Sound Reactive LED Circuit Using LM358 Op-Amp and Mic
Summary
TLDRThis video tutorial guides viewers on constructing a sound-reactive LED circuit. It explains the theory behind the circuit, detailing the function of each component including voltage dividers, an op-amp, feedback resistor, diode, and capacitor. The video also covers the step-by-step assembly process, emphasizing the importance of a condenser microphone to detect sound and trigger the LED. The goal is to create a circuit that lights up the LED in response to sound.
Takeaways
- 🎵 The video demonstrates how to create a sound-reactive LED circuit.
- 📚 It explains the theory behind the circuit and the purpose of each component.
- 🔊 The LED turns on in response to sound, as shown by the presenter speaking.
- 👍 The video encourages viewers to like and subscribe for more content.
- ⚡ Voltage dividers are used extensively in the circuit to regulate voltage levels.
- 🔗 A voltage divider is created by two resistors in series, explained with an example.
- 🔄 The script references another video on Ohm's law for further understanding of series and parallel circuits.
- 🔌 The first step in building the circuit involves connecting specific pins to the positive and negative rails.
- 🔄 A feedback resistor is used for negative feedback in the op-amp circuit.
- 💡 A diode is used to drop voltage when there is no sound, ensuring the LED turns off.
- ⏲️ A capacitor is included to filter out noise and prevent the op-amp from getting confused by extraneous signals.
- 🔋 The circuit is designed to work best with a 5-volt battery supply.
- 🎤 A condenser microphone is used to detect sound, changing its capacitance based on the sound it receives.
- 🔧 The final circuit allows sound signals to be processed and the LED to react accordingly.
Q & A
What is the main purpose of the video?
-The main purpose of the video is to demonstrate how to make a sound-reactive LED and explain the theory behind its operation.
What is a voltage divider and how is it used in the circuit?
-A voltage divider is a circuit with two resistors in series that creates a smaller voltage at its node by combining positive and negative voltages. It is used in the circuit to drop the voltage at specific points.
Why are there many voltage dividers in the circuit?
-There are many voltage dividers in the circuit because they help to regulate and adjust the voltage levels where needed, which is essential for the proper functioning of the circuit.
What is the role of the operational amplifier (op-amp) in the circuit?
-The operational amplifier (op-amp) takes two input voltages (inverting and non-inverting) and produces an output. It is used to amplify the difference between the two input voltages.
How is the voltage divider formed with resistors?
-The voltage divider is formed by connecting a 10 kilo ohm resistor between pin 3 (non-inverting input) and the negative rail, and another 10 kilo ohm resistor from pin 3 to the positive rail.
What is the purpose of the feedback resistor in the circuit?
-The feedback resistor, which is a high resistance resistor, provides negative feedback to the op-amp. It is connected between the inverting input and the output to stabilize the circuit.
Why is a diode used in the circuit?
-A diode is used to drop the voltage when there is no sound, ensuring the LED turns off. The diode's characteristic of dropping voltage when current runs through it is utilized here.
What is the function of the capacitor in the circuit?
-The capacitor, specifically a 0.47 microfarad capacitor, is used to filter out excess noise from the signal, preventing it from confusing the op-amp.
How is the LED connected in the circuit?
-The LED's negative (cathode) is connected to the diode, and its positive (anode) is connected to the positive rail through a 270 ohm resistor.
What is a condenser microphone and how does it work?
-A condenser microphone changes its capacitance based on the sound it receives. When it receives sound, the capacitance increases and this change is sensed by the circuit.
How does the sound signal travel through the circuit?
-Sound signals enter through the condenser microphone, get regulated by the voltage divider, filtered by the capacitor, and then travel through the feedback resistor to the op-amp, where it is compared and ultimately controls the LED's state.
Outlines
💡 Building a Sound-Reactive LED Circuit
This paragraph introduces the project of creating a sound-reactive LED using an op-amp circuit. The host explains the importance of each component and how they work together. Voltage dividers are discussed, which are essential for regulating voltage levels in the circuit. The role of resistors, specifically 10 kilo ohm resistors, in creating these voltage dividers is highlighted. The operational amplifier (op-amp) is briefly reviewed, explaining its function of taking two input voltages and producing an output. The first step in the circuit assembly involves connecting pin 8 to the positive rail and pin 4 to the negative rail. A voltage divider is then formed with two 10 kilo ohm resistors at pin 3, which is the non-inverting input, to lower the voltage. The necessity for a feedback resistor, which is a high resistance resistor, is explained, and its placement between the inverting input and the output is detailed.
🔊 Completing the Sound-Reactive LED Circuit
The second paragraph continues the explanation of the sound-reactive LED circuit. It discusses the use of a diode to drop voltage when there is no sound, allowing the LED to turn off. The placement of the diode in relation to the op-amp output is described. A 0.47 microfarad capacitor is introduced to filter out excess noise and prevent the op-amp from getting confused by unwanted signals. The assembly of the circuit is detailed, including the connection of an LED to the diode and the positive rail through a 270 ohm resistor. The importance of using a 5-volt battery supply is mentioned, as a 9-volt battery may not provide the necessary sound sensitivity. The function of a condenser microphone, which changes its capacitance based on the sound it receives, is explained. The final steps of connecting the microphone to the circuit and the flow of sound signals through the circuit are outlined, concluding with the complete setup of the M358 op-amp circuit.
Mindmap
Keywords
💡Sound-Reactive LED
💡Voltage Divider
💡Op-Amp
💡Feedback Resistor
💡Diode
💡Condenser Microphone
💡Resistor
💡Capacitor
💡Ohm's Law
💡Series Circuit
💡Voltage Regulation
Highlights
Introduction to creating a sound-reactive LED
Explanation of the theory behind the sound-reactive LED
Demonstration of LED turning on with sound
Importance of voltage dividers in the circuit
Detailed explanation of how a voltage divider works
Purpose of multiple voltage dividers in the circuit
Brief review of the operational amplifier (op-amp)
Step-by-step guide to connect the op-amp pins
Formation of a voltage divider with 10 kilo ohm resistors
Role of the feedback resistor in the circuit
Use of a one mega ohm resistor for feedback
Explanation of how a diode drops voltage in the circuit
Placement of the diode for optimal voltage drop
Necessity of a capacitor to filter out noise
Use of a 0.47 microfarad capacitor for noise filtering
Connecting the LED to the circuit
Explanation of why a 270 ohm resistor is used for the LED
Optimal voltage for the circuit operation
Function of a condenser microphone in the circuit
Connection of the condenser microphone to the circuit
Final assembly and completion of the op-amp circuit
Detailed explanation of how the circuit operates with sound
Transcripts
[Music]
[Laughter]
[Music]
hello everyone
in this video we will make a sound
reactive led
we will learn how it works the theory
behind it
and why each component is there so as
you can see
as i'm talking the led is turning on
so i hope you enjoy this video and if
you do please leave a thumbs up and
subscribe to my channel
so as you may have noticed in this
circuit diagram
there are a lot of voltage dividers
so for example this right here is a
voltage divider
and this right here is a voltage divider
a voltage divider
is where there are two resistors in
series
just like this and if you don't know
what series in parallel is
you can check out my video on ohm's law
in the description
so we have here the 10 kilo ohm resistor
is like this
it takes positive voltage and negative
voltage
it brings them together like this and
then it stops at the node right here
and an output is fed off so basically
it takes a regulated voltage combines
the positive and negative together
and then it creates a smaller voltage at
its node right there
there are a lot of these in the circuit
because sometimes
you don't want a certain amount of
voltage and you want it to drop
increase or decrease so that is why in a
lot of circuits that you need to use
these voltage dividers
a quick review on the op-amp
is it's an operational amplifier it
takes two input voltages and inverting
and non-inverting
and splits out an output so guys our
first step is to connect
pin 8 to the positive rail and pin 4 to
the negative rail
after that we want to form a voltage
divider with two 10 kilo ohm resistors
so right here at pin 3 or the
non-inverting
input you want to create a voltage
divider because we want to drop down the
voltage right there
so we take a 10 kilo ohm resistor
and we put it on pin 3 we put that to
the negative rail
and put the other one to the positive
rail just like this
and then pin 8 to the positive row
so next after the voltage divider our
circuit needs a feedback resistor
so what a feedback resistor is it's a
high resistance resistor and it goes on
one of the inputs and one of the outputs
it acts as negative feedback for this
optic
so we're going to take a one mega ohm
resistor
and place it between the inverting input
and the output
so like this we're going to place it on
pin two
which is the inverting input and we're
going to place it
also on pin one
we for our led to be sound reactive
and turn off when there is no um
sound coming we need something to drop
the voltage
and a diode is a really good candidate
to do that
this is because if current runs through
a diode
what happens is the voltage drops a lot
because of its characteristics as you
can see in the video
in the description about diodes so we're
going to place this cathode
facing the output so the cathode
is this little line right there so we're
going to place it
like this so we place this cathode
on the output and its anode out in the
distance
so you can connect it to an led
so there because this lm350 op-amp once
you receive voltage divider and all the
signals coming at it
it releases so much extra voltage that
we do not need
so this diode drops it as heat
our next thing is that we need capacitor
to filter out
excess noise that are coming from here
so it doesn't get confused this little
op-amp
so we're going to use a 0.47 microfarad
capacitor
to do this so we're gonna take a wire
and place it on the inverting input or
pin two
just like this then we're gonna take the
capacitor
and place one of its pins on that
then we're going to form a voltage
divider using 10k resistors again
as we take the 10 kilo ohm resistor and
place the other side of the capacitor
this one one to the negative
and one to the positive just like this
so if you may have noticed that i um
took out the 10 kilometer sister for a
minute
and i put it back right there so our
next step
is to take an led in place it's negative
or it's cathode on the diode
and take its anode or its positive
and connect it to the positive rail and
use a resistor to do this
so you can use a 270 ohm resistor
because this circuit works best on 5
volts of battery
because if you use a 9-volt battery
supply
sometimes it doesn't pick up that much
sound
and it um the led stays on because of so
much
voltage and there's not enough to get
dropped by this
diode denser microphone if you don't
know
a condenser microphone changes its
capacitance based on the sound it
receives
so for example if it receives a lot of
sound the capacitance
increases and gets sensed by the circuit
if there's no sound
then it won't get sensed by the circuit
and then
the led will turn off it's a wire
connecting
to the negative rail so we connect the
condenser mics negative over there
and it's positive to the side of the
capacitor where the voltage divider was
so right over here now the sound and the
signals can travel all around the
circuit
so now our m358 op-amp circuit is
complete
so how the circuit works is um sound
gets traveled into this condenser mic
the condenser rack is getting powered
right here
then the signal travels all the way over
here and gets
regulated and the voltage just gets
smaller and
gets better because of this voltage
divider right here
after that it travels out the node over
here you can follow this arrow
and then it travels to the 0.47
microfarad capacitor to get filtered
then right here it comes down here
signal or the electrons or
current and let me just write that down
i stands for current by the way so then
it goes right here and this acts as a
feedback resistor for this op-amp
so then it goes through the feedback and
out in the output
and this inverting um non-inverting
input actually
basically acts as just a another output
so the comparators can have two inputs
because it doesn't make sense if you
have one input because then you just
have that as an output
so this right here acts as another input
then it goes right here
and this diode drops the voltage by
about three volts
and then it goes to this led to get
power
you
Ver Más Videos Relacionados
Off Delay Timer | how to make off delay timer | how to make delay timer | delay timer
How to Solve Any Series and Parallel Circuit Problem
Beginner Electronics - 8 - First Circuit!
Complete beginner's guide to using a breadboard
Model Traffic Lights Circuit | 555 Timer Project #15
What is an operational amplifier?
5.0 / 5 (0 votes)