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I have a buzzer with an internal resistance of 16.5 Ohms, which I have used with an Arduino and it worked fine, so I assume it is 5V.

Can I connect a buzzer to the GPIO pins without a transistor, or would it damage the pins?

  • How could I know? I remember using that buzzer with an arduino and it worked fine, so I assume it is 5v. – Euphorbium Aug 8 '12 at 11:12
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The maximum safe current from a GPIO pin is only 16mA

3.3v/16.5Ω would be ~200mA, so No. Definitely not safe

You would need to add a series resistor of 190Ω or more to make it safe to connect and then the voltage across the buzzer will be only 0.26V, so very very quiet

  • V=IR and all that... – Alex Chamberlain Aug 8 '12 at 11:46
  • Could @Euphorbium add a series resisitor? I don't know how buzzers work... – Alex Chamberlain Aug 8 '12 at 11:46
  • @AlexChamberlain, the buzzer would be very very quiet by the time the resistor was big enough – John La Rooy Aug 8 '12 at 11:47

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