Anti-lost Reminder For Children: Traditional Chinese Circuit Design Gu
In short: Traditional Chinese Practical Anti-lost reminder. This entry documents a circuit & prototype taken from Chinese practical-technology literature, written for small-scale makers and home producers. The text below is the full English translation of the original Chinese workshop notes, covering materials and quantities, the step-by-step sequence, and the practical cautions recorded in the source. Roughly 1875 words of English technical text, translated and preserved without editing. It is intended for experimental and reference use, not for regulated or commercial certification.
Children's anti-lost reminderWhen you take your children out to play, you may be most worried about the child getting lost. This device can effectively solve this problem. The device consists of a transmitter and a receiver. The transmitter is put into the child's pocket, and the receiver is held by an adult. When the child is more than 3m (meters) away from the adult, the receiver will sound an alarm to remind the adult to pay attention and prevent the child from getting lost. alt="304.jpg (38642 bytes)">Figure 217-1Figure 217-1 is the transmitter circuit diagram. It consists of IC time base integrated circuit NE555, R1, R2, C1. The 1KHz low-frequency oscillator modulates the high-frequency oscillator composed of the triode VT and peripheral components. The modulated high-frequency signal is emitted from C7 to the internal micro-antenna into space. C8 is used to widen the frequency band and prevent the influence of human body induction on the frequency. Actual use has proved that this component is indispensable. Figure 217-2 is the receiver circuit diagram. When the receiver receives the signal from the transmitter, the ② pin of the integrated circuit TDA7000 outputs a low level, the music integrated circuit CW9300 does not work without a high-level trigger signal, and the speaker BL is silent. When the distance between a child and an adult exceeds 3m, the receiver cannot receive the signal from the transmitter, and the ② pin output of TDA7000 becomes high level, and the CW9300 is triggered to work, and an alarm sounds from BL to remind the adult that the child has gone far. …
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Lei Cheng
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Lei Cheng