The nice thing about batteries is that you can add them up to whatever voltage you need. Common electronics voltages are 5V, 9V, 12V, 18V, 24V. You can achieve

The nice thing about batteries is that you can add them up to whatever voltage you need. Common electronics voltages are 5V, 9V, 12V, 18V, 24V. You can achieve all of these with different numbers of rechargeable AA or 9V batteries. However, because of the variety of projects you'll do, to use a wall power source you'll need either a variety of adapters of different voltages, or one of those expensive multi-voltage power adapters, or a proper bench power supply. So, yes, one of those 5V or 9V wall adapters is perfectly fine to use. You simply buy the female portion of the adapter and connect it to your circuit. However, if you do end up exploring multiple projects early on, using batteries will reduce the amount of new expensive gear you need to buy.