| 摘要 |
<p>1462814 Compensating a comparator COULTER ELECTRONICS Inc 16 April 1974 [16 April 1973] 16645/74 Heading G1A In an arrangement for compensating for the inadequate high frequency response of a comparator 14 which results in a delay on its output, the delay effect is mitigated by a compensating circuit 18, comprising a capacitor 42 and resistors 44 and 46 connected, as shown, to one input 30 of the comparator 14, the other input 28 being connected to a photo-responsive device 12. The apparatus is intended to be used for measuring the concentration of a substance in a liquid. The voltage output of the photo-responsive device 12 due to radiation received after passing through a clear solution of liquid is taken as the reference voltage. Such a reference voltage is applied via a switch 32 to a voltage storing circuit 16 and charges the capacitor 24. During measurement of an unknown liquid switch 32 is opened and a further switch 34 is closed and a logic output signal 1 is provided by the comparator 14, while the capacitor 42 discharges, until the voltage to input terminals 28 and 30 are equal, the duration of the pulse thereby providing information about the liquid concentration. The presence of the resistance 46 compensates for a delay introduced by the comparator 14 by providing an effective delay, Fig. 2 (not shown) to the capacitors exponential output and thereby compensates the output signal of the comparator 14. When the logic signal output from comparator 14 is no longer "1" a control circuit 20 senses this and closes switch 32 and opens switch 34. This enables the capacitor 36 to be recharged for the next measurement.</p> |
