Traditional Chinese Practical device: Circuit Design, Parts List & Workshop Prototype Guide
In short: Traditional Chinese Practical device. 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 1808 words of English technical text, translated and preserved without editing. It is intended for experimental and reference use, not for regulated or commercial certification.
A device for listening to the "music" of the grassHave you ever "heard" the most exciting moments in your life? For example, have you ever heard the sound of growing grass while sitting near the grass? This can be achieved with the small device "Grass Tuner" introduced below.In effect, you are injecting music into two points on the lawn and using an amplifier to pick up the sound at two other points in the field. As shown in Figure 25(a) and (b), the sound is sent into the earth through two metal rods inserted into the ground. Any metal rod can be used (for example, copper-plated rod is better). There should be some distance between the metal poles.The power output of the stereo amplifier drives audio current into the grass. To protect the stereo amplifier, a buffer amplifier LM386 is used. The audio signal is sent to the "signal in" end in the figure. The buffer amplifier is powered by a 9V battery. The soil between the two metal poles acts like a voltage divider.To recover the signal you sent into the ground, use an amplifying integrated circuit such as the Model 741 shown in the figure. The headphones are mono. Be careful when using headphones, as loud sounds can damage your hearing. Start by turning the volume down and holding the headphones further away from your ears. After making sure that the volume is tolerable, adjust the volume to an appropriate level and adjust the position of the headphones appropriately.The 741 circuit picks up the audio signal in the grass through the pick-up rod. These pickup rods can also be copper-clad rods. The conductivity of the soil varies, and the position of the pick-up rod needs to be adjusted to obtain the best volume; generally, the further away the pick-up rod is, the louder the volume picked up. alt="25a.jpg (10128 bytes)">Figure 25(a) …
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Lei Cheng
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