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Simple door bell for access control systems
This is very simple electronic doorbell circuit which is specifically design to interface with commonly available access control systems. This circuit is designed around NE555 timer IC and LM386 audio power amplifier IC. Because most of the access control systems use 12V power supplies this doorbell is also design to work with 9V to 15V DC power source.
Final view of our doorbell project prototype.
We test this doorbell with several YOUHE access control systems and it works well with all the tested models.
In this design NE555 is setup to obtain 840Hz – 860Hz output with above 80% duty cycle. To get more effective output we use small 3.5 inch, 8Ω tweeter with our prototype design.