Electronic Circuit ding-dong Sound for any Alarm
Basically the circuit alternates between two frequencies which are adjustable. This produces the “ding-dong” sound.

electronic circuit ding-dong sound for any alarm
Published 14/03/2010 & Filed in ELECTRONIC CIRCUIT. Part 2
Tags: alarm, Alarmanlage, alarme, Circuit, ding-dong, Electronic, NE555, NE555、, NE555,, sonore, sound, अलार्म, इलेक्ट्रॉनिक, झंकार, ध्वनि, アラーム、, サウンド, チーンチーン、, 丁洞,, 声音, 报警,, 电子,, 电路,, 電子、