Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skillsβperfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Introduction to Monostable Multivibrator
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Today, we'll learn about the monostable multivibrator. Can anyone tell me what it means to have a stable versus a quasi-stable state?
Uh, isn't the stable state the one that doesn't change?
Exactly! The stable state is where the circuit remains under normal conditions. When we apply a trigger, it temporarily shifts to a quasi-stable state, which is less stable. It only lasts for a specific time.
And how does it return to the stable state?
Good question! It returns when the timing conditions are met, mainly influenced by the resistor-capacitor combination in the circuit.
So the RC time constant is important?
Exactly! Remember, RC stands for the time it takes for the capacitor to charge or discharge is key to how long the circuit stays in its quasi-stable state. Let's move on to how the trigger pulse initiates this process.
Functionality of the Circuit
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
When we apply a trigger, what do you think happens inside the circuit?
Does the transistor switch states?
Yes! Specifically, transistor Q2 switches off, and that makes the output go HIGH. But this also allows capacitor C to start charging. Student_2, can you explain what happens next?
Right! As the capacitor charges, it affects the base voltage of Q1, eventually turning it on?
Exactly! When Q1 turns on, it causes Q2 to turn back off. This completes the cycle back to our stable state. Great job!
So it's like a relay that toggles based on input!
That's a nice analogy! This toggling behavior is indeed the essence of the monostable multivibrator.
Retriggerable Monostable Multivibrator
Unlock Audio Lesson
Signup and Enroll to the course for listening the Audio Lesson
Now, letβs talk about a special type called the retriggerable monostable multivibrator. What does 'retriggerable' mean?
It sounds like it can be triggered multiple times while in the quasi-stable state?
Exactly! If we apply new trigger pulses while itβs still active, it can extend the duration of the output pulse.
So how is the output pulse width calculated then?
Great question! If n trigger pulses are received within a certain interval, the output pulse width would increase, calculated as (nβ1)T + T.
That sounds really useful for applications where timing is critical!
Exactly! This ability to extend the pulse based on multiple triggers makes it quite versatile in digital circuits.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
In this section, we explore the functioning of a monostable multivibrator, which operates in a stable state until triggered to switch to a quasi-stable state, where it remains for a brief period before returning to the stable state. This chapter also covers the retriggerable variant, highlighting its ability to extend the output pulse based on subsequent triggers.
Detailed
Detailed Summary
A monostable multivibrator (or monoshot) is a type of multivibrator circuit that has one stable state and one quasi-stable state. Initially, the circuit resides in a stable state; it transitions to the quasi-stable state upon receiving a trigger pulse. This quasi-stable state exists for a predetermined duration before reverting to the initial stable state.
The basic operation relies on the coupling of transistors where one transistor (Q2) remains in saturation, receiving bias from the power source through a resistor (R). If a trigger pulse is applied, Q2 turns off, leading to a high output state. As the capacitor (C) charges through R, the base voltage of Q1 eventually exceeds its cut-in voltage, which allows Q1 to conduct, turning off Q2 and restoring the circuit back to its stable state. The duration of the quasi-stable state depends on the values of R and C, establishing the time constant.
The section also discusses the retriggerable monostable multivibrator, which can respond to trigger pulses even while in the quasi-stable state, extending the output pulse width according to the number and timing of these triggers. This functionality allows the circuit to produce a longer output pulse reflecting the sequence of trigger events.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Definition and Functionality
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
A monostable multivibrator, also known as a monoshot, is one in which one of the states is stable and the other is quasi-stable. The circuit is initially in the stable state. It goes to the quasi-stable state when appropriately triggered. It stays in the quasi-stable state for a certain time period, after which it comes back to the stable state.
Detailed Explanation
A monostable multivibrator, often referred to as a monoshot, operates by having one stable output state and one quasi-stable output state. Initially, the circuit is in a stable state. When a triggering event occurs, it shifts to a quasi-stable state, which persists for a predetermined duration. After this time elapses, the monostable multivibrator automatically reverts to its stable state. This means it stays in the second state only momentarily and does not remain there permanently.
Examples & Analogies
Imagine a light switch in a room. When you flip the switch on, the light stays on (stable state). If you give the switch a quick tap (trigger), the light might blink on briefly (quasi-stable state) before going back to being off. Just like the light switch, a monostable multivibrator is designed to respond to a trigger and return to its original state after a set duration.
Circuit Operation
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Figure 10.4 shows the basic monostable multivibrator circuit. The circuit functions as follows. Initially, transistor Q2 is in saturation as it gets its base bias from +VCC through R. Coupling from Q2 collector to Q1 base ensures that Q1 is in cut-off. Now, if an appropriate trigger pulse induces a transition in Q2 from saturation to cut-off, the output goes to the HIGH state.
Detailed Explanation
The operation of the monostable multivibrator is illustrated using a specific circuit setup. Initially, transistor Q2 conducts, allowing an electric current to flow, which keeps Q1 turned off. This configuration ensures that Q2 remains in a saturated state. When a trigger pulse is applied to Q2, it causes Q2 to stop conducting (transition to cut-off). As a result, the output voltage rises to a high state. This action is significant as it is the trigger pulse that initiates the change in output.
Examples & Analogies
Think of a person holding a balloon. When someone taps their hand (the trigger), they let go of the balloon, and it shoots up (HIGH state). Just like the balloon that moves to a different position when tapped, the monostable multivibrator changes its output state promptly in response to a trigger pulse.
Time Constant and Return to Original State
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Since there is no direct coupling from Q2 collector to Q1 base, which is necessary for a regenerating process to set in, Q1 is not necessarily in saturation. However, it conducts some current. The Q1 collector voltage falls by I *Rc1, and the Q2 base voltage falls by the same amount, as the voltage across capacitor C cannot change instantaneously. To sum up, the moment we applied the trigger, Q2 went to cut-off and Q1 started conducting.
Detailed Explanation
In this part of the monostable multivibrator's operation, once Q2 transitions to the cut-off state due to the trigger, it no longer provides the necessary voltage to keep Q1 off. A capacitor in the circuit starts charging, which influences the base voltage of Q1. As Q1 receives enough voltage, it begins to conduct. This transition to the conducting state allows Q1 to pull down the output voltage, thus returning the circuit eventually to its original stable state after a predetermined time, dictated by the RC time constant.
Examples & Analogies
Consider a water balloon (representing Q2) that is released (cut-off) when squeezed (triggered). Initially, the water inside stays in place (stable). However, as soon as the balloon is released, water can flow out (current through Q1) but the rate depends on how tightly you had the balloon compressed (the RC time constant). Eventually, the balloon's tension returns to normal (state returns to stable) once the water has flowed out.
Time Period and Control Over Output Duration
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Whenever we trigger the circuit into the other state, it does not stay there permanently and returns back after a time period that depends upon R and C. The greater the time constant RC, the longer is the time for which it stays in the other state, called the quasi-stable state.
Detailed Explanation
The time that the monostable multivibrator remains in its quasi-stable state (after being triggered) is directly related to the values of the resistor (R) and capacitor (C) in the circuit. The product of these values, known as the time constant (RC), determines how long the output will be high before reverting back to its stable state. Thus, by altering the values of R or C, we can extend or shorten the duration of the quasi-stable output.
Examples & Analogies
Imagine a stopwatch (RC circuit) that you start when a timer (trigger) goes off. The longer you set the time on the stopwatch (increasing RC), the longer it takes before it stops (returns to stable). You can think of the stopwatch as a way to control how long the output will remain high before resetting.
Retriggerable Monostable Multivibrator
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
In a conventional monostable multivibrator, once the output is triggered to the quasi-stable state by applying a suitable trigger pulse, the circuit does not respond to subsequent trigger pulses as long as the output is in quasi-stable state. After the output returns to its original state, it is ready to respond to the next trigger pulse. There is another class of monostable multivibrators, called retriggerable monostable multivibrators.
Detailed Explanation
A typical monostable multivibrator will not acknowledge additional trigger pulses until it has returned to its stable state. Conversely, a retriggerable monostable multivibrator can accept new trigger pulses even while it is still in the quasi-stable state. This means that if multiple triggers are applied in quick succession, the monostable circuit adjusts its output width accordingly, prolonging the time it stays in the high output state based on the number of triggers received.
Examples & Analogies
Think of a chef cooking (the monostable state). Usually, once he starts cooking a particular dish (trigger), he's set on that one dish until it's done (returns to stable). However, if he has a special multipurpose stove (retriggerable) that allows him to add more ingredients while cooking (additional triggers), he can extend the recipe (keep the output state high) depending on how many extra ingredients (triggers) he adds while already cooking.
Output Pulse Width Calculation
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
In this class of monostable multivibrators, if n trigger pulses with a time period of T are applied to the circuit, the output pulse width, that is, the time period of the quasi-stable state, equals (nβ1)T + T, where T is the output pulse width for the single trigger pulse and T < T.
Detailed Explanation
Retriggerable monostable multivibrators have a unique output characteristic. If multiple trigger pulses are sent into the circuit while it is still in the quasi-stable state, the effective output pulse width becomes a function of both the number of triggers and the duration of each trigger. The total output duration can be computed as (nβ1) times T (the duration of the quasi-stable state for one trigger) plus an additional T. This formula helps in determining how long the output will stay high based on the frequency of incoming triggers.
Examples & Analogies
Imagine a train station where each incoming train (trigger pulse) can extend the time you spend waiting for your ride (quasi-stable state). If the train arrives every 10 minutes (T), and 5 trains show up in succession (n=5), you will wait for a total of 40 minutes for your ride because of how frequently the trains arrive (total duration equals (n-1)T + T). This analogy illustrates how retriggerability works in a monostable circuit.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Monostable Multivibrator: A circuit that has one stable and one quasi-stable state.
-
Trigger Pulse: Input signal that initiates the transition of the circuit to the quasi-stable state.
-
RC Time Constant: The product of resistance and capacitance that determines how long the circuit stays in the quasi-stable state.
-
Retriggerable Multivibrator: A type that allows extending the output pulse duration based on additional triggers.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
A monostable multivibrator in a timing circuit to control the duration of an LED signal when a button is pressed.
-
Using a retriggerable monostable multivibrator to ensure an alarm sounds for a longer duration if the button is pressed repeatedly.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
π΅ Rhymes Time
-
In a monostable land, one state is grand. Trigger it fast, for a pulse that's cast.
π Fascinating Stories
-
Imagine a traffic light that turns green for a short time when a button is pressed. The moment is brief but bright, just like a pulse from a monostable multivibrator!
π§ Other Memory Gems
-
Remember 'M' for monostable, meaning one state, and 'Q' for quasi, meaning itβs not quite there!
π― Super Acronyms
MVS - Monostable Variable State
- it shifts from a stable to a quasi-stable state upon triggering.
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Monostable Multivibrator
Definition:
A circuit with one stable state and one quasi-stable state that outputs a triggered pulse.
-
Term: QuasiStable State
Definition:
A temporary state that the circuit enters after receiving a trigger pulse.
-
Term: Trigger Pulse
Definition:
An input signal that causes a monostable multivibrator to switch states.
-
Term: Output Pulse Width
Definition:
The duration for which the circuit remains in the quasi-stable state.
-
Term: RC Time Constant
Definition:
A measure of the time required for the capacitor to charge or discharge in the circuit.
-
Term: Retriggerable Multivibrator
Definition:
A monostable multivibrator that can respond to new trigger pulses while in the quasi-stable state.