Core Electronics Forum

Connecting a speaker and ItsyBitsy

I am going to be using an Adafruit ItsyBitsy M4 Express (ADA3800) with a 8ohm 0.25W speaker what components and how do I connect them to ensure the .wav files I play through the DAC do not damage the speaker or ItsyBitsy

Hey Christopher,

Given that the ItsyBitsy provides an output of 3.3V according to ohms law of V=IR and P=IV, P=IIR. Therefore a 0.25w speaker would draw around 177ma (sqrt of 0.25/8). As the ItsyBitsy is limited to a safe 20ma output on the logic pins it’s a good idea to add a circuit that isolates the logic from the board to the power source for the speaker. An optical isolator or optoisolator could be used to achieve that effect.

From Bryce