How to tell if a buzzer is passive or active?

Question

I see a lot of buzzers (like this one) that are sold online and don't advertise whether they are active (a DC power signal produces noise) or passive (to make noise they require both the DC power signal and an additional signal).

How can I tell if a buzzer is passive or active if its not immediately advertised by the distributor/website?

score 6 · Accepted Answer · answered Sep 08 '17 at 01:07

6

Passive Piezo Buzzers run on AC only, no DC required. They're also often not called 'Buzzers', but rather 'Transducers', 'Elements' or similar.

Active Piezo Buzzers run on DC, and usually the frequency they produce is specified.

The one you link to is, without a doubt, an active buzzer, whereas this one is a passive transducer.

answered Sep 08 '17 at 01:07

brhans

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@smeeb Some additional assurance that a piezo is passive is seeing a frequency range like 1500 - 3000 Hz. An active buzzer likely oscillates and emits at one specific frequency. – glen_geek Sep 08 '17 at 01:23

score 3 · Answer 2 · answered Feb 25 '19 at 23:16

The two buzzer seems the same but:

if you apply a DC voltage to them and it buzzes, it is an active.
the height of the two is slightly different, the active buzzer has a height of 9mm, while the passive has height of 8mm.
pins side, you can see a green circuit board in passive buzzer. No circuit board and closed with a black is an active buzzer.
Using an ohmmeter, if you find the resistance between buzzer pins is about 16ohm (or 8ohm), the buzzer is passive.
An active buzzer has a built-in oscillating source so it will oscillate at one specific frequency. So the seller will mention if it runs at a specific frequency --> active or range of frequencies 2Khz-5Khz -->Passive

How to tell if a buzzer is passive or active?

2 Answers2