Based on the photosensitive element and control circuit technology, the working principle of a light-sensing power-saving controller is described, and the circuit diagram is drawn. After actual inspection, the controller can be applied to the lighting system of school classrooms and laboratories, which plays a role in environmental protection and energy saving and prolongs the service life of the lamps.
At present, the lighting of most school classrooms still uses manual control switches, but often due to people's lack of awareness of power saving and neglect of management, even in the case of abundant natural light, the bright light in the classroom can still be seen everywhere, not only losing energy, At the same time, it also reduces the service life of the lamps, which is a waste of resources. In order to solve this problem, the author combined with the actual situation, after many experiments, designed and produced a light-sensitive power-saving controller for the school classroom lighting circuit, used in classrooms and laboratories, with good results.
1 function effect
According to the daily teaching and self-study of the school, if the sound control and the infrared detector are not installed, if the light control is solely used, the night light will not be automatically extinguished. Therefore, the light-sensing automatic control circuit and the manual button can be used to control the classroom lighting. When the indoor natural light reaches the normal teaching requirements, the lights are automatically extinguished; on the rainy days and evenings, after the indoor light level drops to a certain level, the lamps can be manually turned on as needed.
2 controller composition
(1) Mains conversion. The 220 V AC is converted to a 12 V DC power supply that can be used by the light sensing control circuit by step-down, rectification, and filtering.
(2) Natural light detection components. A semiconductor device that converts an optical signal into an electrical signal using a photodiode is a key component in the controller. It should be noted that the component must be placed outside the range of the light in the classroom and used only to detect the intensity of natural light. Because some professional courses teach special requirements for light, this requires the component to be based on actual needs. Adjust the sensitivity of its natural illuminance.
(3) Anti-interference circuit: The design of the controller must also take into account the interference of external clouds such as lights or external light such as lights and lightning on the natural light detection components. It is necessary to add an output delay circuit to prevent interference. When receiving external interference, Ensure that the flip-flop circuit does not flip under transient interference.
(4) Time-base circuit NE555.NE555 is a kind of 555 series timing component. It is cheap and stable. As a control component, the photodiode will change the internal resistance of the photodiode due to the change of illuminance, causing the change of the trigger voltage of the time base circuit NE555. When the voltage is lowered or raised to a certain threshold, the time base circuit outputs corresponding high and low levels, turns the illumination indicator on or off, and causes the relay to pull in or release.
(5) Relay components. Since most school classrooms use fluorescent tube lighting instead of incandescent lamps, the negative inductance effect when the fluorescent tube is turned on causes the overshoot voltage to be high, which can burn out the thyristor device. Therefore, it is necessary to use a relay to control the lighting power supply.
3 circuit design and working principle
The light-sensing power-saving controller circuit is shown in Figure 1.
Figure 1 Light-sensitive power-saving controller circuit diagram
First, it is necessary to perform T-buck, IC1 bridge rectification and C1 filtering on the mains, convert 220 V AC to 12 V DC, and use LED D1 as the power on/off indicator. 12 V DC is divided by photodiode D2 and resistors R2 and R3 and applied to pins 2 and 6 of time base circuit NE555. When the natural illuminance of the room decreases, the internal resistance of the photodiode D2 gradually increases, and the voltage of the 2nd and 6th pins of the time base circuit NE555 gradually decreases. When it drops to 1 / 3 V CC , the time base circuit IC2 outputs The state is reversed, and the 3rd pin will output a high level, so that the transistors V1 and V2 are saturated and turned on, and the light-emitting diode D4 is powered and illuminated. The function of the light-emitting diode D4 in the circuit is an illumination indicator light, which indicates that the indoor light is dark. Allow the light to be turned on; at this time, press the switch N1, the power will be applied to the base of the transistor V3, so that V3 and V4 are saturated and turned on. At the same time, the V4 collector voltage is fed back to the V3 base through the resistor, and V3 and V4 remain conductive. The state ensures that the relay J is sucked and self-protected, and the lighting circuit in the classroom is turned on, and the light is turned on; when the lamp needs to be turned off, the switch N2 is pressed, the transistors V3 and V4 are turned off, the relay J is released, the lighting circuit is cut off, and the light is extinguished.
When the natural illuminance of the room gradually becomes stronger, the internal resistance of the photodiode D2 gradually becomes smaller, and the voltages of the 2 and 6 pins of the time base circuit NE555 gradually increase until the 2 feet of the signal rises to 2 / 3 V CC . The level is such that the transistors V1 and V2 are cut off, the latter circuit is powered off, the relay J is released, the light source circuit in the classroom is disconnected, and the light is automatically extinguished.
In order to prevent the nighttime lightning, lights and other moments of strong light from illuminating the photodiode D2 to disconnect the lighting circuit in the classroom, C2 should use a capacitor with a larger capacity; at the same time, to improve the reliability of the circuit, add capacitor C3 to prevent external interference; There is a certain lag time in the process of going to break and breaking to pass. Adding resistors R5 and R6 to the circuit, and appropriately reducing the resistance, the lag time is shorter.
4 Production, commissioning and installation
(1) Production. The components were soldered to the board, and a 6 cm × 9 cm board was found to be suitable. After the soldering is completed, the board is placed in a properly sized housing that is preferably inexpensive and easy to purchase and remodel. It should be noted that the power indicator D1 and the illumination indicator D4 should be exposed outside the plastic box to facilitate the switching operation by the indicator light.
(2) Commissioning. Mainly adjust the adjustable resistors R2 and R6 in the circuit. When adjusting, the illuminance meter needs to accurately measure the illuminance: When the indoor natural illuminance drops to the required illumination (150 LUX), R6 is adjusted from bottom to top until the illumination indicator D4 emits light; When the indoor natural light reaches the teaching requirement (200 LUX), R2 is adjusted from bottom to top until relay J is just released, and illumination indicator D4 is off (3). In actual installation and use, you need to pay attention to the following two points:
1) Light-sensing control component installation position: First of all, to ensure that the photodiode can not be illuminated by the indoor light source, so it should be installed in the window position, the direction of the direction is toward the outdoor natural light, so that it can effectively collect the light in the natural environment. . In addition, it is necessary to take into account the influence of shadows on the photosensitive components in different time periods of buildings and trees, and adjust them to the optimal position.
2) Self-reset button switch N1 and N1 installation position: It can be modified by using the original wall switch position, and two holes are drilled in the original wall switch panel for circuit wiring installation. When the light in the classroom is not enough, D4 lights up, and the indoor light is turned on. After the class is finished, press N2 and the indoor light goes out.
5 Conclusion
The well-made controller theory controls the power ≤5 kW, and the actual control classroom has 4 channels of 16 fluorescent lamps, which are used in 24 classrooms of one teaching building. After nearly half a year of use, the light-sensing power-saving controller The performance meets the design and usage requirements, which not only saves electricity, but also greatly reduces the maintenance of lamps and switches in the classroom. The controller can be applied not only to the lighting circuits of various school classrooms and laboratories, but also to offices, corridors, street lamps, etc., and has good promotion value. At the same time, such as the addition of voice control, infrared remote sensing control and microcontroller program control, etc., can also achieve more intelligent automatic control effect.
What is a wireless AC controller? What does it do?
Wireless AC controller is a kind of network device, such as the AC100/150 of Fengrunda, which can be used to centrally control and manage wireless aps. It is the core of a wireless network and is responsible for managing all wireless aps in the wireless network. AP management includes: delivering configuration, modifying related configuration parameters, RF intelligent management, and access security control.
Why use a wireless controller, and what exactly does it do?
In fact, the role of the wireless controller is to play a gateway function between the WLAN and the Internet (on the router), and the data from different access points are aggregated and accessed to the Internet. The role of an access point (AP) is to complete wireless access, and it can control user access through network flags.
The role of wireless controllers
1, Flexible networking mode and excellent scalability
The AP does not need to be directly connected to the AC, so that the AP can be deployed in any place that needs to be covered through the network, such as you deploy an AP in each employee's home, and then connect to the wireless controller inside the enterprise through the VPN, you can expand the wireless network of the enterprise to the family of each enterprise member.
2, intelligent RF management functions, automatic deployment and fault recovery
Through the dedicated RF management module, we can initially estimate the AP deployment according to the user's architectural design drawing, and can calculate the average bandwidth of the wireless terminal, the coverage between AP and AP in the actual debugging process.
3. Centralized network management
All the configuration of the wireless network can be completed by configuring the wireless controller. For example, enable, manage, and maintain all AP devices and mobile terminals, including all functions such as radio wave spectrum, wireless security, access authentication, mobile roaming, and access users.
4, powerful roaming function support
The wireless controller uses AP as the boundary combined with fast RF management system, which greatly reduces the connection time between wireless client and AP, and thus realizes the function of fast roaming.
5. Load balancing
AP and wireless controller systems can distribute wireless users or terminals to nearby aps within the coverage area of an AP, ensuring the number of each wireless terminal or the sum of AP bandwidth transmission or the upper limit of each wireless terminal bandwidth.
6, wireless terminal positioning, rapid fault location and intrusion detection
Wireless controllers can track and locate the location of wireless terminals, such as wirelessly connected computers, PDAs and Wi-Fi mobile phones.
7, powerful access and security policy control
At present, the wireless system supports authentication of 802.1, WEB authentication, MAC, SSID, VPN, etc., and supports various encryption modes such as WEP, WPA, WPA-PSK, WPA2, etc., and all configurations can be configured globally through the wireless controller.
8, Qos support
AP and wireless switching systems can limit the maximum bandwidth of a user's wireless connection within each user's privileges. For different IP services, the system can also define different QoS queues through the wireless switch module. For example, for wireless voice applications, SIP and RTP protocols can be set in the high queue, while common applications such as http and ftp can be set in the low queue.
The wireless controller AC is more advanced than the AP, plays the role of manager in the wireless network, and the wireless controller AC also acts as a client to complete a series of functions in the wired network (such as authentication, authentication, etc.). However, wireless controller AC is not a WLAN device specified in the 802.11 protocol family, but as a supplement to the protocol in specific applications, and its price far exceeds that of ordinary access point (AP) devices.
In small-scale wireless networks that use only a few aps, it is not economical to use expensive wireless controller AC equipment. However, if the number of wireless aps is large, more than 20 can be used AC controller.
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