Old alarm clocks and many doorbells and telephones emit a signal due to the blows of “hammer” metal hemisphere of the bell.
If you are annoying it’s pretty sharp rattling, stick a bell in place of hitting it square of adhesive tape or medical adhesive tape device will beep “whisper”.
.
Recommend to read
FLYING UNDER THE ROOF
For many school model aircraft clubs create room flying models is the only available form of modeling. Judge for yourself: the season of the competition model, as a rule, coincides with...
HYDRO CART “MUSTANG”
It was named a hydrocart, although it looks more like a kind of water motorcycle. This sports micro-vessel was built at the Donetsk Regional Young Technicians’ Station in the “Small...