Page 295 - FUNDAMENTALS OF COMPUTER

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NPP Number System, Boolean Algebra and Logic Circuits 295

A

B
Battery
Y
Bulb

Since the switches are in parallel, the My±{H$ pñdM g_mÝVa _| bJo h¢, Bg{bE {H$gr EH$
current will flow in the bulb when any of the pñdM Ho$ ON hmoZo na ~ë~ ON hmo OmEJmŸ& AV… h_ H$h
switches is ON. Therefore we can say that Y =
1, When A or B or both are 1. Y = 0 only when gH$Vo h¢ {H$ `m Vmo A `m B `m XmoZm| Ho$ 1 hmoZo na Y
A and B both are Zero. Therefore the circuit = 1 hmoJmŸ& Y=0 V^r hmoJm O~ gmao pñdM Iwbo hmo `m A
follows the truth table of OR gate. By increasing = B = 0 hmoŸ& AV… `h OR JoQ> H$s gË` Vm{bH$m H$m
No. of switches in parallel we can draw the nmbZ H$aVm h¡Ÿ& pñdMm| H$s g§»`m ~‹T>mH$a h_ Xmo go
circuit for OR gates containing more than two A{YH$ BZnwQ>m| dmbm OR JoQ> ^r ~Zm gH$Vo h¢Ÿ& O¡go 3-
inputs. The circuit for 3-input OR gate can be
drawn as: BZnwQ> OR JoQ> H$m n[anW Bg àH$ma hmoJm …
A
B
C

Battery
Y

Bulb

The bulb may glow when A or B or C or A `m B `m C VrZm| _| go EH$ ^r {ñdM Mmcy hmoJm
any two or three switches are ON. Vmo ~ë~ Mmcy hmo OmEJmŸ&

OR Gate using Diodes S>m`moS> H$s ghm`Vm go OR JoQ> ~ZmZm
Consider the following circuit containing {ZåZ{b{IV n[anW H$mo XoImo, {Og_| Xmo S>m`moS> Am¡a
diodes and a load resistor : EH$ bmoS> à{VamoY H$m Cn`moJ {H$`m J`m h¡…

D 1
A

D
2
B Y
R
L