Hi all, I just got my DSO Nano v 1.3 two days ago 
. It took me a while to figure out how to disassemble it (hint use a razor or Xacto to gently peel off the front label, remove 6 small screws).
I already knew that the Battery Charger-Power Supply circuit was an issue. Yes there is a protection circuit built-in the battery, but charging with a Schottky diode and a 1 Ohm resistor will guaranty short battery life. I have designed a fix which actually cost less than the original circuit. This will require a change in the PCB. (I have tried to load this to here, but every format I try is rejected. it is available as a MS Word. doc, and PDF)
I have a question: The test waveform showing quite a bit of peaking. Why? (Capacitors C0, C5, C3A, C4A, C6A are not installed)
I have also been thinking about the input amplifier IC, TL082. This is not the best (it is really happier with more voltage on the +/- power pins, it is noisy, and it has limited bandwidth) for this use.
A differential amplifier would be much better. This would eliminate some noise and allow using shielded twisted pair wire (like that use in tie clip microphones) which would eliminate more noise. This would require that the tip and ring of the input connector be brought to the main board, which should be easy. I have some ICs in mind, one of which has programmable (serial) gain from 0 to >-50 dB.
A couple of capability questions: can you use smaller parts (i.e. QFN)? Many of the newer ICs are only available in smaller package.
Is SeeedStudio making the small PCB with the pushbuttons? It would be better to put the input amplifier there, where it can be easily shielded. Moving the amplifier here would also allow different versions (i.e. differential, AC-DC, single ended, multiplexed 2 channels, etc)
I saw a comment about storing different set-ups. This should be to the memory card (perhaps 8 memories). It would require choosing “Save Image” or “Save Set Up” when saving.