I don't recognize the brand of those NiMH cells -- any battery cells from China or cheap cells can do funny things with their output voltage. Even when fully charged. Charged, put it into a torch and the voltage dives down (torch dims quickly). Stuff like that. I woudn't trust any IKEA NiMH cells made in China either.
The DC-DC of the Pico has a minimum input voltage of 1.8V. If my torch can struggle, it won't take much to get the DC-DC to struggle. Depressed voltage from the NiMH batteries may be the cause. Check the voltages with the multimeter or a scope. Or test with a 3V3 supply and compare. You probably need a good power supply for the amplifier -- even the USB-connected output isn't perfect, it crackles a bit at the beginning too.
The DC-DC of the Pico has a minimum input voltage of 1.8V. If my torch can struggle, it won't take much to get the DC-DC to struggle. Depressed voltage from the NiMH batteries may be the cause. Check the voltages with the multimeter or a scope. Or test with a 3V3 supply and compare. You probably need a good power supply for the amplifier -- even the USB-connected output isn't perfect, it crackles a bit at the beginning too.
Statistics: Posted by katak255 — Mon Jan 06, 2025 2:33 am