Circuito temporizador monoestable, con el NE555 | Ensamble paso a paso

Multivibrator Monoestable Circuit Tutorial

Introduction to the Circuit

• This video introduces a monostable multivibrator circuit, aimed at beginners in digital electronics. The presenter emphasizes its utility for learning about electronic functions and applications.

Functionality of the Monostable Multivibrator

• Upon pressing a button, the LEDs remain lit for a predetermined duration, demonstrating the circuit's functionality. This setup is commonly used in alarm systems with sensors and sirens.

• The monostable multivibrator changes state when triggered by an external pulse (button press) and maintains this state for a specific time determined by R1 and C1 components before returning to its original state.

Circuit Components Overview

• The circuit will be powered by a 5V source, activated via a normally open (NA) push button connected to pin 2 of the timer IC (N55). A resistor of 1kΩ connects from pin 2 to positive voltage.

• Key components include:

• N55 timer IC

• Capacitors: C1 (100μF), additional capacitors of varying values.

• Resistors: R1 (3.6kΩ), R2 (10kΩ), R3 (330Ω).

• Up to ten diodes can be connected in parallel for visual output indication.

Assembly Instructions

• The assembly begins with connecting power rails on the protoboard, ensuring proper connections between positive and negative terminals as needed based on board design. Adjustments may be required depending on protoboard configuration.

• The N55 timer has eight pins; correct placement is crucial:

• Pin connections include linking pins to positive or negative as per schematic instructions.

• Pins 6 and 7 are bridged together with a resistor leading to positive voltage while also connecting capacitors appropriately based on polarity requirements.

Wiring Details

• Specific wiring details include:

• Connecting pin 2 through a resistor to positive voltage while integrating the push button into this pathway.

• Output from pin 3 leads through another resistor towards LED indicators, ensuring correct orientation for diode connections based on their anode/cathode specifications.

This structured approach provides clarity on building and understanding the monostable multivibrator circuit effectively while highlighting essential components and their roles within the system.

Connecting Diodes in Parallel

Setting Up the Circuit

• The process begins with connecting three diodes in parallel, ensuring that the anode of each diode is connected to the positive side and the cathode to the negative.

• A maximum of 10 diodes can be connected in this configuration, allowing for flexibility in circuit design.

Testing the Circuit

• The timer's pin 3 can deliver a maximum of 200 milliamperes, requiring only a 330-ohm resistor for proper functioning.

• After powering the protoboard with a 5V supply from a cellphone charger, initial tests are conducted using a 100 microfarad capacitor. LEDs light up briefly upon pressing a button.

Capacitor Variations and Their Effects

Changing Capacitors

• Replacing the initial capacitor with a larger one (470 microfarads) results in longer LED illumination time, approximately 2 to 3 seconds.

• Further testing with a 1000 microfarad capacitor shows even longer LED activation time, lasting around 6 to 7 seconds.

Adjusting Resistance

• The resistance is increased from 3.6k ohms to 10k ohms while keeping the smaller capacitor (100 microfarads), which extends LED on-time slightly.

• With further adjustments using capacitors of higher capacity (like another at 470 microfarads), LED duration increases again.

Calculating Time Based on Components

Applying Formulas

• The formula used for calculating time based on resistance and capacitance is: textTime = 1.1 times C1 times R1 .

• Converting values into appropriate units: C1 = 1000/1000 = 0.001 text farads ; R1 = 10k = 10,000 text ohms .

Final Testing