We need to connect a small speaker- a headphone one, to an Microchip Pic. I don't know whats the resistance of such speaker(it's very small) but I guess it's 8-ohm. (We are only using one headphone speaker, not both.)
I know the Pic can output 20mA in a port, so with
5V output and
20mA I have about
0.1W to use, which is good enough (Does not have to be audible to humans, this will be audio-coupled to a microphone).
Not knowing the speaker's impedance or current requirements, I was wondering if connecting them with a 300Ω resistor, directly to the mcu (with a dc blocking component), would produce something, or am I missing something?
Please don't advice an op-amp. I know about them, but am trying to avoid that, because I need a small signal and very small power draw.