Improved methods of battery charge and/or discharge control make use of an electrical device which is connected in series with the cell or cells of the battery and which is preferably a permanent part of the battery, so that when the battery terminals are connected in order to charge or discharge the battery, the device provides an automatic guard against excessive battery temperatures and/or current discharges. The device comprises a PTC element which is preferably composed of a conductive poly...

A switching circuit connected between a power supply and a load such as a trapatt diode amplifier. The amplifying element is protected from destruction, in the event that the amplifier should break into oscillation. Two serially connected monostable multivibrators control the conduction state of a transistor whose collectoremitter conduction path is in series with the amplifier, thereby limiting the peak, steady-state and average power that the power supply can deliver.

A cathodic protection system for a metal substrate has an anode which is normally electrically insulated from the substrate but which is disposed very close to the substrate. Cathodic protection only becomes effective when the electrical insulation breaks down and the metal substrate would otherwise be subject to corrosion. The system comprises an electrically insulating coating on the metal substrate and an electrically conducting coating applied over the insulating coating, a D.C. voltage bein...

Protection apparatus is disclosed for use with a hair curling iron having a curling clamp and a heating element. In the preferred embodiment, the protection apparatus includes a guard and a comb retainer. The guard includes a trough member for receiving the heating element and curling clamp of the curling iron to aid in preventing the heating element of the curling iron from accidentally contacting the head of the person desiring their hair curled and a U-shaped slot for removably receiving the ...

The amplitude is detected of both the input and output signals of the circuit (such as an audio amplifier) it is desired to protect. When, for example, a short circuit occurs across the load being driven, there is a sudden change in the ratio of these amplitudes and in response to this change, the signal to the output driver stage of the circuit is shunted to ground.

A method for protecting ground surfaces from spilled petroleum products, i.e. in bund areas, which comprises covering the surface with a layer of fibre reinforced unsaturated polyester resin applied on top of a membrane which is impervious to the resin and sufficiently flexible to accommodate the ground contours.

The disclosure relates to a motor protection circuit utilizing PTC sensors and all solid state circuitry to provide protection to a motor circuit and the like. The protection circuit is capable of providing protection for a plurality of devices simultaneously. The sensor circuits can be connected either serially or in parallel and provide equivalent results. This invention relates to a protection circuit for use with motors and the like and more specifically to an all solid state protection circ...

An automatic electrically operated protective system protects a welder from harmful light rays and sputtering emanating from the weld zone. An electric circuit controls a light shield means to assume either an open or closed condition. The electric circuit is responsive to the absolute value of the voltage between a welding electrode and a workpiece. A light shield opening signal is produced when this value is smaller than the electrode open circuit voltage but greater than the maximum electrode...

A protection chamber for temperature-sensitive or moisture-sensitive materials, comprises heat insulated wall elements which are joined in a butt joint. A semielastic sealing compound is disposed in the joint; and an additional sealing compound of a material of greater elasticity is disposed at but outside the joint. A cover profile overlies the additional sealing material and the adjacent edges of the wall elements and is arcuate in the zone of the additional sealing compound but has relatively...

A protection circuit for communication equipment connected to a two conductor communication line includes a bridge rectifier having alternating current terminals connected to the conductors and to ground. The direct current terminals of the rectifier are connected to a device responsive to a range of predetermined voltage and current conditions in the conductors for reflecting foreign electrical energy.