GB1429009A - Selectable fixed impedance device - Google Patents

Abstract

1429009 Resistors; inductors; printed circuits BOURNS Inc 3 April 1973 [25 May 1972] 15857/73 Headings H1S H1R and HIT An impedance device 10 has a substrate 12 upon which is provided a network 14 comprising resistive, inductive, capacitive or semi-conductive elements or any combination thereof and which has end and intermediate terminals 16E, 161 so that the impedance of the network can be fixed at a selected value by appropriate connections of the intermediate terminals 16I to one or more conductive members 20, e.g. by solder, conductive epoxy or a conductive insert. A resistive device, Figs. 1, 3, has a substrate 12 of ceramic, glass or plastics material, or a metal coated with one of these materials. Applied on the substrate are metallic terminal layers 16I, 16E and a resistive network 14, e.g. of a layer of cermet material containing noble metal(s) or oxides thereof. Metallic films, carbon, or wires can alternatively be used for the network 14. The network is sealed by an insulating coating of for example plastics or glass. Between the terminals 16 extend parts of an insulating member 22 in which are embedded the conductive members 20. Diagrams illustrating ways in which sections of the resistance network 14 are connected are depicted in Figs. 4 and 5 (not shown). In the modification of Fig. 6 (not shown) a conductive member (20<SP>1</SP>) is printed on or embedded in the surface of the substrate (12<SP>1</SP>) and is connected to selected terminals 16 by solder or conductive epoxy located in grooves (26) in the substrate. The embodiment of Fig. 8 (not shown) provides a Kelvin-Varley voltage divider circuit. An inductive device, Fig. 11, similar to that shown in Fig. 1, has a network which comprises series-connected flat windings 46W around a core 46C of, for example, ferrite material. Windings 46W may be of the same material as terminals 16.