For opening and closing garage doors it is usual to provide a mechanical door opener of some type which is powered by an electric motor. A receiving device is installed in the garage and a transmitter located somewhere in the driver's compartment of the automobile. The transmitting device may, for convenience, be mounted on the steering column, on the sun visor, or may be kept loose in the glove compartment of the car or may be kept at any other convenient location. To operate such a system, the driver may press a button on the transmitting device causing the transmitter to emit a radio signal of some predetermined frequency. The receiver in the garage, being tuned to this frequency, is activated, and, through suitable relays, activates the motor to open the garage door.
The transmitter, whether mounted on the steering column of the car or carried loose in the car, is powered by a battery for this purpose which is contained with the transmitter in a casing. These batteries have a limited life and have to be replaced periodically.
It is customary that passenger automobiles be provided with electric lighters for cigars or cigarettes and such a lighter is placed in the drivers compartment of the automobile, usually being mounted on the dashboard of the car. These devices include a socket the walls of which are electrically connected to the negative side of the automobile battery, and a contact within the socket which is electrically connected with the positive side of the battery. In these devices a plug is arranged to be pushed into the socket and into engagement with the contact and so energize a heating element which the driver may remove and use for the purpose of lighting a cigarette.
However, many drivers do not smoke, or choose to light their cigars or cigarettes by other means, and electric lighters in their cars are frequently unused.