A swimming pool alarm in the form of an inexpensive compact unit which floats on the water in a swimming pool and which may be anchored to the side of the pool. The unit includes a hollow tubular probe which extends down below the surface of the water in the pool. The probe has an open bottom and a top closed by a flexible metal diaphragm. A piezoelectric ceramic member is attached to the upper surface of the diaphragm, and it serves to detect movements of the diaphragm in response to pressure c...

This invention relates to apparatus for detection and monitoring of improper operation of commutator-brush combinations conveying current to or from the electromagnetic rotary member of a motor or generator, and relates, more particularly, to means for detecting defective brushes in critical motor driven textile units such as yarn storage feeder devices which operate to store yarn temporarily for use by user means such as a loom.

An intrusion detection system includes a transmitter coupled to one end of a coaxial cable, a plurality of antennas spaced along and loosely coupled to the cable, and a receiver circuit coupled to the opposite end of the cable, the antennas being aimed at a protected region. The transmitter transmits microwave energy along the cable. A portion of the energy is transmitted by each antenna into the protected region and is reflected by a moving intruder or target back to one of the antennas. The re...

A fault indicator for indicating the occurrence of a fault current in an electrical conductor includes a rotatable indicator flag having fault-indicating and reset-indicating positions in response to applied magnetic fields. Upon occurrence of a fault current the indicator flag is set to the fault-indicating position by a first magnetic field generated by current flow through the conductor. Upon termination of the fault current the flag indicator is manually reset to the reset-indicating positio...

The invention relates to intruder detection systems of the microwave radiation type in which a number of microwave transmitter/receiver units are placed around an area under surveillance. If a moving intruder is present, the microwave radiation emitted by one or more of the units will undergo a slight change when reflected back to the same unit. Mixing the received radiation within the transmitted radiation will therefore produce a low frequency output which can be detected by a Doppler amplifie...

In a means for detecting the wear of a current interrupting contact (4) there is used a light conductor (12) as a connecting link between the contact (4) and a detector (20) arranged at ground potential. The light conductor is inserted into an aperture (11) provided from the rear side of the contact, the bottom of said aperture being positioned at the level corresponding to a worn out contact. When the wear has grown so great that the light conductor (12) is exposed, the light or heat of the bre...

An alarm housing for a rodent control device such as a spring actuated trap. A frame with opposed side and end members defining a trap opening for receiving the trap, and an electrical switch mounted in the frame so that positioning of the trap in the frame moves the switch to one circuit condition. Tripping of the trap by a rodent produces a lifting action which moves the trap upward out of the frame permitting the electrical switch to move to the opposite circuit condition thereby providing an...

A connecting and sensing device and a method for its use in a system for electrically monitoring physical security, including a magnetically operated switch, such as an encapsulated magnetic reed switch, and a quantity of ferromagnetic material located in a fixed position relative to the magnetically operated switch. The switch is connected electrically to an alarm system control circuit and is physically restrained by a flexible cable or the like. An actuating magnet may be attached either to a...

A fluid level monitor for monitoring the fluid level in a tank comprises a first pair of transducers arranged in a vertically upper horizontal plane and a second pair of transducers arranged in a vertically lower horizontal plane. Pulse generators send electrical pulses to the transmitter transducers which transmit stress waves into the wall of the tank. The stress waves propagating peripherally are detected by the receiver transducers and processors analyze the amplitude of the detected stress ...

A novel electro-mechanical switch device is disclosed which is suitable for use in a factory production line to detect and control the flow of workpieces or articles of manufacture along the line. The switch device includes a pair of switches (101, 102) operative in response to the workpieces passing thereby along the production line, a switch circuit (13) electrically connected to the switches (101, 102), and a moisture detector (15). The pair of switches are so designed that the operation of o...