I picked up some inexpensive passive piezo buzzers for a project and just noticed it says they are rated at 1.5v. I intend to be using them with a selectable arduino pro mini that I am going to switch to 3.3v mode and I wanted to drive it with toneAC2.
Do I need to hook up a resistor in series with it or anything similar due to the voltage difference? If so, how do I calculate the value?
SW
specs from the seller:
HC12085-2P-1
Piezzo Buzzers
Passive Piezo Buzzer
Rated Voltage V 1.5
Operating Voltage V 1-3
Rated Current (max) mA 30
Min. Sound Output at 10cm dB 85
Coil Resistance 16Ω ±4
Resonant Frequency Hz 20-48
Operating Temperature deg C -20~+70
Storage Temperature deg C -30~+80
Weight g 2
That spec does not make sense. If the coil resistance was 16R and the voltage was 1.5 then the current would be 93mA.
However if you want to limit the current to 30mA from 5V then that needs a total resistance of :-
5/0.03 = 166R
Then assuming a 16R resistance from the buzzer that would be 166-16 = 150R which would be a safe value to use.