| 摘要 |
The invention proceeds from a signalling device for monitoring a space for temperature changes, which consists of a radiation receptor, which has at least one detector with at least one sensor that receives the electromagnetic radiation and an integrated field-effect transistor, as well as a downstream linear amplifier and means for compensating the frequency response of the sensor output level, an evaluation circuit for triggering an alarm in the event of a change in radiation intensity, and an alarm unit. In order to improve the signal-to-noise ratio and thus the noise immunity in as simple and cost effective a way as possible, the field-effect transistor is co-used as an active subassembly of an equaliser amplifier connected to the sensor. For the purpose of complete compensation of the drop in output level of the sensor in the direction of higher frequencies, in the case of devices with a large range and thus a large bandwidth it is proposed for the equaliser amplifier to be designed with at least two stages, the slopping position of the gain being effected, on the one hand, by a frequency-dependent negative feedback between the two stages and, on the other hand, by a series RC element between the emitter of the transistor of the second stage and the positive pole of the feed voltage source.
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