Long-haul carrier frequency transmission controller - has two NTC resistors indirectly heated by same current and driving amplifier of switching transistors

摘要

The supervision relates to a control circuit of an indirectly heated NTC resistor acting as a controller of carrier frequency long-haul traffic and ensures that bottom and top variation limits are not overrun. This is achieved by a comparison NTC resistor RHV heated by the same currents as that for the main NTC resistor RHS. The sensing and measuring loop turns on transistors (TS1) or (TS2) when the limits of control are reached. - The measurement is controlled by a difference amplifier (DV) fed from a voltage divider, the output voltaga of the amplifier used to switch a transistor into the blocking state.