DIY: I want to power a small device with solar power.?

Not worth the effort. If you don't want to spend much then you can buy cheap battery portables, or even cheaper USED battery portables from Ebay or other online sites. If your speakers work off a mains adapter then you just need a battery box that holds the right no.

Of batteries. The mains adapter will have a label that tells you the voltage, and standard batteries are rated at 1.5 volts so your battery box can be 3/4.5/6/9/12 volts because you can get boxes to hold 2/3/4/6/8 batteries. If you use your speakers a lot then throwaway batteries may not be a cheap answer.

Most line-powered items need more energy than a battery of reasonable size can provide. Consult with an experienced local electronic hobbyist for hands-on help.

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