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”.
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THE LIGHT IN THE SWITCH
Not to look for the switch in the dark, to make it a backlit "Neonka" from the starter of the fluorescent lights and the resistor 100 ohms, connected in series— that's the whole scheme....
VILA COMBINE
There is near Moscow, Serpukhov district, well-known vegetable farm "zaoksky". Here, in high school, already DEA works student design bureaus, organized from the students of high schools...
