Exposure Meter, also known as the light meter. A meter that measures the intensity of light during photography and controls the exposure time and aperture size of the photograph. A device used in photography to determine the correct camera lens and shutter settings. There are two basic exposure meters: one for the battery and one for the other. Most exposure meters measure reflected light (light reflected from the object to the camera); some exposure meters measure the incident light, the light actually projected onto the object; others can measure both types of light. The flash meter measures the output of the electronic flash. Some photographers use handheld watches, but camera built-in watches are more common. Many built-in watches are mounted behind the lens. In an automatic camera, the built-in watch sets the lens aperture, flash speed, or both. In a non-automatic camera, the photographer himself reads the watch as a reference for manual setting. Alarm release mainly uses standard equipment such as audio alarms. During wartime, communication, broadcasting, and television systems must prioritize the transmission and issuance of air defense alarm signals, and auxiliary means such as sirens, horns, and gongs can also be used. The sound alarm must be set at the designated location, and the alarm facilities must be maintained in good working condition. The release and transmission of alarms should be fast and accurate, and multiple means should be used simultaneously; Strengthen communication and liaison with superiors, subordinates, and neighbors, receive air raid intelligence information at any time, strengthen observation of air targets, and promptly report air raid intelligence; According to the situation and duration of the air raid, timely release the warning signal. With the sudden increase of air raids, the increase of attack methods, and the expansion of destruction, the importance of air defense alerts is increasingly being valued. The accuracy, timeliness, and continuous issuance ability of air defense alerts are required to be higher. The issuance methods of air defense alerts will also become more flexible and diverse with the construction and improvement of communication and network. Early Warning System, Control Devices, Electronic Sirens, Natural Disaster Warning System, Alarm System Taixing Minsheng Electronic Co.,Ltd. , https://www.ms-speakers.com