2B-CALL BELL GUEST COUNTER
——————— This project may replace the future musical bell as many facilities are available with this. It indicates Please WAIT/DO NOT WAIT to the outsider as well as counts the number of guests visited during your absence.
TECHNICAL DESCRIPTION AND WORKING
This project has been developed and successfully Tested O.K. by TV Engineer Technical Lab.
Now a days, the musical calling bells are most popular on the market. But this project has certain specialities. It can easily count as many as 99 guest. The project the guest whether to wait or not to wait in. It counts the number of guests visited during your absence. If you are not at home, the guest gets the information DO NOT WAIT and does not push to the bell ON unnecessarily. If you do not want to enter any guest, you can use DO NOT WAIT position in emergency. We neighbours are also disturbed by frequent bell sound. Similarly in your absence the guests donot wait for long if they get the information NOT WAIT.
The project employs IC 555. The IC 555 is a propular IC and can be used as digital as well as analog. The IC 4033 has been used in two places which provides the END necessary biasing. The project works in two modes. In the first mode i.e. when the switch is on a position, be on B position ,if work as DO NOT WAIT and the counter will start working. When the guest pushes/presses the bell switch,the out put becomes available at pin No 3 and indicates IN or OUT depend if on the position of the switch.
PRECAUTIONS WHILE ASSEMBLING
1.Use IC base instead of soldering IC directly.
2.Clean the PCB before and after soldering in order to avoid short circuit.
3.Check all the components as per circuit specifications.
4.Use only the common cathode of FND segments.
LIST OF COMPONENTS
Type from & OK EP Vol II page 5