An automatic table tennis ball server is designed by using infra-red sensor and a few electric devices.

利用红外光传感器和较少的电子器件，设计了一种乒乓球全自动供球器。

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An automatic table tennis ball server is designed by using infra-red sensor and a few electric devices.

利用红外光传感器和较少的电子器件，设计了一种乒乓球全自动供球器。

youdao