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Help with circuit to use either batteries OR a DC "wall wart" power pack. Answered

I would like help with the type of circuit used in devices that can use either batteries, or a "wall wart"(AC to DC), or possibly even an AC cord if I decide to go that route (like a battery/ AC powered radio). I have a basic knowledge of electronics, but need help with this one. Is it very complicated? I'm not sure of specifics at this point, such as how many and what types of batteries (AA, AAA, 9V) what voltage, etc., just need to know how to build a circuit for this purpose. My project will use a single bright L.E.D, or possibly more, (maybe 3 watts each) and I would like to have the ability to plug it up if someone either doesn't have the batteries, or would just prefer to plug it up at all times. How does the device switch between battery and plug in? Thanks for anyone's time and help! I really do appreciate it.


I too am looking for a kit or parts that I can put together to create a plug in / battery charge / battery use system as a modification to an old boom box stereo. The system should basically work as an iPhone does with the ability to easily plug in and unplug while using and charging the battery simultaneously. I know it can be done. I'm just looking for a web shop or resource where I can investigate and / or buy the parts to put together.


4 years ago

Here is a battery whatever voltage you want to run on the right side through 1 diode.

On the left side you select a wall wart with a bit more voltage then the battery.

When plugged in the battery can be re-charged and the top diode feeds the right side load.