1. A device comprising: a battery receptacle comprising a first contact and a second contact configured to electrically couple to a battery in either a first orientation or a second orientation with respect to polarity of the battery; a bridge circuit connected to the first contact and the second contact and having a positive output and a negative output, the bridge circuit comprising: four metal oxide semiconductor field-effect transistors (MOSFETs) Q 1 , Q 2 , Q 3 , and Q 4 , wherein: the Q 1 and the Q 4 comprise N-type MOSFETs each having a source, gate, and drain; the Q 2 and the Q 3 comprise P-type MOSFETs each having a source, gate, and drain; the first contact is connected to the drains of the Q 1 and the Q 3 and the gates of the Q 4 and the Q 2 ; the second contact is connected to the drains of the Q 4 and the Q 2 and the gates of the Q 1 and the Q 3 ; the sources of the Q 1 and the Q 4 are connected to the negative output; and the sources of the Q 2 and the Q 3 are connected to the positive output.