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Adding headphone jack to piezo buzzer

lmrubin

Oct 9, 2020
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Oct 9, 2020
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Sorry - this is probably a basic question for people who know what they're doing...
I built a metal detector (pcb with components) which works. It has a piezo buzzer only. I'd like to be able to add a headphone jack which only works when headphones are plugged in - so if there are no headphones plugged in, the buzzer still works. The PCB has 2 pads for the buzzer. I have a stereo 3.5mm jack. Can this be done without getting overly complicated? Any tips or assistance is greatly appreciated.
 

Harald Kapp

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Nov 17, 2011
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Assuming the buzzer is connected from a tone generator's output to ground (0 V):
You need a headphone jack with integrated switch. See the example here, figure 2:
pin 1 = ground (0 V)
pin 2 = signal output from tone generator
pin 0 = signal to buzzer

Show us a schematic diagram of your circuit so we can verify this will work.
Also note that there's a possible catch or two:
  1. The tone generator may not have sufficient power to drive the headphones.
  2. The buzzer may be of the active type which doesn't require a tone generator at all but beeps when connected to power.
In both cases headphones will not work.
 

strawbone

Aug 7, 2023
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Aug 7, 2023
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Hi, I would like to create a similar circuit where i have a power supply powered by batteries, and a piezo buzzer, I want to hear the buzzer through the headphones and also at the same time the buzzer acts as a speaker.
Context: I want to listen to the sound of buzzing from the buzzer and at the same time the people around me can hear the buzzer buzzing
I'm not really well versed in this area, would like some expert help. TQ
 

AnalogKid

Jun 10, 2015
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As above, it depends. There are two basic types of piezo beepers. One takes DC power and has an internal oscillator that drives the piezo element. Adding an earphone jack to this type will not work, because the audio signal is internal to the beeper device.

The other is a bare piezo element, and it is driven by an oscillating signal from wherever. In this case you have a chance, depending on the nature of the driving signal. Some small piezo elements can handle a 30 V signal, which would be bad for both your ear buds and your hearing.

Also, it is not polite to impose your question on someone else's thread, particularly when the thread died out almost 3 years ago. Better to start your own thread, and reference this one with a link for context.

ak
 
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