Filter networks have generally been constructed from passive components in the form of resistor, capacitor and inductors. This invention uses active devices in a subnetwork to simulate inductors and combines the subnetworks to provide the desired filter characteristic such as a Butterworth, Tchebychev or pseudo-elliptic filters which are particularly useful in telephone circuitry for handling the audio tones uses in dialling.

The invention concerns a subnetwork of a filter circuit which is useful for detecting the dialing tone used in a telephone system. The arrangement employs active devices such as operational amplifiers in circuit with passive resistive and capactive elements to simulate an inductance S. Although it is known to modify a gyrator circuit to produce a 1/s.sup.2 function it has hitherto been considered that the use of such simulated functions in a ladder filter network would produce an unstable arrang...

The disclosure of the present specification relates to a bridge network suitable for use as a telephone hybrid wherein the bridge network includes at least two bridge networks in cascade, one bridge having arms which include the input and bidirectional ports of the hybrid and the nominal balancing impedance, the other sub-bridge network having arms which include the output port of the hybrid and the output circuit of an amplifier having an output signal characterized by a product of the signal a...

Neural network type information processing devices have been proposed. In these devices, a matrix structure is utilized with impedance at the matrix intersection points. It has been found that excellent versatility in design is achieved by utilizing photoconductors at these intersection points and thus affording the possibility of controlling impedance by, in turn, controlling the level of incident light.

Communication networks, specifically network topologies and apparatus therefor suitable for data communication between computers, tend to be of three main types--those with a star topology (the older sort), those with a bus topology, and those with a ring topology. The ring topology networks have many advantages, but their simpler forms are highly vulnerable to link or repeater failure. The invention proposes another ring network system, which is particularly resilient to repeater and/or link fa...

A serial switched interconnection network comprises several stages of switching units each having a plurality of source ports and destination ports interconnected so that any source port of the first stage can be connected to any destination port of the final stage by operation of switching units in successive stages. Connections are by shared data and control paths each of which paths may comprise a single line or multiple lines and each switching unit when switched to along a path sends a requ...

New controlled and/or sustained drug release amphiphilic compositions based on various amphiphilic networks of the present invention are described. New processes for manufacturing amphiphilic networks are also described. These new processes allow for the production of more diverse amphiphilic networks. The controlled and/or sustained drug release properties of the networks of the present invention show release controlled and sustained release profiles for 20 hours or more and Fickian and non-Fic...

A LAN or other data network includes at least first and second repeater units for receiving data signals and repeating them to other parts of the data network and a transceiver unit for transmitting and receiving data which is connected to the first repeater unit by a primary data link and to the second repeater unit by a secondary data link. The primary data link comprises a primary transmit line for transmitting data from the transceiver unit to the first repeater unit and a primary receive li...

New amphiphilic networks have been synthesized by free-radical copolymerization of hydrophobic methacryloyl capped polyisobutylenes (MA-PIB-MA) with hydrophilic 2-(dimethylamino)ethyl methacrylate (DMAEMA). Two MA-PIB-MAs have been prepared with M.sub.n =4920 and 10,200, and two series of networks were prepared with MA-PIB-MA contents between 48% and 71.5%. Variation of the molecular weight of MA-PIB-MA and its concentration in the network allows for a wide range of mechanical properties and swe...

Techniques are described for making electronic neural networks with variable synapse strengths using the variability of transistor conductance or transconductance with gate bias and utilizing capacitors for the temporary storage of the gate bias used for control.