The first capacitor of 10uF is needed to separate the DC voltage of about 0,6V at the base of the first transistor and the input circuitry.
Without this capacitor, a voltage of 0,6V will flow into your smartphone or tablet 😯
You could also use a 0,1uF capacitor, but the amplified sound will be thinner, due to it’s value. It will then only pass the higher frequencies.
This is a good circuit to test your new oscilloscope 🙂 . I also have a well functioning Rigol scope which I used here to make measurements.
- This reply was modified 4 years, 1 month ago by Michael.
- This reply was modified 4 years, 1 month ago by Michael. Reason: Changed font and size styling for easier reading