The prospect of optically controlled switches

The optically controlled switch was adopted 20 years ago. 1995 I made a light-controlled protection circuit with a photosensitive battery and an amplifier circuit, which is not a new invention. Optically controlled switches have only been known to the public in recent years. Its function is regarded as a special purpose. The most commonly used are advertising lights, external lighting and the control of some special equipment, which are useful, but not suitable for widespread use and have no prospect.