DROK DC Buck Converter, 6pcs Mini Voltage Regulator DC 4.5-20V 12V 9V Step Down to 5V Reducer Board 3A 10W Fixed Adjustable Volt Output Step-Down Transformer Power Supply Stabilizer Module

It’s also fairly easy to install a gel pouch lithium ion battery into these things, and hook that up to charge from the 9V input. This has saved me an absolute ton of hassle, particularly since the kids love to play with these ones and aren’t great at switching them off. You’ll need something like this:https://a.co/d/01YoIgEu And one of these:https://a.co/d/0bqGOeXv And I found I need an LC filter (with a surprisingly meaty 2200uF capacitor) on the output of the battery module, since the sonicware inrush current was too high for the board itself. There is plenty of empty space inside so you can get a very chunky battery in there.