Question

A diode detector is used to detect an amplitude modulated wave of 60% modulation using a condenser of capacity 250pF in parallel with load resistor of resistance 100 Kilo ohm. find the maximum modulated frequency which could be detected by it....

Answer 1

do u know the basics of amplitude modulation!?

Answer 2

@Mashy pls help!!!!

Answer 3

ya...smwt!

Answer 4

carrier wave superimposed on signal...and all that......but dunno prperly...

Answer 5

@Niranjana_Prasad carry on please

Answer 6

carry on what? all i can say is that we dont know enough to solve that question.. just the devices used for modulation and the algebraic proof..
@AnthonyStark that good enough?

Answer 7

ohk! @Mashy ,,,,,,,u know wats our condition here

Answer 8

^^^^pic

Answer 9

ok.. using the charging and discharge time equation u can find out how much MIN. time the wave should give the rc circuit to get detected..

do you know the charging and discharging equation?
p.s. this is what i think ok :P.. i am not really sure..

Answer 10

so that min time, is the min time period.. or if you do the reciprocal, the maximum frequency.. dunno how the modulation index plays a role..

Answer 11

hey.... i have the solution....but i cant understand it ....

Answer 12

that document is the solution?!

Answer 13

no....that was part of the solution,,,,wait a sec...

Answer 14

are u sure? that looks like a filter.. to me!

Answer 15

oh wait thats how it is!

Answer 16

yea thats about right, an RC filter should do the job of envelop detection!.. so the input signal falls, the capacitor discharges slowly.. and thats how the signal is held high..
what i said isn't totally right then :P

Answer 17

ah.. dang.. ll just wait for your solution :P

Answer 18

http://www.resonance.ac.in/jee-main-2013-answer-key-solutions/jee-main-paper-1-solutions-2013-english-1.1.pdf

Answer 19

qn 12

Answer 20

ok..this is ALL i know,,,and nothing more,,,: the P-N junction over there serves as a rectifier,,,so now u have the rectified modulated signal,,,,,,and i think the rest of the circuit plays the role of ENVELOPE DETECTOR,,,,,,,,,sadly we know only the TERMS (hi fi ),,like envelope detector and all,,,,,but they havent taught us the working!!!

Answer 21

i only want to know HOW the rest of the circuit works as a envelope detector,,,,and how to derive that dumb formula which they SIMPLY used

Answer 22

the envelop detector works pretty much like a filter man..

see.. to detect the envelop, what we need is, the incoming modulated signal as it hits its max, we need to HOLD that level.. do u get that point??