Many electronic devices require a regulated DC power supply with high precision and large current. This paper introduces a general-purpose low-power voltage regulator integrated circuit uA723, which is equipped with a suitable high-power tube and other peripheral components, and is composed of a high-power adjustable DC stabilized power supply with an output current of up to several tens of amps.
uA723 mainly plays the role of voltage regulation and voltage regulation in the circuit. Its internal structure is shown in Figure 1.
Figure 1 uA723 internal structure diagram
Figure 2 High-power adjustable power supply circuit diagram
Figure 2 shows the schematic diagram of the high-power adjustable power supply circuit. Its working principle is as follows:
uA723 itself is a series adjustable regulator; its characteristics are controllable output voltage Vo=2～37V, output current Iom=0.15A; small output temperature drift, high ripple rejection ratio, short circuit current limiting protection Wait. Similar to the uA723, there are LM723, HA17723, CW723, W723, and the like. They are available in metal round-shell Y-10 packages and dual in-line C-14 packages. The pin functions are different in different packages and should be distinguished.
This circuit adopts uA723 in C-14 package. Its 8-pin Vref terminal is internally connected with a 6.2V voltage regulator and a voltage divider resistor to form a reference voltage circuit. The 4-pin is an inverting input terminal, also known as a sampling terminal, which changes the external connection. The resistance of the 10k potentiometer can change the output voltage of the 10-pin. The 10-pin voltage output value determines the Veb potential value of the external expansion sampling tube VT5 of the uA723 and its conduction amount, thereby controlling the output values ​​of the four parallel high-power adjustment tubes VT1-VT4. C3 is an external damping capacitor, Rsc is a short-circuit current limiting protection resistor, which can limit the output current of uA723; current limit value ILM=Vse/Rsc (Vse-current limiting resistor voltage value); capacitors C7, C8 improve hum Bypass capacitor, R1 is the bleeder resistor, which acts as a stable voltage.
Conclusion
The circuit has the advantages of simple structure, convenient maintenance and good voltage regulation effect, and is almost unaffected by fluctuations of the AC voltage and load current of the power supply network. As long as the quality of the device is guaranteed, it is usually not easy to malfunction. Once the uA723 is damaged, the output voltage may be high or there is no output voltage. Just replace it with a new uA723 and re-commission the output to get back to normal.
Thermometers include bimetallic thermometers, pressure thermometers and marine thermometers, which are suitable for detecting and controlling the liquid level of containers in shipbuilding and other industries.Bimetallic thermometer is a field detection instrument for measuring medium and low temperature. It can directly measure the temperature of liquid steam and gas medium in the range of - 80 ℃ - + 500 ℃ in various production processes. The main element of industrial bimetallic thermometer is a multilayer metal sheet composed of two or more metal sheets, which works based on the principle that two different metals have different expansion degrees when the temperature changes. It is composed of a bimetallic sheet wound into a circular bending shape. When one end is heated and expanded, the pointer is driven to rotate, and the working instrument will display the temperature value corresponding to the thermal potential.
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