The principle of wireless remote control doorbell and the traditional doorbell are wired doorbell, which is convenient to use and greatly facilitates everyone's life. If you are in a big yard, or a homeowner who often can't hear the doorbell, sometimes you will not receive visitors in time, which is very embarrassing. This paper introduces how to make a wireless remote doorbell, which is convenient for the owner to use anywhere in the room. Install the doorbell button on the door. As long as the visitor presses the button, the reception host in the living room, kitchen or bedroom will sound "Ding Dong" or music, which is loud and pleasing to the ear, informing that a guest is coming. The distance ranges from several meters to tens of meters, generally 15 to 20 meters away. The receiver is powered by two No.5 batteries, and the measured standby power consumption is =0.48mA at 3V, which prolongs the service life of the batteries. The physical object is shown in the following three pictures. The dimensions are: transmitting 7.8cmX4.6cmX 1.6cm, receiving 8.8cmx6.1cmx2.4cm. The original package contains 12V A23 battery for the key. Select the switch on the upper part of the receiving box through music. The storage box can be hung on the wall or placed vertically. This effect will be achieved. The following unlimited electronic production network (Jiang Jieping) introduces the production method of this doorbell in detail. Material preparation: The transmitter needs a micro inductor of CD 4069,9018, 10, a 32.768kHz crystal, a battery of 12VA23, a normally open button and some resistance-capacitance elements. The components required by the receiver are CD4069, 90 18, 90 13, 32.768kHz crystal, 10 micro-inductor, 1X2 toggle switch, a two-tone music piece, a small buzzer and several resistance-capacitance components. Figure:/Article/Uploadfiles/200608/Menlin5.jpg/Article/Uploadfiles/200608/Menlin6.jpg Principle (the numbers of pictures and texts are inconsistent, so readers can proofread them themselves) To make a wireless remote doorbell, we must first understand its working principle. Please look at the attached drawings. The transmitter consists of modulation oscillation stage and high frequency oscillation stage. The modulation stage circuit is completed by cheap domestic CD4069 and 32.768KHz crystals. CD4069 is a 6-inverter. An inverter means that each phase shifter has two terminals. When the input terminal is at high level, the output terminal turns to low level; When the input is low, the output is high, and the levels of the input and output are always opposite. Pin 1 and pin 2 are the first inverters, as shown in Figure 65438. This paper calls it inverter 1, followed by inverters 2, 3, ..., with a total of six ***CD4069. When the transmitter switch is pressed, inverters 1 and 2 and related components form an oscillation generator to generate a low-frequency signal of 32.768KHz. The process: the 1 pin of inverter 1 starts to be low, the 2 pin is high, and the 4 pin is also high. The high level of pin 2 charges the crystal X 1 through R2, and the charging current reaches the negative electrode through pin 4 of R2-X 1- inverter 2. The charging time is determined by X 1, and the equivalent capacitance is 200P p. Due to the charging of X 1, the voltage on X 1 gradually rises, and the Zuo Zheng is negative to the right. When it rises to the inverted level of inverter 1, two pins change from the original high level to low level, and four pins also change to low level at the same time. X 1 starts to discharge, and the discharge path is R2- inverter 1 2-pin negative electrode. After discharge, the potential on X 1 drops to a certain extent, the pin of 1 drops to a low level, and the output terminal turns to a high level to charge X 1 again. At this point, a charging and discharging process has been completed, that is, an oscillation period, and the four pins output low-high level changes. After that, the oscillation will continue, and the four pins of inverter 2 will always output level signals with high variation. The frequency of this signal is determined by the crystal; It is decided to be 32.768kHz. When the circuit actually works, the above process will be completed soon. Inverter 1 and inverter 2 are used to generate oscillation signals, and inverters 3-6 are used in parallel to form output control, which can provide injection current of 20-30mA. The output terminals of inverters 3-6 are connected to the emitter of emission tube Q 1, which modulates the amplitude of Q 1 and emits electromagnetic waves. The capacitors of Q 1, L 1, C3 and 6P form a high-frequency oscillator, and the oscillation frequency is determined by the printed inductors L 1, JC3 and the junction capacitance of the transistor's collector. Generally 200-270MHz. If the emitter of Q 1 is directly connected to the negative electrode, it can generate a constant-amplitude high-frequency wave, which is then connected to the output end of the inverter, so that the output is modulated by an oscillation signal of 32.768KHz, and the signal is emitted through the printed inductor. Every time the key is pressed, it is fired. Q3, L3, C4 and C5 are super regenerative oscillation receivers, L3 is winding coil, which is wound on a skeleton with a diameter of 5mm, with 3 turns of 0.5 1 enameled wire, and the middle of the skeleton is adjusted by copper core. When the oscillation frequency of L3 is the same as that of the transmitter, the super-regenerative signal of Q3 is controlled by the amplitude modulation signal of the transmitter, and L4 is a choke to prevent high-frequency signals from passing through. Super regenerative oscillation circuit has self-checking function. The detected modulation signal generates a voltage drop on R4, which is sent to IC2 through R5 and C9 for amplification, shaping and re-amplification. This is accomplished by three inverters 13 and 12, 1 and 10,1and 2. The modulated signal after three-pole amplification has the same frequency as the transmitter (low frequency is 32.768KHz). X2 plays the role of frequency selection in the circuit, and signals with the same frequency can pass smoothly, thus avoiding the interference of many unnecessary external signals. The frequency-selective signal is sent to Q2 for amplification and shaping, and the amplitude of the signal is still very low. After the last two stages of open-circuit reverse amplification, the square wave signal with equal amplitude is output. R 1 1 current limiting, C 12 filtering, smoothing the square wave, delaying for tens of milliseconds, and eliminating the interference of external sharp pulses on the trigger circuit. K is the music selection switch, and the music signal is amplified by Q4 to push the speaker to make beautiful doorbell music. After the assembly principle is clear, the next step is the actual production. Of course, there will be some problems. If we just follow the drawings now, it will definitely not succeed, and debugging is also very important. Put away the prepared components and have a homemade printed circuit board. There are many ways to make the circuit board, and the requirements for the topic selection of the circuit board are not high in the self-made experiment. At this time, how to do the circuit board will not be introduced. You have to ensure the quality of components, just be superior. Weld IC 1 and its peripheral parts first, and do not weld X 1 and high-frequency parts. Now debug whether CD4069 is normal. Replace X 1 with a nonpolar capacitor of about1microfarad, temporarily replace X 1, and connect a red LED between the sixth pin of IC 1 and the ground. Turn on the power and the indicator light will flash, otherwise the 4069 will be broken. Solder this capacitor, switch back to the original X 1, remove the LED, and the rest can be soldered. Turn on the power again and test the current of the whole machine between 4.8 and 5.5 Ma, which is the most important index. If the range is greater than 0.5mA, you need to check whether there are other reasons. Secondly, measure the voltage values of B, E and C. When the circuit starts to vibrate, B is 5.5V-5.8V, E is 5.8V-6V and C is about 13V. The voltage at electrode B is several tenths of volts lower than that at electrode E, indicating that the circuit is normal. The collector voltage will exceed the power supply voltage, which is a characteristic of high frequency circuits. After the whole transmitting circuit is installed, it can be transmitted near an open short-wave (non-FM) radio, and the interference effect of the transmitting part on the radio can be clearly heard. So far, the installation and adjustment of the transmitter have been nearly completed. The receiver is equipped with a high-frequency receiving section Q3 and peripheral circuits R3, R4, R5, R6, C4, C5, C6, C7, C8, C9, L3, L4, etc. , and connected to a 3-volt power supply, measure the voltages of the three electrodes of b e c, which are 0.7V-0.8V, 0.2V, 1.3V- 1 respectively. L3 is wound three times, and the skeleton diameter is 5mm, 0.5 1 line, as explained earlier. If you don't have a suitable adjustable copper core, you can also fix this coil and replace C4 with an adjustable capacitor of 5-20P. An ammeter is connected in series with the emitter of Q3, and I = about I=0.35mA is measured. The working point at this level is basically normal. Then install X2 and all related resistors, capacitors and IC2 (Le film and Q4 are not installed), and connect a light-emitting diode in parallel at both ends of C 12. Be careful not to connect the wrong polarity. Short-circuit X2 with tweezers, and you can see that the LED is on, indicating that the back of the receiver is normal. The circuit welding of transmitting and receiving ends in one paragraph. The LEDs at both ends of C 12 should not be soldered for the time being, and then used later. Note: Before welding, if the circuit board is made, check whether the circuit design is correct before welding. All equipment, especially the manifold block, must be normal. The outer iron part of the soldering iron cannot be charged with static electricity, so it is better to be grounded safely to avoid damaging the equipment and causing trouble. The values of each part should be taken according to the requirements of the drawings, and the difference should not be too big. The working voltage and current of the above main parts are measured by digital 830 meter, and the values measured by different multimeters will be different. A small audio amplifier must be prepared before debugging is completed. Switch the audio input line into two lines in any way that does not damage the plug, one is the ground line and the other is the signal line, so that it can be soldered to the circuit board when debugging. Prepare soldering iron, solder the power amplifier input ground wire to the negative pole of the doorbell receiving board, connect the other signal wire with a capacitor of 103, and then weld it to the two pins of the receiving board IC2 4069. Turn on the power supply of the power amplifier and the receiving board, and adjust the volume key of the power amplifier, you can hear the loud noise from the speaker, which shows that the high-frequency connection part of the doorbell receiver you made is good. You can proceed to the next debugging. We have introduced how to verify that the transmitter is in normal transmission state. As long as the transmitter is assembled according to the parameters and can launch normally, it can be debugged with the receiving board. Hand-held transmitter (remote controller) is at the distance of receiving board 10cm~40cm, press the transmit key at any time and intermittently, carefully monitor the noise volume in the amplifier speaker, and adjust the copper core of L3 or the changed adjustable capacitor C4 with a non-inductive screwdriver, that is, adjust the receiving resonance frequency of the receiver to make it consistent with the signal frequency sent by the transmitter. Adjust it carefully and slowly (the copper core can be adjusted faster, and the capacitor must be adjusted slower). When it is adjusted to a certain position, the noise in the speaker can disappear or become extremely small or even unrecognizable. Then hold the hand of the transmitter away from the receiving board, 1 m or several meters, and press the transmitter to reduce the noise. At this point, the frequency has been adjusted to be close to the transmitter. Put the transmitter 3-5 meters away from the receiving board, let others press its key, and you can make fine adjustment. At this time, you should adjust it slowly (mainly to adjust the capacitance), and the receiver will not announce the adjustment until the noise in the speaker is the smallest than that in other positions. Weld the two input wires of the power amplifier firmly, press the transmit key, and see that the red LEDs at both ends of C 12 light up, and go out after a delay of several tens of milliseconds. The debugging method of the above receiver is a common method to make a network with infinite electrons, and it can also be said to be an exclusive method! You can learn from it.