Interactive, Open Source Mood Light

Step 3 Add power circuit protection

This part is a simple add-on that uses diodes to protect the wall transformer/batteries from getting fried if you have the batteries installed at the same time you use the DC power jack. You can use any blocking diodes as long as the maximum voltage rating for them is higher than the rating of the wall transformer. The part labeled 'VIN' in the unregulated power strip on the breadboard (which goes to VIN on the arduino). The part labeled 'DCPower' is the DC power jack. For some reason, the program I used to make this schematic was really picky about labels, so that's what it let me name it.

NOTE: If you don't make this circuit, you will NOT be able to keep the batteries in the battery compartment at the same time you have the mood light plugged in to the wall transformer, otherwise it will damage it.