It is an important tool for communication and distress in emergency situations. It can transmit information through radio waves to help people stay in touch and get help when traditional communication networks fail. It plays an irreplaceable role in ensuring the safety of people's lives and property. It can not only provide timely communication support in emergency situations, but also help rescuers quickly locate the location of distress and improve rescue efficiency.

It is an electronic measuring instrument used to measure electrical quantities such as voltage, current and resistance. Widely used in electronic technology and other related fields, it is an important tool to detect circuit problems and confirm the status of components. There are many types, including analog and digital, digital multimeters are more common because of more accurate readings and easier operation. There are usually multiple measurement gears, and the user can choose to measure voltage, current or resistance as needed. It is indispensable in the laboratory and industrial fields, and is also extremely popular among home repair and electronics enthusiasts. It is a commonly used tool in electronic engineering and physics teaching.

It is an electronic device that can provide a stable DC voltage, and the output voltage can be maintained at a predetermined value regardless of changes in the input voltage or load current. It is widely used in equipment requiring stable voltage. It is usually composed of an ordinary power supply and a voltage regulation device, and its output voltage is not affected by changes in AC input voltage or load current. Compared with non-regulated power supplies, regulated power supplies can provide a more stable voltage, reducing output voltage changes caused by input voltage fluctuations or load changes, thereby protecting sensitive electronic components from damage.

The Geiger M ü ller counter, also known as the Geiger counter, is a counting instrument specifically designed to detect the intensity of ionizing radiation (alpha particles, beta particles, gamma rays, and X-rays). Using an inflatable tube or chamber as a probe, when the voltage applied to the probe reaches a certain range, each pair of ions produced by ionization of the radiation inside the tube can amplify and generate an electric pulse of the same size, which is recorded by the connected electronic device, and thus measure the number of rays per unit time.