Abstract: A polarity insensitive solid state switch controlling a shunt load, wherein the switch includes first and second transistors connected in anti-parallel in series with the shunt load; and a longitudinal current sensor controlling the control electrodes of both transistors. The current sensor may be a current sensing resistor in series with a second load. Each transistor may be a bipolar transistor and the current sensing resistor may be connected between the base and emitter of each transistor.

Abstract: An ADSL/POTS filter includes a switchable impedance 220 which is inserted on the low frequency side of filter 2, 3, 5, 6, 7. The impedance is switched by switch 209 which is controlled by a line sensor so that the impedance is switched into the circuit when the telephone 44 goes off-hook.

Abstract: This invention provides an attenuation arrangement for ADSL signals fed from a remote point wherein an attenuator is inserted between a remotely located ADSL LT unit and the line, the attenuation arrangement being for the purpose of reducing the mismatch of downstream power level of the ADSL LT unit and downstream power level of other ADSL signals sharing the same cable bundle but fed from a more distant point.

Abstract: This invention provides an electromagnetic relay formed on a substrate (1), preferably a multi-layer printed circuit board. The magnetic circuit (4, 5, 6a, 6b, 7a, 7b) passes through holes (2, 3) in the substrate, and is formed using printed circuit manufacturing techniques, such as electroplating to manufacture the plated through holes. The armature 7b is formed by depositing the armature material on a temporary layer, which is then removed.

Abstract: A bidirectional equalizer arrangement for cancelling the effect of residual capacitance and/or residual resistive loss in a separation filter having a low-pass filter and a high-pass filter. The equalizer comprises a differential amplifier whose input forms the equalizer's connection terminals, and whose output is coupled, via a transformer, to a positive feedback circuit that includes the transformer's secondary winding, a capacitor and a resistor of predetermined values. When the equalizer is operatively coupled to the low-pass filter, the positive feedback circuit produces a feedback current of opposite polarity and equal magnitude to that produced by the residual capacitance and/or the residual resistive loss, thereby substantially cancelling their effect. The equalizer may be advantageously used with an ADSL/POTS separation filter.

Abstract: A known method of addressing relays in an array is to provide two windings on each relay, wherein one winding is associated with a row drive signal and one winding is associated with a column drive signal, and half of the required activation current is provided by each winding. A known limitation of such addressing arrangements is limited discrimination between selected relays and non-selected relays. The present invention relates to an enhanced addressing system for such arrays of relays.

Abstract: The present invention provides methods for pruning the roots of tree seedlings. The methods of the invention include: (a) a first root pruning step wherein the roots of a majority of members of a population of tree seedlings are laterally pruned; (b) a second root pruning step, occurring after the first root pruning step, wherein the roots of the majority of members of the population of tree seedlings are laterally pruned; wherein: (i) the population of tree seedlings is arranged as at least two adjacent pairs of rows of seedlings; and (ii) the roots of the majority of the seedlings are pruned shorter during the first pruning step than during the second pruning step.

Abstract: A bidirectional bipolar transistor switch for use in customer end telecommunications equipment connected to a telephone line whose line feed polarity can be either positive or negative, for switching low level AC signals. A pair of bipolar transistors are connected in anti-parallel and are operated by a common current sensing resistor in the base/emitter circuit of both transistors. The transistors operate with no DC bias on the collector, and both forward and reverse conductor modes are used.

Abstract: A method of fabricating electro-magnetic relays and arrays of relays using existing and adapted PCB fabrication techniques, in which the activation coils are incorporated into the layers of a multi-layer PCB and the magnetic circuit of the relay is formed partly on the surface of the PCB using, eg, electroplating techniques, and partly in one or more through-holes using plated through holes, the plated through hole plating being extended to form a support for the movable relay contact which is formed on a removable release layer.

Abstract: A known method of addressing relays in an array is to provide two windings on each relay, wherein one winding is associated with a row drive signal and one winding is associated with a column drive signal, and half of the required activation current is provided by each winding. A known limitation of such addressing arrangements is limited discrimination between selected relays and non-selected relays.

Abstract: This invention provides an electromagnetic relay formed on a substrate (1), preferably a multi-layer printed circuit board. The magnetic circuit (4, 5, 6a, 6b, 7a, 7b) passes through holes (2, 3) in the substrate, and is formed using printed circuit manufacturing techniques, such as electroplating to manufacture the plated through holes.

Abstract: The present invention relates to the structure of a magnetic relay for telecommunication network configuration, said relay having a magnetically cantilevered armature, said contact armature having a section with reduced cross section over a part of its length to provide a hinge action. While the invention is suitable for use in miniaturized relays, it can also be used with larger relays.