2B-IN/OUT INDICATOR WITH MUSICAL BELL
Now-a-days calling bells are used in each and every house to indicate the visit of visitors. If a visitor comes in your absence , the bell rings but after some time he has to wait for sometime. This project which is very simple and cheap can solve this problem. The visitor can get the information whether you are IN or OUT. This project will inform about your presence as well as entertain him with a pleasent musical tune. The doctors and officers can use it of their Office call bell.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and tested O.K. in our TV Engineers Technical Lab. The components and PCB used in the projects published in our books are available for sale at resonable price.
The working of this project is very simple. The L.E.Ds are fitted on line plate or hard board in such a way that IN or OUT is indicated when these glow. To produce musical tune, one IC UM66 and one transistor BC158 are employed. When you are not at home and one visitor pushes the bell switch, the anodes of L.E.Ds used to indicate ‘OUT’ starts receiving positive supply and as a result all the diodes become forward biased. The L.E.Ds glow and indicate OUT. Under this condition the bell does not ring as the related circuit is in OFF condition. When you are at home and the visitor pushes the Bell switch, the IN indicating L.E.Ds glow because of forward bias and along with this, the biasing of the IC UM 66 becomes complete . As a result the bell rings and indicates the coming of a visitor.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
*Check primary and secondary winding of the step-down transformer before connecting it.
*While mounting transistor, you should connect collector , base & emitter properly.
*First of all check all the components as per circuit.
*Check +ve & -ve terminal of L.E.D. while mounting on PCB.
*Check polarity of diode and capacitor while assembling.
IC UM 66 = 1
IN 4007 = 4
ZENER 3.1 V= 1
0-6 STEP DOWN TRANSFORMOR[500MA] = 1
1000MFD/25V = 1
100MFD/25V = 1
BC148 = 1
BEL 187 = 1
BC 158 = 1
100E = 2
560E = 1
4K7 = 1
10K = 1
PUSH TO ON SWITCH = 1
DOUBLE POLE TWO WAY SWITCH = 1
GREEN L.E.DS = 21
RED L.E.DS = 13