GB2189959A - Attenuator apparatus - Google Patents

Abstract

Attenuator apparatus (2) comprises first and second resistor networks which are provided on at least one substrate, and a switching matrix (14) of attenuator pins (16), the attenuator pins (16) being for receiving connector means (18), the connector means (18) being connectible between different attenuator pins (16) to place appropriate parts of the first and/or second resistor networks in circuit to afford different desired attenuation values, the first and the second resistor networks, the substrate and the switching matrix (14) of attenuator pins (16) all being mounted on a printed circuit board (12) and all being housed in a housing (22), and the housing having inwardly projecting abutment means (28) against which the printed circuit board (12) rests in order to position the printed circuit board in the housing. <IMAGE>

Description

SPECIFICATION Attenuator apparatus This invention relates to attenuator apparatus.

In our United Kingdom patent specification No.

2172163Awe have described and claimed attenuator apparatus comprising first and second resistor networks which are provided on at least one substrate, and a switching matrix of attenuator pins, the attenuator pins being for receiving connector means, and the connector means being connectible between different attenuator pins to place appropriate parts of the first and/or resistor networks in circuit to afford different desired attenuation values.

The attenuator apparatus described in our said patent specification may conveniently be produced for sale if it is provided with a special type of housing.

Accordingly, the present invention provides attenuator apparatus comprising first and second resistor networks which are provided on at least one substrate, and a switching matrix of attenuator pins, the attenuator pins being for receiving connector means, the connector means being connectible between different attenuator pins to place appropriate parts of the first and/or second resistor networks in circuit to afford different desired attenuation values, the first and the second resistor networks, the substrate and the switching matrix of the attenuator pins all being mounted on a printed circuit board and all being housed in a housing, and the housing having inwardly projecting abutment means against which the printed circuit board rests in order to position the printed circuit board in the housing.

The abutment means may be a plurality of knobs.

Preferably, four knobs are employed.

The housing may be closed by a lid.

Advantageously, the open end of the housing and the lid have complementary inclined mating surfaces for enabling the lid to be a flush fit on the housing.

Preferably, the inside of the housing is provided with a plastics foam material. The plastics foam material is arranged to be such that it is compressed by the first and the second resistor networks, the substrate, the switching matrix and the printed circuit board, the compressed plastics foam material then providing a relatively solid shock-absorbent base.

Preferably, the plastics foam material is polyurethane foam material. Other plastics foam materials may however be employed.

Advantageously, the complementary inclined mating surfaces of the housing and the lid are inclined at an angle of 45 .

The housing and/or the box may be made of a plastics material such for example as nylon. Other materials may of course be employed.

The first and the second resistor networks, the substrate and the switching matrix of attenuator pins may all be as described in our said patent specification No. 2172163A.The disclosure in patent specification No. 21721 63A is incorporated herein by reference.

As indicated in patent specification No. 2172163A, first and the second resistor networks may be provided on first and second substrates respectiveiy. Alternatively, the first and the second resistor networks may be provided on one dual in line substrate.

The printed circuit board may act as a base mounting printed circuit board. The printed circuit board may be regarded as a mother printed circuit board.

The attenuator apparatus of the present invention may be sold with or without the connector means.

The connector means may be two section electrical shortening links, each link having a pair of end caps for fitting over a pair of the attenuator pins, and the links being usabie in pairs.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows first attenuator apparatus; Figure 2 is a top plan view of the housing shown in Figure 1; Figure 3 is a side view of the housing shown in Figure 2; Figures 4, 5 and 6 are respectively underneath, side and a part sectional view of an alternative housing; Figures 7 and 8 are underneath and end views of a lid; and Figure 9 is an enlarged detail of part of the lid as shown in Figure 8.

Referring to Figures 1 to 3, there is shown attenuator apparatus 2 comprising first and second thick film resistor networks (not shown) which are provided on a substrate 4. The substrate 4 is a ceramic substrate and it is connected to a first printed circuit board 6 by means of mounting pins 8.

The first printed circuit board 6 is a plated through hole printed circuit board. The mounting pins 8 are preferably 0.025" mini-wrap pins.

The substrate 4 is provided with mounting pins 10 and the mounting pins 10 enable the substrate 4 to be attached to a second printed circuit board 12. The mounting pins 10 may be solder pins that are soldered in position on the second printed circuit board 12. The second printed circuit board 12 may be regarded as a mother printed circuit board, and the first printed circuit board 6 may be regarded as a daughter printed circuit board.

The first printed circuit board 6 is provided with a switching matrix 14 of attenuator pins 16. The attenuator pins 16 are shown in more detail in our above mentioned patent application. The attenuator pins are connected by connector means in the form of pairs of electrical shortening links 18. As shown in Figure 1, each link 18 has a pair of end caps 20 for fitting over a pair of the attenuator pins 16. The links 18 are used in pairs.

The various parts shown in Figure 1 which are attached to the printed circuit board 12 are provided in a housing 22 and the attenuator pins 16 extend through slits 24 in the top 26 of the housing 22.

The printed circuit board 12 is located and rests on inwardly projecting abutment means in the form of four knobs 28 which extend inwardly in the housing as shown in Figures 1 and 3. The housing 22 is provided with polyurethane foam material 30 which becomes compressed as the printed circuit board 12 is pushed on to the knobs 28. The polyurethane foam material forms a good shock absorbent material.

The open end of the housing 22 is closed by a lid 32. The lid 32 has 45" inclined edges 34. These inclined edges 34 mate with complementary 45" inclined edges 36 defining the open mouth of the housing 22. The lid 32 thus fits on the housing 22 as a flush fit.

Figures 4,5 and 6 show an alternative design for the housing 22. The housing 22 has three of the slits 24 and it will also be seen from Figures 5 and 6 that the housing 22 is provided on its inside with abutment means in the form of knobs 28. The knobs 28 are for receiving a printed circuit board such as the printed circuit board 12 shown in Figure 1. The knobs 28 can be formed as small isolated units as shown, or depending upon the method of formation of the housing 22, they can be formed as pillars extending to the top 26 of the housing 22.

As can best be seen from Figure 6, the slits 24 are larger attheir bases than at their top, in order to facilitate the passage through the slits 24 of the attenuator pins 16.

Figures 7,8 and 9 iilustrate a lid 32. The lid 32 is provided with four small pillars 38 which are for location on appropriate knobs 28. As can be seen most clearly from Figure 9, the periphery 40 of the lid 32 is chamfered but that it locates easily in a correspondingly chamfered top of the housing 22.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected. Thus, for example, a different type of abutment means to the knobs 28 may be employed.

Also, a different type of foam material to the polyurethane foam material 30 may be employed. If desired, the foam material may be omitted altogether.

Claims (10)

1. Attenuator apparatus comprising first and second resistor networks which are provided on at least one substrate, and a switching matrix of attenuator pins, the attenuator pins being for receiving connector means, the connectors means being connectible between different attenuator pins to place appropriate parts of the first and/or second resistor networks in circuit to afford different desired attenuation values, the first and the second resistor networks, the substrate and the switching matrix of the attenuator pins all being mounted on a printed circuit board and all being housed in a housing, and the housing having inwardly projecting abutment means against which the printed circuit board rests in order to position the printed circuit board in the housing.

2. Attenuator apparatus according to claim 1 in which the abutment means comprises a pluraiity of knobs.

3. Attenuator apparatus according to claim 2 in which there are four of the knobs.

4. Attenuator apparatus according to any one of the preceding claims in which the housing is closed buy a lid.

5. Attenuator apparatus according to claim 4 in which the open end of the housing and the lid have complementary inclined mating surfaces for enabling the lid to be a flush fit on the housing.

6. Attenuator apparatus according to any one of the preceding claims in which the inside of the housing is provided with a plastics foam material.

7. Attenuator apparatus according to claim 6 in which the plastics foam material is polyurethane foam material.

8. Attenuator apparatus according to any one of the preceding claims and including the connector means.

9. Attenuator apparatus according to claim 8 in which the connector means are two section electrical shortening links, each link having a pair of end caps for fitting over a pair of the attenuator pins, and the links being usable in pairs.

10. Attenuator apparatus substantially as herein described with reference to the accompanying drawings.