User manual

page 25
Analog System Lab Kit PRO
2.1.3 Monostable Multivibrator (Timer)
Figure 2.4: Astable Multivibrator and its characteristics
Figure 2.6: Monostable Multivibrator and its outputs
- -
V
bV
= =
1
1
1
1
1
2
2
1
1
1
1
1,5
4
ln
ln
ln
V A
V
V
A
A
R R
R
A
A
A
V
V
V
V
V
T RC
RC
t
RC
V
R R
R
R
R
R
f
T
kHz
ms
RC
1
1
1
1 2
1
0
1 2
1
1
i
i
ss
ss
ss
ss
ss
0 0 0
0
0
0
0
0
2
$
$
$
$
$
$
$
$
$
$ $
$
$
!
1
b
b
b
b
b
b
b
b
b
b
b
b
b
x
&
=
=
=
+
=
+
=
+
=
+
=
=
x
x
x
=-
-
+
-
-
-
+
_
d
d
d
i
n
n
n
- -
V
bV
= =
1
1
1
1
1
2
2
1
1
1
1
1,5
4
ln
ln
ln
V A
V
V
A
A
R R
R
A
A
A
V
V
V
V
V
T RC
RC
t
RC
V
R R
R
R
R
R
f
T
kHz
ms
RC
1
1
1
1 2
1
0
1 2
1
1
i
i
ss
ss
ss
ss
ss
0 0 0
0
0
0
0
0
2
$
$
$
$
$
$
$
$
$
$ $
$
$
!
1
b
b
b
b
b
b
b
b
b
b
b
b
b
x
&
=
=
=
+
=
+
=
+
=
+
=
=
x
x
x
=-
-
+
-
-
-
+
_
d
d
d
i
n
n
n
(2.5)
The circuit diagram for a monostable multivibrator is shown in 2.6. The trigger
waveform shown in Figure 2.5 is applied to the monostable. The negative edge
triggers the monostable, which produces the square waveform shown in Figure 2.6.
R2
R1
VC
R
V
O
C
+VSS
-VSS
The monostable remains in the “on” state until it is triggered; at this time, the circuit
switches to the “o” state for a period equal to
--
V
bV
==
1
1
1
1
1
2
2
1
1
1
1
1,5
4
ln
ln
ln
VA
V
V
A
A
RR
R
A
A
A
V
V
V
V
V
TRC
RC
t
RC
V
RR
R
R
R
R
f
T
kHz
ms
RC
1
1
1
12
1
0
12
1
1
i
i
ss
ss
ss
ss
ss
00 0
0
0
0
0
0
2
$
$
$
$
$
$
$
$
$
$$
$
$
!
1
b
b
b
b
b
b
b
b
b
b
b
b
b
x
&
=
=
=
+
=
+
=
+
=
+
=
=
x
x
x
=-
-
+
-
-
-
+
_
d
d
d
i
n
n
n
. The equation for
--
V
bV
==
1
1
1
1
1
2
2
1
1
1
1
1,5
4
ln
ln
ln
VA
V
V
A
A
RR
R
A
A
A
V
V
V
V
V
TRC
RC
t
RC
V
RR
R
R
R
R
f
T
kHz
ms
RC
1
1
1
12
1
0
12
1
1
i
i
ss
ss
ss
ss
ss
00 0
0
0
0
0
0
2
$
$
$
$
$
$
$
$
$
$$
$
$
!
1
b
b
b
b
b
b
b
b
b
b
b
b
b
x
&
=
=
=
+
=
+
=
+
=
+
=
=
x
x
x
=-
-
+
-
-
-
+
_
d
d
d
i
n
n
n
is shown
below.
After triggering the monostable at time t, the next trigger pulse must be applied
after
--
V
bV
==
1
1
1
1
1
2
2
1
1
1
1
1,5
4
ln
ln
ln
VA
V
V
A
A
RR
R
A
A
A
V
V
V
V
V
TRC
RC
t
RC
V
RR
R
R
R
R
f
T
kHz
ms
RC
1
1
1
12
1
0
12
1
1
i
i
ss
ss
ss
ss
ss
00 0
0
0
0
0
0
2
$
$
$
$
$
$
$
$
$
$$
$
$
!
1
b
b
b
b
b
b
b
b
b
b
b
b
b
x
&
=
=
=
+
=
+
=
+
=
+
=
=
x
x
x
=-
-
+
-
-
-
+
_
d
d
d
i
n
n
n
. The formula for
--
V
bV
==
1
1
1
1
1
2
2
1
1
1
1
1,5
4
ln
ln
ln
VA
V
V
A
A
RR
R
A
A
A
V
V
V
V
V
TRC
RC
t
RC
V
RR
R
R
R
R
f
T
kHz
ms
RC
1
1
1
12
1
0
12
1
1
i
i
ss
ss
ss
ss
ss
00 0
0
0
0
0
0
2
$
$
$
$
$
$
$
$
$
$$
$
$
!
1
b
b
b
b
b
b
b
b
b
b
b
b
b
x
&
=
=
=
+
=
+
=
+
=
+
=
=
x
x
x
=-
-
+
-
-
-
+
_
d
d
d
i
n
n
n
is given below.
Table 2.1: Plot of Hysteresis w.r.t. Regenerative Feedback
S. No. Regenerative Feedback Hysteresis
1
2
3
4
R
R
VC
R
C
C
Trigger V
D
+VSS
-VSS
experiment 2
Figure 2.5: Trigger waveform