Audio question

[Bobman]

I notice that the audio output can be speaker or headphones but can the circuit on page 99 of ITMD be used as I wish to have the speaker disconnected by the headphones? I can see subtle differences of resistor value and placement between the two circuits and wonder if I would be upsetting the operation of the mpsa13 by using the ITMD method?

[Qiaozhi]

I notice that the audio output can be speaker or headphones but can the circuit on page 99 of ITMD be used as I wish to have the speaker disconnected by the headphones? I can see subtle differences of resistor value and placement between the two circuits and wonder if I would be upsetting the operation of the mpsa13 by using the ITMD method?

If you want to have an internal speaker, but have it disconnected when you plug in the headphones, you need to connect a headphone jack socket to PL5. It needs to be wired so that the speaker is operational with nothing plugged in (default mode of operation), but when the headphones are plugged in, the speaker cuts out.
If you examine the jack socket, and the way the connections open and close when a jack plug is inserted, you should be able to figure it out.
The resistors in Fig. 9-16 on page 99 are not required for the Nano PI circuit. You don't need to change the audio circuit in any way. Just connect the jack socket to PL5.