The chime is for use in situations where there is bell or chime at the front door as well as at the back door. When loud bells or chimes are used, it may be difficult to determine which one is being rung. This Selective Door Chime Circuit will solve this problem which can produce two or three different sounds. When two of these circuits are built, the one at the front door is set to produce, say, two tones, and the one at the rear door, three tones.
Learn how to make your own a very simple diy homemade door alarm Alarm. It uses CPU battery holder/jacket with its cell, a 5 volts buzzer & 2 pieces of gem clips. This device is designed by me which is stand alone. This can be placed on doors or windows to alert someone, if they […]