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RING BELL ELECTRONIC CIRCUIT USING NE555 DIAGRAM This circuit produces oscillating frequency around 1kHz, and able to be converted by changing the value of resistor R1. The speaker will produce a long beep sound with 1kHz frequency. Here is the schematic : Parts list :     Resistor R1 : 10k ohm     Resistor R2 : 56k ohm     Capacitor C1-C2 : 0.01 uF     Polar capacitor C3 : 1 uF/15V     IC timer : NE 555     Speaker : 8 ohm 0.5 W     ON/OFF switch     5-15V Power supply

Sometimes ringing the bell manually becomes difficult, especially when you are holding something in your hands. The sound-operated music bell takes care of the problem .In this circuit, the use of an external relay has been eliminated. The circuit comprises a trigger stage (around BC548B), a timer stage (NE555) and a melody stage (around UM66 and SL100). Transistor BC548B is biased inn class C operation. Every second sound cause triggering at pin 2 of 555 timer IC.                                                                                When VR1 is at maximum, the hold-on time of NE555 is around 3...

Call Bell with Welcome Indication Circuit Diagram. Here is a simple call bell circuit that displays a welcome message when somebody presses the call bell switch momentarily. the alphanumeric display can be fitted near the call bell switch. the circuit is built around two 555 ICs (IC1 and IC2), seven KLA511 common-anode alphanumeric displays (DIS1 through DIS7) and a few discrete components. For easy understanding,  the entire circuit can be divided into  two sections: controller and display. the controller section is built around  IC1 and IC2, while the display section is built around alphanumeric displays (DIS1 through DIS7).  As shown in the circuit, both IC1 and IC2 are wired as monostable  multivibrators having time periods of around 5 seconds and 2 minutes, respectively. You can change the time period of IC1 by changing the values of resistor R12 and capacitor  C3. Similarly, the time period of IC2  can be changed by changing the values of resisto...