| 摘要 |
1, 195,579. Voltage testing. COMPAGNIE DES COMPTEURS. Dec. 7, 1967 [Jan.12, 1967], No. 55794/67. Heading G1U. To successively measure the D. C. outputs of several thermocouples P 1 , P 2 , &c. and also provide an instantaneous alarm if any is in error, the outputs are coupled to respective terminals A 1 , B 1 , A 2 , B 2 , &c. of the input switch of a multi line recorder E and also to respective alarm units S 1 , S 2 , &c. incorporating low input impedance transistorized chopper amplifiers F and alarm circuits K, W. The recorder switch has three simultaneously operated wipers M 1 , M 2 , M 3 , of which two, M 1 , M 2 , successively select pairs of input terminals for connection to the recorder, while the third M 3 , connected to M 2 , short circuits the input terminals BC of the respective amplifier F. This connects the terminal B to the base of a transistor in the chopper stage of the amplifier so as to increase the input imedance of that amplifier, so that circulating currents in its input stage do not falsify the values of the corresponding input recorded by the recorder. The input to each amplifier is fed in opposition to reference voltages U 1 <SP>1</SP>, U 2 <SP>1</SP>, etc., the alarm W in the amplifier output being operated if the thermocouple outputs U 1 , U 2 , &c. differ from the reference voltages significantly. A delay circuit D prevents the alarm W from operating during the short periods when the input impedance is raised during connection to the recorder. |
