Abstract: An additional active safety switch for gas burner with active restoring capability is provided to actively prevent the ignition trigger of the gas burner from being pulled arbitrarily or from keeping enabled constantly for enhancement of security.

Abstract: A stethoscope with an indexing detent comprises a hollow body, a rotary tubular shaft, a and an indexing detent. The hollow body comprises two different microphones and a plurality of openings with the same diameters as that of the microphones. The rotary tubular shaft can be rotated around the hollow body, and it further comprises an axial hole whose central axis is aligned with that of the rotary tubular shaft, and a plurality of circular through holes at the locations related to the openings. On one of the circular through holes, there is a lock ball. Inside the rotary tubular shaft, there exist a resilient element which pushes the lock ball outward. When the circular through holes are directly aligned with the openings, the lock ball is pushed outward by the compressible resilient element and then partially goes into one opening to lock the related locations of the rotary tubular shaft and the hollow body.