| 摘要 |
A device for control of flow rate of liquid in pipeline comprises a wire heater, first thermo-element the first terminal of which is connected to the second terminal of the first resistor, and the second terminal – to the first terminal of the second thermo-element, at that the second terminal of the second thermo-element is connected to the second terminal of the second resistor, and the first terminal of the second resistor is connected to the second terminal of the third resistor, the first and the second terminals of the third resistor are connected to the frequency converter. The frequency converter includes the fourth, fifth and sixth resistors, the first, second transistors and a bipolar transistor, the first and the second capacitors, two sources of direct voltage. The second terminal of the first source of direct voltage is connected to the collector of the second transistor the base of which is connected to the second terminal of the fourth resistor and the first terminal of the fifth resistor, and the emitter of the second transistor is connected to the emitter of the first transistor. To the base of the bipolar transistor the second terminal of the first capacitor and the first terminal of the sixth resistor are connected, besides that the collector of the bipolar transistor is connected to the second terminal of the sixth resistor and the first terminal of the second capacitor, and the emitter – to the first terminal of the first capacitor. The first and the second terminals of the second source of direct voltage are connected to the first and the second terminals of the second capacitor, respectively, at that the first terminal of the first source of direct voltage is connected to the first terminal of the first resistor and the first terminal of the third resistor. The base of the first transistor is connected to the second terminal of the third resistor and the first terminal of the second resistor, the output of the device is formed with the collector of the first transistor and the common bus. |
