| 摘要 |
1. Circuit arrangement intended to be connected to a telephone exchange for monitoring the variation of the potentials on a plurality of lines (1) or of the potential differences on a plurality of pairs (30) of lines with respect to the exceeding of or falling below a single specific threshold value by the individual potentials or potential differences, in which arrangement both binary values are produced with the aid of at least one comparator (9; 41, 42) and of a fixed reference potential (24) as a function of the monitored potentials, and also a multiplexer (3, 5; 3, 32), which enters into relationship with the individual lines (1; 30) in cyclic sequence, is disposed on the path between the lines and an output (18) for the said binary values, characterized in that the comparator(s) (9; 41, 42) is(are) contained in a single central test apparatus (21) disposed between the multiplexer (3, 5; 3, 32) and the output (18), that the test apparatus (21) contains an operational amplifier (7; 36, 37) producing a measuring potential (23) proportional to the potential or the potential difference of the line (1) or the pair (30) of lines connected thereto via the multiplexer (3, 5; 3, 32), that the multiplexer (3; 3, 32) is an analog multiplexer, and that there are circuit means (10, 11, 12, 13, 14) present which are digitally adjustable in large and small steps and which produce the reference potential (24) as a potential bearing a specific, permanently adjusted relationship to a supply potential (-), the reference potential (24) being permanently adjusted in conformity with various types of telephone exchanges sometime prior to installation. |
