Connected in circuit between a regular two-cell battery and the light bulb in an otherwise ordinary flashlight is an auxiliary voltage source, such as a third battery cell of relatively small size. The bulb is normally powered directly from the regular two-cell battery. However, if a boost in light output...http://www.google.ca/patents/US5214353?utm_source=gb-gplus-sharePatent US5214353 - Flashlight with boost feature
