? Does the OUT pin support two piezo buzzers?

@dszigeti did you ever find out about this? I’m trying to do the same.

In my experience, two will work fine. At three they get a little weak sounding.

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Yes, by directly contacting Konnected support.

I concur with Nate that two piezo buzzers work, when wired in parallel. I run two in my house. In terms of the volume, the gauge and length of wire to the buzzer may also be a factor if resistance of the wire is too high.

My research (take with a grain of salt) indicated that the piezo buzzers specifications were 3V at <25mA.

The Out contact on the Alarm Panel Add-on board supplies 3.3V. I have not been able to determine its current output capabilities.

Here is the webpage detailing wiring diagrams for a single piezo.
Wiring diagrams

Ha! And the “Nate” that responded, I have just realized, is likely the Konnected founder! So his advise is likely good.

Konnected Tech Support is also very good, and very fast!

In case Nate reads this post … I would like to ask that the full tech specs of the board’s I/O be published at the site. For example, the OUT terminal is specified at 3V, but we also need to know what its current capabilities are (i.e., mA). Same for the Zones. Using the ESP specifications is complex as we don’t know the circuit.

From the specs that I have available, the maximum output of the OUT terminal or any of the numbered Zones on the Konnected Alarm Panel is 12mA. On the Alarm Panel Pro, the maximum is increased to 40mA. Both at 3.3V.

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Nate, thanks for chiming back in.

Yes, I thought the same. But it is a little worrying if each of the piezo buzzers does take 25mA (probably less though), which implies a total of 50mA draw for two (2). Hence we are overloading the 12mA OUT terminal.

So if we are overloading, then potentially the circuit only survives due to the fact the output is pulsed, and doesn’t burn itself up.

I was hoping the board took the output through a transistor/FET circuit to boost the current capability.

I’ll reiterate that it would be good to have the specifications published.

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wonder if there is a simple amplified piezo driver circuit we can use. I would like to put a piezo in each of my old DSC key pads. I have 4 key pads. I wired up one with a piezo works great but need to add 3 more. Using the pro with the homebridge and it is fantastic. So nice to have my old security system working again!!

Well the answer to your question is not a simple as I would have thought. :slightly_frowning_face:

Note … I haven’t tried this … but …

It seems like what you are going to need is a “direct drive” DC powered piezo. This seems simpler than trying to get an oscillator board … and the oscillator boards seem very expensive. That is, a piezo that doesn’t need an external drive circuit (oscillator).

Here is one option … WEICHUANG 3PCS DC 3-24V 90dB Active Piezo Electronic Buzzer Beep Tone Alarm Ringer Continous Sound (Black) SFM-27-W.

Then I would use an output on the alarm board to to switch a (separate?) DC power supply on/off to these buzzers. The buzzers, I think, would work in parallel, but given the voltage range they have, potentially they might work in series.

Anyway … it is a bit of a project … but not rocket science. :grinning:

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