Happy Birthday To You Electronic Candle: Traditional Chinese Circuit D

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"Happy Birthday to You" Electronic CandleBirthdays are happy, and the atmosphere of birthdays is joyful and lively. If you can automatically offer a few words of congratulations and a song to wish you a happy birthday as the candles are lit on the children's birthdays, it will be even better.The "Happy Birthday to You" electronic candle is designed for just that. When everyone sits in front of the birthday cake and lights the candles, it will say two sentences in English "Happy birth day to you" in succession, and then a piece of music "Happy birthday to you" will play. The congratulations and songs will be repeated repeatedly until the candles are blown out. "Happy Birthday to You" electronic candle is undoubtedly a very popular birthday gift for children.1. Circuit working principleThe circuit principle of the "Happy Birthday to You" electronic candle is shown in Figure 27-1. It is composed of light control switch circuit, timing conversion circuit, language, music circuit and audio circuit.Figure 27-1In the figure, the phototransistor BG1 and the one-way thyristor scR are light-controlled switching circuits. When there is no light, the dark resistance of BG1 is very large, the control electrode of the thyristor scR is turned off due to no triggering, and the power supply of the rear circuit is blocked; when the light of the candle shines on BG1, the dark resistance decreases sharply, and the divided voltage on the resistor R2 triggers the 3CR to turn on, turning on the power supply of the rear circuit.Time base integrated circuits IC1, IC2 and surrounding components form a timing conversion circuit. The moment the power is turned on, the power charges the capacitor C5 through W2, causing the potential of the input pin ② of IC2 to be lower than 1/3 of the power supply voltage. Therefore, IC2 is triggered first to start timing work. The ③ pin of IC2 outputs a high level, and the relay J2 operates, and the normally open contact Point J2-1 is closed, triggering the language integrated circuit IC3, and sending out two English congratulations through the audio circuit. For about 5 to 6 seconds (that is, the two English congratulations have just been finished), the IC2 delay time ends, the ③ pin becomes low level, J2 is released, and the congratulations stop. The signal at pin ③ drops and forms a negative sharp pulse along the differential circuit composed of resistor R1 and capacitor C6 and enters the input terminal ② of IC1, triggering IC1. Its output terminal ③ is high level, IC1 starts to work regularly, relay J1 acts, and the normally open contact J1-1 closes, triggering the music integrated circuit IC4 plays the music "Happy Birthday to You" through the audio circuit for about 12 to 15 seconds. IC1's timing ends, J1 is released, and the music stops. At the same time, IC2 is triggered to make it work again on schedule, and the cycle is repeated in sequence until the candle goes out and the language and music stop.Since the reset pins of the time base integrated circuits IC1 and IC2 are both grounded, malfunction will not occur when the power is turned on. The timing conversion control circuit is a sequencer. IC2 and IC1 work sequentially according to the set time. Only after the current controller completes its work, can the next controller automatically start to work. The working time of each controller can be set independently without mutual interference.2. Component selectionIC1 and IC2 are time base integrated circuits, which can be time base circuits such as NE555 or 5G1555.IC3 is a language integrated circuit, which uses CIC5607 language integrated circuit and stores "Happy birthday to you" in English.IC4 is a music integrated circuit, using CW9310, which contains the music "Happy Birthday to You".J1 and J2 are 6V DC relays, and 4100 type micro relays can be used, which are small in size and low in price.BG1 is a photosensitive transistor, and 3DU5 is selected.BG2 is an NPN transistor, choose 3DG6 or 9012.BG3 is a PNP transistor, choose 3AX81 or 9013.Y is a thin, small-diameter speaker, 0.25W, 8Ω.In order to reduce the size, the battery is a 6V laminated battery. …

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