Application of DNL9308 in the field of digital display automatic control

Photocoupler

1. Drilling Pressure Control Alarm System: In geological drilling, the pressure applied to the drill tool should remain within a specific range—between 1200kg and 1800kg. If the pressure exceeds or falls below this range, it indicates an abnormal condition in the drilling process or that the tool is encountering different types of rock formations. This system uses the DNL9308 to monitor and trigger alarms when these conditions occur. We set comparator A to 1800 and comparator B to 1200. The alarm circuit is formed using the output signals from state output ports C > A and C ≤ B (as shown in the diagram below). While the pressure sensor and control circuit details are omitted for brevity, readers can refer to related technical documentation for more information.

2. Thermostat Controller: When high precision is not required, the DNL9308’s C port can be used to control temperature. For example, in a heat treatment furnace operating between 760°C and 780°C, we set comparator A to 780°C and comparator B to 760°C. Using two sets of electric heaters, the system ensures stable temperature control. When the temperature drops below 760°C, the signal C ≤ B triggers relay J1 to turn off the auxiliary heater. As the temperature rises above 780°C, the signal C > A activates the heater again, maintaining the desired range. This approach allows precise and efficient temperature regulation.

3. Cryogenic Chamber Temperature Control: (1) One application involves controlling temperatures between -45°C and -50°C. Comparator A is set to -50°C, and comparator B is set to -45°C. As the temperature fluctuates, the system monitors whether C ≥ A or C < B. After power-on, a capacitor (1μF) generates a positive pulse at point A, causing the relay to activate until the temperature reaches -50°C. At point B, a reverse pulse resets the bistable, releasing the relay and allowing the temperature to rise. When it reaches -45°C, the cycle repeats, keeping the temperature stable. (2) Another setup controls temperatures between +3°C and -20°C, with comparator A set to +3°C and comparator B to -20°C. The system continuously adjusts based on the C > A and C < B signals to maintain the desired range.