2B-AUTOMATIC ELECTRONIC CANDLE
The electronic age is otherwise called as age of magic because the projects designed and developed appears like a magic to the people. The bulb used in the project glows as soon as there is darkness. When light comes, the bulb reduces its light to the extend of a candle. It helps you to trace match
box etc in the dark.
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 the project mainly depends on IC 555 and LDR. The resistance of the LDR increases or becomes high in the dark and in the presence of light it becomes low. Here the IC 555 is employed as a timer and pin no 2 of the IC is grounded through a LDR and preset. The bulb does not glow as the collector voltage of the transistor 2N3055 remains high during the low state of pin 3 of the IC. But as soon as the light stops falling on LDR , the trigger pin no. 2 of the IC 555 assumes low state and as a result the information at pin no 3 becomes high resulting voltage drop at the collector of the transistor. The bulb does not glow when the collector voltage drops.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
*Keep LDR in such place so that the light falls directly on LDR.
*While mounting transistor, you should connect collector , base & emitter properly.
*Please use resistance of the exact value as given in the circuit.
*Use IC base for mounting of IC 555.
*First of all check all the components as per circuit.
2N 3055 = 1
IC555 = 1
LDR = 1
100K = 1
68K = 1
560E = 1
BULB 9V = 1