The Flashmatic (US, Zenith Electronics, 1955) looked like a toy ray gun and worked by tripping a sensor in the corner of the screen
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The Zenith Space Command used ultrasound - tiny hammers generated a frequency when they hit aluminium bars inside the remote
![… The frequencies used in remotes like the Space Command were too high for the human ear to pick up, though they could be discernible to animals such as dogs and cats. (I can remember my older brother and sister chasing my grandparents’ cats around the house with just such a device.)]()
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