Digital Electronics - Flip-Flops - Discussion
Discussion Forum : Flip-Flops - General Questions (Q.No. 20)
20.
A 555 operating as a monostable multivibrator has an R1 of 1 M
. Determine C1 for a pulse width of 2 s.
. Determine C1 for a pulse width of 2 s.1.8 
F
F18 F
18 pF
18 nF
Discussion:
9 comments Page 1 of 1.
KIRAN V said:
5 years ago
For Mono-stable multi-vibrator using 555 timer circuit output pulse width "tp = 1.1 *R * C".
Given: tp = 2 s; R = 1 M ohms.
C = tp/(1.1 *R).
C = 2/(1.1 * (1 * 10^6) ) ==> 1.8181 Micro Farad.
Given: tp = 2 s; R = 1 M ohms.
C = tp/(1.1 *R).
C = 2/(1.1 * (1 * 10^6) ) ==> 1.8181 Micro Farad.
(1)
Siva said:
6 years ago
From formula, W = 1.1RC.
Here W = 2s R = 1M ohms.
2 = 1.1*1*10^6*C.
C = 2/(1.1*1*10^6) = 1.818 * 10^-6.
= 1.8 Micro Farad.
Here W = 2s R = 1M ohms.
2 = 1.1*1*10^6*C.
C = 2/(1.1*1*10^6) = 1.818 * 10^-6.
= 1.8 Micro Farad.
NASEER said:
1 decade ago
For exact formula T = 1.14 RC.
Ruksana said:
1 decade ago
For mono stable multivibrator using 555 timer circuit output pulse width T = 1.1RC.
So 1.8 micro farad is the right answer.
So 1.8 micro farad is the right answer.
Hiren said:
1 decade ago
Muskan is wrong here.
If you do calculation answer is not what muskan gives.
Pratusha's answer is right .
If you do calculation answer is not what muskan gives.
Pratusha's answer is right .
Meghna said:
1 decade ago
Can you please tell me what is W here and how it is calculated?
Muskaan said:
1 decade ago
Actually
RC = (1 / 2*pi*f)
or , f = (1 / 2*pi*RC)..........(1)
The pulse width (tp) of an ideal square wave is equal to half the time period. The relation between pulse width and frequency is then given by,
f = (1 / 2*tp)..................(2)
Equating 1 and 2 ->
tp = pi*RC
or,
C = tp / (pi*R)
C = 1.75 * (10^-6)
RC = (1 / 2*pi*f)
or , f = (1 / 2*pi*RC)..........(1)
The pulse width (tp) of an ideal square wave is equal to half the time period. The relation between pulse width and frequency is then given by,
f = (1 / 2*tp)..................(2)
Equating 1 and 2 ->
tp = pi*RC
or,
C = tp / (pi*R)
C = 1.75 * (10^-6)
Saurav suman said:
1 decade ago
@Pratyusha. Please can you tell me from where you got this formula.
Because as far I no.
Time constant t =5 rc.
Because as far I no.
Time constant t =5 rc.
Pratyusha said:
1 decade ago
From formula, W = 1.1RC.
Here W = 2s R = 1M ohms.
2 = 1.1*1*10^6*C
C = 2/(1.1*1*10^6) =1.818 *10^-6
= 1.8 Micro Farad
Here W = 2s R = 1M ohms.
2 = 1.1*1*10^6*C
C = 2/(1.1*1*10^6) =1.818 *10^-6
= 1.8 Micro Farad
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