You can use bulbs or L.E.Ds on this project for any kind of display. The other speciality of this project is that it uses different colours L.E.Ds or bulbs to give visual information, resulting more attractive display.
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.
This project employs timer IC555, IC7493 and IC4099. The timer IC555 is a most popular integrated circuit and its output/input can be connected to any TTL or CMOS circuit. In this project, the IC555 is employed as a multivibrator and its output is connected to the trigger pin no. 14 of IC7493. Four binary informations are available from the output of IC7493, which are applied to the input of 3 bit addressable IC4099. The input pin of IC4099 are 5, 6, 7 and data pin no. 2 and output pins are 9, 10, 11, 12, 13, 14 and 1. The output of this IC depends on information available to data at pin no. 2. In normal condition this IC does not function as the information on data pin is very low. When the information becomes high at its data pin, binary information are released. These binary information conduct the transistors seperately. The transistors are connected to the L.E.Ds or bulbs, through the relay. The special feature of this project is that when information at data pin is low, the bulbs or L.E.Ds will glow diminishing while these will go on glowing in the presence of high information at the data pin.
PRECAUTIONS WHILE ASSEMBLING THE PROJECT:-
*For 5 Volt supply use regulator IC 7805.
*Check polarity of electrolytic capacitor while mounting on PCB otherwise reverse connection may damage it.
*Use IC base for mounting of the ICs otherwise IC may damage due to current leakage of soldering iron.
*First of all check all the components as per circuit.
*While mounting transistor, you should connect collector , base & emitter properly.
*Please use resistance of the exact value as given in the circuit.
IC 555 = 1
IC 7499 = 1
IC 4099 = 1
100MFD/25V = 1
BC148 = 8
1K = 8
4.7K = 1
1K = 8