Abstract: A “dry” diving snorkel having an elongated body and separate air inlet and exhaust passages defined in the body. The snorkel body is of an arcuate configuration and the lower side of the body upper end faces downwardly during normal use. Air inlet and exhaust ports are defined in the snorkel body upper end lower side in side-by-side relationship, and a diaphragm valve is located within each port biased toward a normally closed condition. The mouthpiece at the body lower end includes a water drain valve, and a strap clamp is molded into the body configuration.

Abstract: There is disclosed a device for use in fruit harvesting, that is, for clipping the stems of citrus fruits. The device is organized for one-hand operation, that is, it can be held in one hand or attached to the wrist of one hand, the device having an operating member, that is, a trigger, to be operated by a finger of the user. The device is powered by a pneumatic cylinder which, through linkage, operates a cutting blade which moves relative to a stationary member. Devices are provided for attaching the tool to a person's wrist and a finger of the user with the trigger member or button positioned for easy manipulation.

Abstract: The present invention relates to a thermally stable crosslinked gelled fluid for use in the treatment of subterranean formations penetrated by a well bore. The fluid composition comprises a pH adjusted aqueous liquid, a gelling agent comprising a selected modified cellulose ether, a crosslinking agent comprising a zirconium IV-containing compound and any additional additives that may be present. The fluid composition is thermally stable under shear at temperatures in excess of about 200.degree. F.

Abstract: An improved process for preparing primary amines from an aliphatic nitrile and hydrogen utilizing a Raney cobalt catalyst which contains from about 2 to 35 weight percent of aluminum on a 100 weight percent total weight basis. Preferably, this catalyst is prepared under low temperature conditions from a cobalt-aluminum alloy. The process can be practiced continuously for extended periods of time at high reaction rates and high conversion yields even when employing concentrated nitrile starting feeds.

Abstract: The invention is an electronic siren comprising in combination circuitry for generating one of a square wave siren and intelligible audio signal and a power output amplifier for audibly reproducing the signal. The amplifier includes transistor circuitry having base, emitter and collector means and a first circuit for coupling the signal-generating circuitry to the base means and one of said emitter and collector means for driving the transistors of the transistor circuitry into saturation in response to the siren signal. The first circuit includes circuitry for applying a dynamic biasing voltage derived from the siren signal to one of the emitter and collector means in phase with the voltage of the siren signal applied to the base means and of a plurality and opposition to the potential drop of the junction of the base means and the other of the emitter and collector means.

Abstract: This invention provides overload protection to power components such as power transistors. A pair of driver transistors is connected in push-pull configuration and is coupled through an auto transformer to a pair of power transistors also connected in push-pull configuration. An impedance-matching transformer couples the pair of power transistors to a load circuit, such as a speaker. A low turn winding is connected in series with the secondary winding of the impedance-matching transformer, and drives a high turn winding in a silicon controlled rectifier trigger circuit which is triggered "on" when an overload condition exists in the low turn winding. Upon conduction of the silicon controlled rectifier, a switching transistor is switched "on" and this, in turn, switches "off" a power disabling transistor which is connected directly to, and in power disabling relation to, the pair of driver transistors.

Abstract: A circuit for switching between two signals of different frequency, such as "wail" and "yelp" of an electronic siren, by switching between different capacitive values in a multivibrator circuit. A monostable switch couples a reference level voltage to an integrated flip-flop circuit. The integrated circuit receives a reference level pulse when the monostable switch is closed and supplies a switching voltage to a transistor circuit. The transistor circuit places capacitances in parallel to change the time constant of the multivibrator circuit and also to change the characteristics of wave-shaping circuitry coupled to the multivibrator circuit. A reference level circuit accepts either of two voltage levels and provides a reference level voltage.

Abstract: The invention is an electronic siren comprising in combination means for generating periodically occurring charging pulses at a selected one of a plurality of predetermined repetition rates, time-constant determining means coupled to the pulse generating means for generating a repeating voltage wave form in response to the charging pulses and means coupled to the time-constant determining means for generating a square wave signal having a frequency proportional to the instantaneous voltage of the voltage wave form. Coupled to the square wave generator is an output circuit which includes a first pair of transistors and first circuit means coupling the transistors to the square wave generator for driving the first pair of transistors individually and alternately into saturation in response to the aforementioned square wave signal.