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NAME:-DHANIRAJ R. YADAVCLASS:-T.Y.B.SC . DIV.:- ’A’
ROLL NO.: 29 SEAT NO.: 13-16032
Topic name:-Bistable Multivibrator Circuit’s Information
Department :- Physics
BISTABLE MULTIVIBRATOR
O OTHER NAMEO THE COMPONENT VALUESO HOW TO MADE CIRCUITO WHAT IS THE PRINCIPLE O APPLICATION & SUMMARYO REFERENCES
OTHER NAME
O BISTABLE MULTIVIBRATOR IS ALSO CALLED AS FLIP FLOP.
O AS THE NAME INDICATES,THE BISTABLE MULTIVIBRATOR HAS TWO STABLE STATES. THAT WHY CALLED BISTABLE MV.
HOW TO MADE CIRCUIT
CIRCUIT OPERATIONO Bistable multivibrator, or a flip-flop, You will notice that it
has two outputs and two inputs.O The outputs are labeled Q and Q(NOT). The inputs are
marked SET and RESET. The set and reset can be used to either preset
O the circuit or to use it as a memory storage device. If the trigger applied to the multivibrator causes the output (Q) to go high,
O the circuit is set. A set circuit is the equivalent of a closed toggle switch. If the trigger applied to the multivibrator causes the
O output (Q) to go low, the circuit is reset. When the circuit is in a reset condition, it is the equivalent of an open toggle switch.
CF351 F05 - 6
Q1 on
Circuits & Components.
2 Stable States; Q1 On, Q2 C/OOr Q2 On, Q1 C/OFrequency Out is
½ the Input.
C3 .001f
C4 .001f
R3
10 K
R4
10 K
R1 22 K R2 22 K
RC1
1.5 K
RC2
1.5 KC1 .001
fC2 .001f
RB1 & B2 22 K
D1 D2
Q2Q1
1
2
3
6
7
4
5
E
O
O When power is first applied to the circuit, both transistors begin to conduct. Due to component differences, one will conduct
O harder than the other. The harder conducting transistor drives the other transistor into cut-off. At that time, the conducting
O transistor goes into saturation. For this explanation, let's assume that Q1 is saturated and Q2 is cut off.
O depicts the current paths and voltage drops that provide the base bias for Q1 . As Q1 is in saturation, there will be
O around .7 volts DC across the emitter-base junction. Q2, being cut off, has no current flowing through it and has +Vcc on its
O collector. The voltage dropped across R5 and R3 places a positive voltage on the base of Q1 , keeping it ON. Even though Q2
O is cut off, there will be a small voltage drop over R4 (< 1 volt DC) due to Q1's saturation.
CF351 F05 - 8
Q1 off Q2 on
Q1 on Q2 off.
4
Stable State; Q1 On, Q2 C/ORemains in stable
state until triggered.
D1 FB allows trigger to change
conduction.
C3 .001f
C4 .001f
R3
10 K
R4
10 K
R1 22 K R2 22 K
RC1
1.5 K
RC2
1.5 KC1 .001
fC2 .001f
RB1 & B2 22 K
D1 D2
Q2Q1
1
2
3
6
7
4
5
E
O
1
2a
2
2b
2a
3
3a
D1FB
D2RB
Frequency Out is ½ the Input.
O Q1 in cut-off. As Q2 is saturated, the voltage on its collector will be about 1 volt DC.
O The voltage divider formed by R3 and R5 places a potential of almost zero volts on Q1 's base. Q1, having ground on
O the emitter and almost zero volts OFF I on the base, will be reversed biased and cut off. This state is very stable. Unless an
O external action causes a change, Q2 will remain in saturation and Q1 will remain cut off. As this circuit is constructed from
O NPN transistors, a negative potential applied to the base of the saturated transistor (Q2) would cause it to go into cut-off. The
O action of cutting off Q2 would drive Q1 into saturation. The negative pulse would turn Q2, off placing +Vcc on its collector. R5
O and R3 would divide the voltage, placing a positive voltage on the base of Q1 and turning it on. Now you are back where you
O started, with Q1 on and Q2 off.
CF351 F05 - 10
Wave Form
Q2 on Q1 off.
4
C3 .001f
C4 .001f
R3
10 K
R4
10 K
R1 22 K R2 22 K
Rc1
1.5 K
Rc2
1.5 KC1 .001
fC2 .001f
RB1 & B2 22 K
D1 D2
Q2
Q1
1
2
3
6
7
4
5
E
O
3
3b
1 2a
D1RB
D2FB
2
2b
3a2
a
Frequency Out is ½ the Input.
Stable State; Q2 On, Q1 C/ORemains in stable
state until triggered.
D2 FB allows trigger to change
conduction.
CF351 F05 - 11
SUMMARY
Q2 B Q1 B
Wave Form Analysis
Frequency Out is ½ the Input.
Stable State; Q2 On, Q1 C/ORemains in stable
state until triggered. D2 FB allows trigger to change
conduction.
Stable State; Q1 On, Q2 C/ORemains in stable
state until triggered. D1 FB allows trigger to change
conduction.
Read Signals: Left to Right
Input @ 440 KHz
Differentiated @ 440 KHz
Rectified @ 220 KHz
Output @ 220 KHzQ1 Q2
CF351 F05 - 12
APPLICATION & SUMMARY
The Bistable Multivibrator:.
Has two stable states Requires an input trigger
to change states Has two outputs, Q and
Q’ The outputs are always
opposite The output is taken from
the collector of the transistors
The major uses of a Bistable Multivibrator are:.
Timing Frequency divider Memory storage device Electronic toggle switch
CF351 F05 - 13
REFERENCESBY
PROF.: Dr. Meena mam’s notes
ENDTHANK YOU
