Abstract: An emergency vehicle audible warning system having a control circuit with a means for switching said control circuit to activate a tone generator for creating a yelp tone or a wail tone. A siren amplifier interfaces a siren speaker and the yelp and wail tone generators. A series of switches are also provided in operative connection with the horn ring of an automobile or a foot switch, so that the yelp or wail tone can be effectuated thereby, upon the demand of the driver of the emergency vehicle. The change from the yelp or wail tone can be provided by either a change in capacitance, or a change in the resistance within the tone generating circuit. In addition thereto, an extended yelp tone is provided by means of a timing circuit or increased time delay function to maintain a yelp tone or another desired tone for an extended period of time after either the horn switch, foot switch, or other appropriate switch has been momentarily activated and then released.

Abstract: A compartmentalized full face mask having a flexible sealing flange around the periphery thereof for sealing the body of the mask against a diver's face. The body of the mask has an upper facially oriented opening for receipt of a viewing lens, and a lower opening for receipt of an accessory plate. The lens and accessory plate are secured in the face mask by a band which circumscribes the outer periphery of the body of the face mask for tightly holding the viewing lens and accessory plate in a groove in the body of the mask.The lens and accessory plate partially define an upper and lower chamber with a nose portion and a sealing flange dividing them. The sealing flange provides a lower chamber which can be utilized with accessories of various types in a manner not possible in the prior art. The lower chamber also serves to enhance the underwater sound transmission capabilities of the mask.

Abstract: The following specification discloses a foot fin for propelling one through the water, having a blade surface that can be oriented within the same axis as the leg of a user. The foot fin enables one to propel oneself through the water and maintain a similar axial orientation of the driving portion of the fin, to the user's leg. In order to provide for walking while the fin is not being used in the water, a hinge point is inserted within the fin to allow it to be placed within the same general plane as the sole of a user's foot.

Abstract: The following specification discloses a current noise and dielectric absorption kickback compensation circuit for a force line and a sense line that are to be initially compensated with regard to unwanted currents therein. The lines are placed in a shielded cable and mutually receive the same external noise signals. The unwanted currents are incurred in the force line and the sense line which is connected to a device under test, such as an integrated circuit, that is to have a particular voltage forced thereon and a determination made or sensed as to the current drain thereof. The force and sense lines can be initially connected to a tester which is controlled by a computer. The lines lead to the device under test through various lines interconnected by relay matrices which provide a number of different functions for testing the device under test, such as timed events, voltages, and external active or passive elements used cooperatively with the device under test and the other pins thereof.