Abstract: Apparatus for measuring the ambient light intensity of a monitored area during consecutive time intervals whereby an indication is given whenever the difference in any one of these measurements and the immediately preceeding measurement exceeds a predetermined value. The output signal of a suitable light sensing device such as a photocell is converted to a pulse train having a frequency proportional to the ambient light level and supplied to one input of an AND gate. The other input of the AND gate is connected to receive consecutive, equal duration, timing signals generated by a one shot timer circuit controlled by a microprocessor. The output of the AND gate supplies a finite number of pulses to a pulse counter, also controlled by the microprocessor.

Abstract: The disclosure concerns an apparatus for generating gas by the reaction of water reactive gas producing fuel with water vapor. A chamber houses the metal hydride fuel and a water vapor is introduced into the fuel chamber through a pair of spaced porous hydrophobic membranes. Reaction of the water vapor with the fuel produces a gas such as hydrogen (if calcium hydride fuel is used) or oxygen for use in a fuel cell. A "dead space" is positioned between the porous hydrophobic membranes which provides a safety feature that is unique in its use. If, during operation, an excessive sudden demand is made for the generated gas, i.e. hydrogen, and in turn for water vapor, with this invention, unvaporized water which might be pulled through the outer membrane or membranes will then pass through the hydrogen outlet rather than accidently directly contacting the fuel.