555 Chip Explained - LED Blinker, Buzzer, Siren...
Summary
TLDRThis video tutorial offers an in-depth introduction to the 555 oscillator chip, a staple in electronics for over 50 years. It explains the function of all eight pins and demonstrates how to create simple circuits like LED blinkers and beepers with varying frequencies. The video also covers the impact of different resistor and capacitor values on oscillation speed, introduces the concept of duty cycles, and explores the use of the chip's lesser-known pin five for unique applications. Viewers are guided through building oscillators with fixed and variable frequencies, offering a comprehensive foundation for beginners in circuit design.
Takeaways
- 😀 The 555 oscillator chip is an essential component for beginners in electronics, commonly used for over 50 years.
- 🔌 The 555 chip has 8 pins with pins 1 and 8 serving as the supply voltage connections, pin 1 being ground and pin 8 the positive supply.
- 🔄 Pins 3 and 7 are the two main outputs of the 555 chip, functioning as switches controlled by internal transistors.
- 🔩 The 555 chip operates with two main inputs, pins 2 and 6, which control the flipping of the outputs based on voltage levels.
- 🔄 An additional reset input can override the outputs, but is often left unconnected or connected to the positive supply to disable its effect.
- 🔄 The 555 chip can be easily turned into an oscillator due to its inverting effect on the inputs and outputs.
- 💡 By connecting LEDs to the outputs, one LED will light up when the output is low and the other when it's high, creating an alternating blink.
- ⚡ The frequency of the oscillator can be adjusted by changing the values of the resistor and capacitor in the circuit.
- 🔊 A beeper can be created using a small speaker with the 555 chip, requiring higher frequencies achieved by using lower capacitance values.
- 🔄 Pin 5 of the 555 chip can be used to manipulate threshold values, influencing the frequency and duty cycle of the output.
- 🔄 The duty cycle of the oscillator can be altered by using a potentiometer or by changing the resistor values, allowing for unequal blinking of LEDs.
Q & A
What is the 555 oscillator chip?
-The 555 oscillator chip is a versatile integrated circuit used in various electronic applications, including the creation of oscillators, timers, and pulse generators. It has been in production for over 50 years and is often one of the first chips that beginners in electronics learn about.
How many pins does the 555 oscillator chip have?
-The 555 oscillator chip has eight pins, each serving a specific function, such as supply voltage connections, outputs, and inputs.
What are the functions of pin 1 and pin 8 on the 555 chip?
-Pin 1 is the ground pin, connected to 0 volts, and pin 8 is the positive supply voltage pin, typically receiving a voltage between plus 5 to +15 volts from a DC power supply or battery.
What are the two main outputs of the 555 chip?
-The two main outputs of the 555 chip are pin 3 and pin 7. These outputs can be in two states, high or low, and are controlled by internal transistors acting as switches.
How do the inputs of the 555 chip affect the outputs?
-The inputs of the 555 chip, specifically pins 2 and 6, control the state of the outputs. When the voltage at pin 2 goes below 1/3 of the supply voltage, the outputs flip up. When the voltage at pin 6 goes above 2/3 of the supply voltage, the outputs flip back down.
What is the purpose of the reset pin on the 555 chip?
-The reset pin, when connected to 0 volts, overrides the other inputs and forces the outputs to flip down. It is often left unconnected or connected to the positive supply rail to disable its effect.
How can the frequency of a 555 oscillator circuit be adjusted?
-The frequency of a 555 oscillator circuit can be adjusted by changing the values of the resistor and capacitor used in the feedback loop. Higher resistance or capacitance results in a slower frequency, while lower values result in a faster frequency.
What is the function of pin 5 on the 555 chip?
-Pin 5 on the 555 chip is connected to the internal resistive divider and can be used to manipulate the threshold values for pins 6 and 2, which affects the frequency and duty cycle of the output. It can also be used as a filter to prevent noise on the supply rail from affecting the threshold values.
How can the 555 chip be used to create a variable frequency oscillator?
-A variable frequency oscillator can be created by adding a potentiometer in series with the resistor in the feedback loop of the 555 circuit. Adjusting the potentiometer changes the resistance, which in turn changes the frequency of the oscillator.
What is the purpose of connecting a capacitor to the supply rails in a 555 circuit?
-Connecting a capacitor between the positive and negative supply rails, often referred to as decoupling or bypass capacitor, helps stabilize the circuit by filtering out any noise or fluctuations in the power supply. It is typically a polarized electrolytic capacitor with a value ranging from 100 to 1000 microfarads.
How can the 555 chip be used to create a beeper circuit?
-A beeper circuit can be created by connecting a small speaker to the output of a 555 oscillator circuit. The frequency of the oscillator needs to be high enough for the speaker to produce an audible sound. Capacitors with lower values are used to achieve higher frequencies.
What is the effect of connecting a diode in the oscillator resistor of a 555 circuit?
-Connecting a diode in the oscillator resistor allows the LEDs to blink unequally, changing the duty cycle of the oscillator. Without the diode, the duty cycle is always 50% or higher, but with the diode, any duty cycle can be achieved depending on the ratio of the resistors.
Outlines
🔌 Introduction to the 555 Oscillator Chip
This paragraph introduces the 555 oscillator chip, a common component in electronics, particularly for beginners. It explains the chip's eight pins, including the supply voltage pins (1 and 8), and the two output pins (3 and 7) that function as switches controlled by internal transistors. The paragraph also covers the two main input pins (2 and 6) that determine when the outputs flip based on voltage levels, as well as the less commonly used reset pin. The 555 chip's oscillator function is highlighted, demonstrating how it can create an oscillating circuit with the right components, such as resistors and capacitors, to control the frequency.
💡 Building an LED Blinker Circuit with the 555 Chip
The second paragraph delves into constructing an LED blinker circuit using the 555 chip. It describes how to connect LEDs to the chip's outputs, with one LED lighting up when the output is low and the other when it's high, creating an alternating blinking effect. The importance of stabilizing the circuit with a capacitor across the supply rails is emphasized, along with the impact of varying resistor and capacitor values on the blink rate. The paragraph also explains the role of the internal resistive divider and pin 5 in setting threshold voltages for the inputs, and how manipulating these can influence the circuit's frequency and duty cycle.
🔊 Creating a Variable Frequency Oscillator and Beeper
This paragraph discusses creating a variable frequency oscillator using a potentiometer to adjust the blink rate of an LED blinker circuit. It then transitions to building a beeper circuit with a small speaker, explaining the need for higher frequencies and the use of different capacitor values to achieve this. The speaker is connected via a capacitor to receive the AC signal, not DC, and the frequency can be adjusted to produce different sounds, from clicks to buzzes. The paragraph also touches on experimenting with pin 5, using it to control a blinking LED and create a siren effect.
🔄 Advanced Oscillator Techniques and Applications
The final paragraph covers advanced techniques for the 555 oscillator, such as using pin 7 for feedback to create a more stable oscillator, adjusting the duty cycle with resistor values, and using a diode to create unequal on-off times for the LEDs. It also mentions the possibility of using the 555 chip in non-oscillating circuits, like a flip-flop or monostable timer, and hints at further exploration of these topics in future videos. The paragraph concludes with an invitation for viewers to support the channel and a mention of a bonus circuit, encouraging continued interest and engagement.
Mindmap
Keywords
💡555 Oscillator Chip
💡LED Blinker
💡Beeper
💡Variable Frequency
💡Pin Functions
💡Logic Chip
💡Oscillator
💡Duty Cycle
💡Resistor
💡Capacitor
💡Potentiometer
💡Internal Resistive Divider
💡Output Pin
Highlights
Introduction to the 555 oscillator chip, a common component for beginners in electronics.
Explanation of the 8 pins of the 555 chip, including supply voltage pins 1 and 8.
Description of the two outputs, pin 3 and pin 7, and their binary switching behavior.
Input pins 2 and 6 control the flip of the outputs based on voltage levels.
The reset pin's function and its priority over the other inputs.
Building a simple oscillator using the 555 chip with an inverting effect on the pins.
Use of a resistor and capacitor to control the frequency of the oscillator.
Connecting LEDs to the oscillator to visually indicate the blink rate.
The role of pin 5 in adjusting threshold values and its common applications.
Demonstration of changing the blink rate by altering resistor and capacitor values.
Construction of a variable frequency oscillator using a potentiometer.
Creating a beeper circuit with the 555 chip and adjusting frequency for audible sound.
Experimentation with pin 5 to control the blinking of an LED integrated into the circuit.
Use of pin 7 for oscillator feedback and the need for a pullup resistor.
Adjusting the duty cycle of the oscillator by manipulating resistor values.
Implications of using extremely low or high resistances in the oscillator circuit.
Introduction of non-oscillating 555 chip circuits like the flip-flop and monostable circuits.
Invitation to support the channel for further detailed exploration of 555 chip applications.
Transcripts
so today a video for beginners
explaining a 555 oscillator chip and
some simple circuits with it like an LED
blinker and a beeper or even a beeper
with two frequencies and a variable
frequency blinker I will show the
schematics of these circuits but first
let's explain what all the pins of the
555 oscillator chip do a 555 oscillator
chip has eight pins and in reality it
looks like this and there are different
versions from many different makers and
they're making this one for over 50
years now and it's a very common chip
and for beginners in electronics very
often the first chip they learn about
first let's take a look at the pin one
and eight these are the supply voltage
pins pin one is the ground connected to
0 volts and pin 8 is the positive Supply
voltage and it's typically from plus 5
to + 15 volts from a DC power supply or
from a battery and then it has two
outputs pin three and pin 7 and this is
a logic chip not an analog chip so the
outputs can be just in two states
nothing in between and the outputs are
switched by internal transistors in it
which you can imagine for Simplicity as
switches the pin three can be either
switched to the Z volt rail the ground
or to the positive Supply
Rail and then there is another output
pin 7 called mysteriously discharge
acting sort of similar as this one but
it only switches to the Zer volt rail or
to nothing and they of course
synchronized they always flip at the
same time but this one connected to the
pin 7 only switches to the ground not to
the positive of course in reality this
output is an npn transistor with an open
collector but let's not make it too
complicated so these two pins are the
outputs they work like switches but what
makes these switches flip they flip
based on what happens at the inputs the
555 chip has two main inputs the pins 2
and six plus an additional input reset
the output skan flip based on what
happens at the inputs first let's take a
look at this input pin two when the
voltage at this input goes below 1/3 of
the supply voltage the switches flip up
this output gets the supply voltage on
it and this output is disconnected now
they basically flipped into the upper
position here so now we flip the
switches up and how do we flip them back
down when the voltage at this input pin
six goes above 2/3 of the supply voltage
they flip back down so they're again in
this
position both outputs connected to the Z
volt rail or ground so one input flips
the outputs up when the voltage goes low
enough and one flips them down when the
voltage goes high enough and in most
oscillator circuits these two inputs pin
six and and pin two are connected with
each other so they basically work as
just one input which can flip the
outputs both up and down and there is
one more input which is not used very
often is the reset pin and this flips
the outputs down when it's connected to
0 volts but in most cases it's unused
you can leave the pin unconnected but
it's better to actually connect it to
the positive Supply rail to basically
disable it so it has no effect and of
course the inputs have some priority is
the reset input has the highest priority
so if this is connected to 0 volts it
flips the outputs down and it doesn't
care about the input six and two and
then input two has a lower priority and
the input six the lowest one if you for
example pull pin two under 1/3 of the
supply voltage and pin six
simultaneously above 2/3 of the supply
voltage the pin two has a priority end
so the outputs flip up but this never
happens when these two are connected
with each other there of course but now
let's build a very simple oscillator out
of it the pins have an inverting effect
so it's easy to turn it into an
oscillator when this pair of penis is
pulled higher the output goes low and
when it's pulled lower the output goes
high it's inverting so it can form an
oscillator when basically the output
goes back into the inputs but of course
it shouldn't be connected directly it
has to go via a
resistor now with this feedback it's
basically an oscillator but it would
oate extremely fast so we have to make
it slower by adding a capacitor the
inputs and the here the capacitance the
slower it is the lower the frequency of
the oscillator and also the higher the
resistance of this resistor the slower
the oscillator is or its output
frequency is lower now the circuit
oscillates but we can't see it because
there is no indication so let's connect
some LEDs to it he connected a pair of
LEDs this one lights up when the outputs
are low and the current goes from the
positive Supply rail through this
led into this output and into the Z volt
Rail and when this output is high the
current goes from the supply rail
through the
output through this LED and to the Z
volt rail so it's always one LED on and
the other one off I gave the component
some values these resistors are 560 ohms
it's not critical it can be for example
one kiloohm as well this resistor is 470
KMS and this capacitor is 1 microfarad
ceramic capacitor and the circuit looks
like this the LEDs are alternately
blinking but of course it's a good
practice as you can see to connect a
capacitor to the supply rails between
the positive and the negative like this
for stability of the circuit typically
this capacitor is from 100 microfarads
to 1,000 microfarads and it's an
electrolytic capacitor which is
polarized and it's negative for a z volt
terminal it's marked using this stripe
with a minus symbol which goes to the
first pin of this chip and how this
circuit works when the output is high it
basically charges via this resistor this
capacitor and it's charged until it
reaches 2/3 of the supply voltage and
then it flips and this output is low and
Via this resistor it discharges this cap
until it reaches 1/3 of the supply
voltage and then the output flips back
too high and it keeps repeating so for
example our supply voltage is 6 Vols of
battery let's say so the voltage at this
capacitor and the inputs looks like this
the capacitor charges to 2/3 of the
supply voltage and this charges to 1/3
and this keeps
repeating and the output pin three goes
like this 6 Vol 0 Vol 6 Vol 0 Vols while
the inputs are going between 2 volts and
4 Vols but of course if the supply
voltage was 12 volts it would be going
between 4 volts and 8 volts the
threshold levels always depend on the
supply voltage and these threshold
levels are created by an internal
resistive divider in the chip made of
three
resistors and there is one last
mysterious pin pin five and this one is
actually connected to this divider to
this spot on it and this spot is
actually used as the threshold value for
the pin six and the voltage on this spot
is used as the threshold voltage for the
pin Two And the pin five is very often
unused or it can be connected via a
capacitor to the Z volt rail as some
sort of a filter so the threshold values
are not influenced by the noise on the
supply Rail and this capacitor typically
is 100 nanofarad ceramic or this pin can
also be used to manipulate the threshold
values you can externally change the
voltage on this pin to change the
threshold values for the pin 6 and two
which in an oscillator influences the
frequency and Dy cycle at the output but
let's leave this spin for now and let's
go back to our blinker and let's try to
change the speed of it by changing the
values of these two components when I
replace the 470 kohm resistor using 1
Mega ohm resistor it's blinking slower
the higher the resistance the slower it
is the lower the
frequency and now I have an 82 km
resistor which is much lower resistance
so it should be much faster now and it's
blinking quite fast now let's replace
the 1 microfarad capacitor in the
oscillator using a 10 microfarad
capacitor a higher capacitance should
make it slower again and this one is
electrolytic it's polarized so this pin
has to go to the negative or 0 volt rail
and pin one of the chip let's replace
the capacitor and higher capacitance
makes it run slower the frequency is
lower now let's make an oscillator with
a variable frequency I added a
potentiometer in series with the
resistor in the oscillator here you can
see the potentiometer in the circuit and
by turning the potentiometer I can
change the
speed it's getting
faster and even
faster and the slower
again and here's the schematic of it and
now let's try to build a beeper I will
use this small speaker for it and the
frequency has to be much higher for this
I will replace the one microfarad
capacitor using a 100 nanofarad
capacitor a lower capacitance means a
higher frequency and it can be even
higher until it's so fast you can't even
see it
so I added a speaker to the circuit and
speakers are connected to the output via
a capacitor not directly so they only
get thec voltage not the DC and the
frequency is quite low so it's clicking
and when I increase
it it's
buzzing and to get the frequency even
higher let's replace this one 100
nanofarad capacitor using a 10 nanofarad
capacitor and now it's higher and I can
again adjust
it it works
[Music]
nicely now let's experiment with the pin
five who was a kid my favorite use for
it was to connect a blinking LED to it
it's an LED with a blinker built into it
and this blinking Le when connected to a
power supply just via resistor blinks on
its own thanks to its built-in blinking
circuitry now let's try to connect it to
the pin five it will go from the pin
five to the Z volt Rail and always in
LEDs the longer pin is theod or the
positive so the longer pin goes to the
pin five let's turn it on
and let's add the
El and we have a 2 siren and the is
blinking by the
[Music]
dimly he removed these eles and now we
have a 2o
siren
[Music]
and of course it's schematic and adding
a resistor going from the positive to
the pin five and the LED makes it blink
brighter and changes the behavior a
[Music]
bit and now let's go back from the
Beeper to the blinker to be able to
demonstrate how to use the pin 7 he was
previously connecting the oscillator
resistor from the pin 3 to the pin two
which makes the circuit a bit simpler it
saves one resistor but the feedback for
the oscillator can also go from the pin
seven to the pin 2 and six and this is
actually the recommended way of doing it
because if the resistor goes from the
pin three the oscillator might be
influenced by the load so it might be
better to use the output pin three just
for the load and the PIN 7 for the
oscillator but because the output 7 only
switches to the0 volt rail not to the
positive rail it requires an additional
pullup resistor so this is the main
oscillator resistor and this is the
pullup resistor and when you want to 50%
R the cycle which means the on time for
each LED is roughly equal you're using a
much lower resistance for the pullup
resistor and a much higher resistance
for the oscillator resistor in this
example I'm using just 10 KMS here and
400 20 KS here and because this one is
much higher than this one they blink
about equally but when this one has a
higher value in this example 470 khms
and this one at just 82 khms they are
blinking
unequally the green LED always stays on
much longer than the red one and with a
4.7 microfarad capacitor in the
oscillator which makes it
slower but again uny this resistance is
much lower than this one the LEDs will
blink
unequally and also regarding the
resistors in the oscillator it's not
recommended to use extremely low or
extremely high resistances the lowest
should be something like 4.7 KS and the
highest about 2.2 MGA very low
resistances loads the chip too much and
with very high resistances the leakage
currents show up and this recommendation
applies to both resistors here or the
resistor here in the previous examples
and now I went back to these values
which make an equally blinking
oscillator because this one is much
lower than this one and now let's
demonstrate the pin 4 let's disconnect
it from the positive and connect it to
the Z volt raail and when I do this it
will stop the oscillator now the output
stay low so the red LED is always on and
the current goes like this and of course
when these two resistors are used in the
oscillator the capacitor's charging via
the series combination of both resistors
but it's discharging just via this
resistor the capacitor's charging from
the positive rail through the two
resistors like this and it's
discharging theyjust this resistor and
into the pin seven and now the schematic
is a proper mass and one more example
circuit with an added diode on this
resistor in the oscillator now this
capacitor is charging just via this
resistor instead of the series
combination and it's discharging via
this
resistor and this allows the LEDs to
Blink unequally the other way now the
red one stays on longer in other words
the duty cycle of the oscillator can now
be below 50% instead of over
50% now the waveform is like this when
the green one stayed on longer the
waveform was like
this with the diode you can produce any
duty cycle basically depending just on
the ratio of these resistors but without
the diode the duty cycle is always 50%
or higher and the 555 oscillator can
basically produce square waves for many
different purposes from a fraction of a
Herz up to several 100 KZ and there are
also some circuits with a 555 chip that
are not oscillating for example a bable
circuit which can flip between two LEDs
or can be used for just one to turn
something on and off using push buttons
or a mono stable circuit basically a
timer but this video is getting too long
so if you're interested you can talk
about this in more detail in another
episode so that's it and if you like my
videos please consider supporting this
channel on patreon using the thanks
button and subscribing and big thanks to
all of you who already support me
because this channel couldn't exist
without
you and a bonus
circuit
تصفح المزيد من مقاطع الفيديو ذات الصلة
Complete beginner's guide to using a breadboard
p5.js Coding Tutorial | The Making of Animation - Beautiful Trigonometry
PENGENALAN ARDUINO | BELAJAR ARDUINO 01
Off Delay Timer | how to make off delay timer | how to make delay timer | delay timer
La legge di Ohm - Tutorial di elettronica - #2
How to Use a Breadboard
5.0 / 5 (0 votes)