"As the Internet giants have set off a wave of hardware" remodeling ", science and technology is gradually returning to nature, and people are more and more aware of the charm brought by science and technology in real life. Not long ago, aiban.com got a creative self generating doorbell product. As we all know, at present, doorbell products are not uncommon. It can be said that they have rotten the street, and there will not be too many people to pay attention to. However, this self generating doorbell product is quite creative. With the selling point of "self generating", it has attracted everyone's attention. Let's take you to understand this product.
Linbell appearance
Self generating wireless doorbell linbell is the first product for end consumers launched by Wuhan lingpu technology, which aims to provide users with a comfortable and convenient doorbell system. Wuhan lingpu technology is a company mainly committed to providing smart home / smart building products, basic modules and solutions based on energy collection technology. It can be imagined that linbell can be regarded as a product bred by lingpu Technology (see the figure below).
Linbell box
Linbell packing box adopts environmentally friendly Kraft linerboard with no extra printing. It is a very environmentally friendly design. The size of the whole packing box is 220mm * 125mm * 55mm and weighs 287g. The rubbing on the front of the packing box is really a sample of the product, and some function introductions of linbell are marked on the side. There is a QR code bar code of lingpu technology company at the bottom. From the appearance of the whole packing box, linbell pays great attention to product details and feels very sincere. OK, open the pull-out packing box and take out the contents (see the figure below)
All samples in linbell box
The contents of linbell's box are clear at a glance:
Doorbell transmitter * 1
Doorbell host * 1
Instructions, double-sided tape, screw
Next, we will mainly focus on the door bell transmitter and the door bell host, and other accessories will not be described.
Doorbell transmitter
Doorbell host
Both the door bell transmitter and the door bell host are ivory white. The material feels very thick. The overall square structure has the same length and width of 83mm. The thinnest part of the transmitter is only 8mm, which is almost as thin as an ordinary electric light switch base. From the product introduction, it is known that the transmitter generates power by coil, and the transmitter switch that can generate power by coil is so light and thin, It can be regarded as an embodiment of design strength. Due to the structure of the receiver, it should be thicker, about 21mm. Due to the embellishment of LED and function keys, this sense of massiness gives people a strong and reliable sense of art. Although the thickness difference between the transmitter and the receiver is obvious, the weight of the two machines is almost the same, one is 65g and the other is 80g, which is about the same as that of a mobile phone.
The transmitter looks simple, with only one doorbell button, covering almost the whole front, just like an ordinary doorbell. Similar LED decorative lights on the keys are of no practical use. The back of the transmitter doesn't look ideal. First of all, a red wire (which should be the antenna) is very conspicuous. The "core module" is embedded in the switch, and the color difference is obvious. As for the symmetrical two holes, they are screw holes for fixing the transmitter.
Compared with the transmitter, the receiver looks good. There is a circle of three function keys wrapped in plastic in front. When the keys are operated or the doorbell is triggered, the blue LED effect will be lit, especially at night. It is very beautiful. The back is a standard two interface 220V plug, three fixing screws and the horn can be seen vaguely from the horn hole.
We have a general understanding of the appearance of linbell. Let's simply use it. Insert the receiver into a 220V socket and press the transmitter switch. The following figure is the author's simple demonstration effect.
Linbell effect
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Every time you press the transmitter switch, the doorbell can respond. When I try it, the effect is 100% (> 200 times), which is very good. In addition, we can customize the doorbell system through the three buttons of the receiver:
Mute key: Enter / exit the mute effect. Long press to check the code
Volume key: increase or decrease the volume
Music key: you can switch different doorbell music (25 chord music optional)
Linbell's mute key can achieve the effect of one button mute, which is very practical in life. For example, if you drag your tired body home and want to be quiet, you can press linbell's mute key, or your baby has fallen asleep safely and doesn't want the doorbell to disturb the baby's sleep. At this time, one button mute is very convenient and suitable, because one button mute only disables the bell If someone rings the doorbell, the corresponding LED will flash, as shown in the figure above, so you won't miss important visitors.
Of course, in addition to these explicit functions, linbell has more implicit matching functions. When the power is on, long press these three keys to clear the code matching (Communication) between the receiver and the transmitter, and press and hold the mute key to add the code matching (see linbell's Manual for specific operation, which will not be described in detail here), so that one transmitter can match multiple receivers, which will be the benefit of the local tyrant house.
After reading and using linbell, I'm surprised. Just like the product introduction, it's beautiful and easy to use. The author didn't find any "chain falling" in the process of use. Let's continue to go deeper and disassemble linbell to see what's inside.
Linbell disassembly
launcher
First impression, if I have a little opinion on the back appearance of the transmitter, I'll dismantle it first. Because the transmitter itself needs to be fixed by screws, the design is similar to that of an ordinary light switch, and the shell can be removed with a little force.
Disassemble the transmitter
In order to save time, the process will not be described step by step. Anyway, it is easy to dismantle it as shown in the figure above. As previously guessed, the red wire is the antenna. Continue to remove the cover of the core module, and you can see the circuit board of the transmitter.
Transmitter core module
From the circuit board, we can see that the transmitter has actually made four compatible keys, which is easier to understand. After all, the keys of the doorbell will be repeatedly "trampled", which can be said to leave a step for four times of insurance for subsequent possible key failure. But in fact, due to the structure, only one specific key can be used after assembly, and the other three are useless. Is it reserved for debugging? Or will the structure be adjusted in the future? I don't know. From the opening of the circuit board, you can see the core of power generation - coil.
Seeing the coil, the friends with good physics scores in middle school immediately reacted, and the principle of self generating electricity was also broken -- electromagnetic induction. Further, each operation of the transmitter button is like cutting the magnetic induction line, so that the copper wire coil generates current. In fact, the mechanical operation of this part of the coil can also be removed, but there is nothing to study deeply. In order to prevent the hard removal from damaging the key device, the author will not do this kind of icing on the cake. Through careful observation, it can be seen that the two contacts on the coil are just the power supply circuit interface against the PCB board, which is amplified by the amplification circuit to supply power to the controller.
When it comes to the controller, we found that there is only one chip on the transmitter circuit board. In order to control the transmission, it is not difficult to guess that this is an SOC chip integrated with control and RF. The hardware block diagram of the transmitter circuit is given below. Capable friends can DIY their own scheme.
Linbell transmitter hardware block diagram
receiver
Of course, it is of little practical significance to simply discuss the transmitter circuit. We need the corresponding receiver circuit to call it a complete product. We will continue to look at the linbell receiver later.
Compared with the transmitter, the disassembly of the receiver is really simple. Unscrew the three screws at the back and break the transmitter shell with a little force (see the figure below)
Receiver disassembly
As can be seen from the above figure, linbell's receiver is mainly connected by two PCB boards through wires, which can be simply divided into reception control part and power supply part.
The reception control circuit seems to be rich in content, and we will focus on it (see the figure below).
Receiving control part circuit
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From the signal entry process, taking the blue receiving antenna as the starting point, the 433MHz signal enters the RF chip along the antenna. After processing, the analog signal is converted into a digital signal and enters the microcontroller, and then the microcontroller controls the DAC decoding chip. The music embedded in the DAC decoding chip is amplified through the audio power amplifier 8002a, and then sounds through the horn.
Let's take a closer look at the core interaction mode of the whole circuit, that is, the communication between transmitter and receiver through 433MHz frequency. What are the characteristics of 433MHz frequency and why linbell uses 433MHz frequency as linbell's communication frequency.
First of all, 433MHz frequency is classified as ism unlicensed frequency band, and the advantage of this kind of products is that the frequency band used by mobile phones does not need to pass the network access license to be normally sold on the market, so the first advantage of 433MHz frequency is to use it immediately.
Second, the linbell doorbell system has a small amount of data transmitted wirelessly. Considering that the communication between doorbells has to go through layers of barriers, from the starting point of its own product design, the signal penetration ability and propagation range should be considered first. In addition, the standby power consumption must also be considered. After all, the doorbell belongs to such a system with real-time power on. Generally speaking, compared with other wireless schemes, For example, WiFi and Bluetooth have obvious advantages, so it is reasonable for linbell to choose 433MHz band.
OK, after a brief understanding of the characteristics of the 433MHz frequency, let's take a look at linbell's microcontroller. The doorbell system is a very simple control system without any special complex functions, so the selection of microcontroller should be as reliable and applicable as possible. However, in the current market, 8-bit MCU still accounts for a certain proportion in small household electrical appliances. The selection of design scheme can be considered from this aspect.
In fact, the microcontroller is not very important in the function realization of the doorbell. What deserves our attention is that the DAC decoding chip tq8025 produced by tianqin electronics integrates almost all the functions of the doorbell (except transmitting and receiving).
8 chord 25 music
Three function keys
Direct output of audio
Perhaps after reading the functions of this DAC chip, we have more questions. Since the audio can be output directly, why add an audio power amplifier? Here, I also appreciate the attitude of lingpu technology to make products, coupled with the audio power amplifier, which greatly increases the output of doorbell music effect to a certain extent, ensures the excellent quality of products, and allows users to experience the most intuitive and intimate use experience. Although the yingruixin bridge audio amplifier 8002a used by linbell is not a particularly high-end product, it is more than enough to be used as the audio amplification of the doorbell system here.
Finally, look at the power supply. In fact, there is nothing to say, that is, the design scheme of a 220V AC to 5V direct power supply module is adopted (see the figure below)
220V AC to 5V DC power supply module
Looking at the whole receiver, do you feel suddenly enlightened? In fact, the wireless doorbell system is indeed a simple communication system. It is very simple to make, but it wants to be refined. Due to the complexity and unpredictability of wireless communication, the product needs continuous debugging and verification in order to achieve a satisfactory level. As for the self generating wireless doorbell of lingpu technology, it still needs a wide technical threshold, which should also prove that lingpu technology has made achievements in the field of energy collection. The following figure is the hardware block diagram of the receiver for the reference of interested friends.
Receiver hardware block diagram
Finally, let's talk about the use experience. Linbell of lingpu technology is indeed an innovative product to improve people's lifestyle. For example, an intelligent router appeared last year. The situation is similar, that is, it uses the well-known simple hardware carrier to create novel and creative products, which is also the differentiated development way of many innovative companies. Lingpu technology's linbell self generating doorbell system is commendable. Using coil self generating can also make the transmitter so thin and intimate one button mute function. It is worth trying regardless of product workmanship, quality and humanized function design. At present, this product has a reservation on the roll call time, and the price is about 150RMB, Like friends can go to support.
[weekly review] the third issue of linptech's sincere work - disassembly of self generating wireless doorbell linbell
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