Matchbox 1932 Mercedes-Benz L5 Spotlight/Generator Truck: Hilden Fire Department, Germany

A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.

An engine-generator is the combination of an electrical generator and an engine (prime mover) mounted together to form a single piece of equipment. This combination is also called an engine-generator set or a gen-set. In many contexts, the engine is taken for granted and the combined unit is simply called a generator. An engine-generator may be a fixed installation, part of a vehicle, or made small enough to be portable.

Many engine-generators use a reciprocating engine, with fuels mentioned above. This can be a steam engine, such as most coal-powered fossil-fuel power plants use. Some engine-generators use a turbine as the engine, such as the industrial gas turbines used in peaking power plants and the microturbines used in some hybrid electric buses.

The generator voltage (volts), frequency (Hz) and power (watts) ratings are selected to suit the load that will be connected. Portable engine-generators may require an external power conditioner to safely operate some types of electronic equipment.

Engine-driven generators fueled on natural gas fuel often form the heart of small-scale (less than 1,000 kW) combined heat and power installations.