In this post we will learn how to assemble an IC 555 astable circuit for generating interesting LED flasher and fader light effects with some minor modifcationbs and enhancements.
Why use an IC 555 Astable
The astable multivibrator mode is the most fundamental mode of operation of the IC 555. In this mode it basically functions like a free running oscillator. If this oscillator rate is reduced sufficiently, can be used for driving LED lights.
The wiring at the output can also be further modified for achieving interesting variations and light illumination patterns over the connected LED.
Some of the practical ways of this is explained here, circuits diagrams of LED flasher, ghost effect generator, alternate blinker, light fader etc are also included.
The article explains a few interesting and simple LED blinker circuit configurations using the ubiquitous IC 555.
The basic flashing mode has been kept intact yet various different attributions are provided to the circuit with its flashing rate and pattern.
The IC 555 is a complete package for the hobbyists. You can build numerous interesting circuits with this chip and make it to work as virtually any way you desire.
Though the circuit provides us with many application ranges, flashers configurations are more commonly associated with these chips.
These can be made to blink all types of lights at different rates depending upon individual preferences.
You can flash LEDs, torch bulbs, string lights or even mains AC lamps with circuits incorporating this IC.
Basically, to configure the IC as a flasher or blinker, it’s connected with its fundamental astable mutivibrator mode.
This configuration in fact requires just a couple of resistors and a couple capacitors to kick start the said functions.
Once the chip is assembled as an astable, we can go ahead and enhance the output in many different ways to get outstanding visual treats.
Let’s learn how a few fabulous IC 555 circuits with LED can be built with the following discussions, but first we would like to know what materials are needed for this.
Being a hobbyist you would want to have a bunch of assorted resistors in your box of goodies and also some selected values of capacitors. For the present projects you would require a handful of different value resistors and capacitors.
Parts List for the proposed flasher and fader circuit using IC 555
Resistors rated at ¼ watt, 5 %, unless otherwise stated.
Resistors – 1 K, 10 K, 680 Ohms, 4.7 K, 100 Ohms, 820 Ohms, 1 M etc.
Capacitor – 0.01 uF, 470 uF, 220 uF, 1 uF
Zener diode – 5.1 volts, 400 mW
LED – Red, Green, Yellow 5mm
IC 555
IC 555 Pinouts
Creating Flashing and Fading LED Effects using IC 555 Circuit
The first figure shows the basic configuration associated with 555 ICs, here it is connected as an astable multivibrator. The resistors and the capacitor 1 uF can be experimented with to get different rates of blinking over the connected LED.
The LEDs can also be used with oter colors. The 1 K resistor can be replaced with lower values for increasing the intensity of the LED, however it should not be redced below 330 Ohms. Alternatively the 1 M resistor can be interchanged with a pot for attributing the circuit with variable blinking rate feature.
Making a Police Revolving Light Effect
The above circuit can be suitably modified for producing a revolving, flashing police light effect to the above constructed circuit.
Here by adding a network of a zener diode / resistor / capacitor, to the output of the circuit, just as shown in the figure, we can acquire a very peculiar effect with the generated illuminations of the LED.
The LED initially glows bright, then slowly dies down, but intermittently gives a high intensity pulse producing the discussed police warning roof light indicator illusion.
Random Light Effect Generator Circuit
The configuration shown in this figure enables us to use the circuit to generate random light patterns over the connected group of LEDs.
As shown, three LEDs are connected in conjunction with a couple of resistors and a capacitor. The two LEDs connected in parallel but with opposite polarity, flasg alternately at a particular rhythm while the third LED fluctuates at some other random rate.
The above effect can be simplified by the circuit shown below. Here, the LED which is connected to the 1 K resistor blinks at the fixed blinking rate, but the next LED which is connected to the ground switches rapidly at some other defined rate.
Adding a Spooky Effect to the LED
If you want to produce some strange illumination pattern over the LED discussed through the above circuits, them it can be simply done using just a couple of resistors at the output of the IC.
As can be seen in the figure, two resistors and a single resistor are connected at the output of the IC in a special way. The network switches ON the LED sharply, but switches it OFF slowly, producing quite a creepy visual effect.
Alternate Flasher Circuit
This configuration is pretty straightforward, as we all know; two LEDs can be connected to the IC output for generating an alternate blinking pattern over the connected LEDs.
The above circuit can be further modified as shown below by complely disarranging the network with the shown type. Here the LEDs though blink alternately, the intensity may fluctuate from dim to bright over the LEDs.
Light Fader Circuit Using IC 555
A very interesting light fading effect can be achieved by wiring up the IC 555 circuit as per the diagram shown below. The circuit switches ON the LED very gradually and does the same while switching it OFF, that is instead of shutting it off abruptly, does it very slowly.
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Solomon says
Ok sir thank u very much
Solomon says
Thank you very much sir, please one more question, is it increase in values, increase in flash rate or decrease in values increase in flash rate?
Swag says
it is the opposite, you can easily experiment all these by practically testing it…
Solomon says
Thank u sir,
1. what is the function of 1M Pot?
2. In the link you referred me to, Which capacitor and resistor determine the flash rate?
Swag says
The 1M pot and the 1uF capacitor values determine the flashing rate
Solomon says
Questions sir,
1. for 4th circuit you referred me to, can i add red LED to say 4 or 5 and connect them in series, and add the green also?
2. Does the two LEDs (red and green) swap their illumination? At which time interval?
Swag says
yes you can do that if the supply is 12V.
yes they will swap at a rate decided by the capacitor and resistors values
please use the following design
https://homemade-circuits.com/wp-content/uploads/2011/12/555-5-2.png
Solomon says
Hello sir, i greet u. Am interested on this article, i need a circuit whereby i will connect 8 LEDs in series 4 red 4 green, the red LEDs will illuminate for 5 seconds as soon the time elapsed, it will shut off then the green LEDs will also illuminate at the same time interval alternating, which of the circuit you posted should i use?
Swag says
Solomon, please try the 4rth design for your requirement…
Galo says
So on the Light fader circuit I need 9pc LED do i just add them in array replacing the 2 led in your example using 5v input, or do i have to add 100 ohms resistor on each led I add?
Swag says
9 may not work at 12V, you can add at the most 4 to 5 LEDs, high bright 3.3V rated 20mA type
Farhan says
Sir i have made This circuit but when run more than 20 minute it direct burn the ic
Here using capacitor 100 uf 50v
Power supply is 15 v 3000mAh
Please sir solve this
I accutally want a circuit which can flash a led by 15 volt and 3000mAh power supply
But need slow flash rate
Thanx sir
My circuit diagram is here : https://drive.google.com/file/d/11PKYPB2OZN61wWxFzd61Y7zfwHfPVw-33w/view?usp=sharing
Swag says
Farhan, it is simply because your power supply is not supplying 15V but much above that. use a 7805 IC, or a 7812 IC after the power the supply to correct the supply for the IC and that will solve the issue
By the way the pin#3 LED polarity looks wrong to me, the cathode should be towards the ground.
Farhan says
Sir it will be ok if i use voltage divider by registor ??? For step down into 6-7 volt ..
Swag says
voltage divider will reduce current and your LED will become very dim…you can use the following concept instead:
https://homemade-circuits.com/simplest-dc-cell-phone-charger-circuit/
Vaisakhan says
Hello Swagatam,
I am looking for a fading effect circuit for 4 pin RGB LED with out using Arduino. Preferably for 10 leds. Can you help in this regard? Thanks in advance.
Swag says
Hello Vaisakhan, you can try the following concept, make the IC 555 oscillation slower to create slower fading, rising effect.
https://homemade-circuits.com/2015/09/rotating-beacon-led-simulator-circuit.html
Sidhesh dessai says
Ok sir thanks I’ll try this , n I want one more circuit where i can use a siren at a set intervals eg
30 min will remain off n after 30 min it will on for 20 second to siren and again 30 min off so idea is after every 30 min siren should on for 20 seconds n with day night on off , it should work only in night to drive away wild animals
Thanks
Swag says
Hi Sidhesh, you can use the following simple circuit for the siren:
https://3.bp.blogspot.com/-L9gXRB3GcDc/Vvek1mJUGOI/AAAAAAAANZE/ocPbYVXjnQMDKpxwDB0sd2fu5uqlJkutw/s1600/pwm%2Bcircuit.PNG
adjust the pot to get the required 30/20 OFF/ON ratio.
if the siren current specification is bigger than 200mA then you may have to employ a transistor driver at pin#3 of the IC to drive the siren optimally.
for day night operation do the following modification:
connect pi#4 of the IC to the positive line through a 330K resistor, and connect an LDR from pin#4 to ground. This will keep the IC disabled during daytime, and activate it during evening. select LDR whose resistance in ambient day light is less than 100K
Sidhesh dessai says
Hi sir For Alternate Flasher Circuit pls tell what to change to get output of 12v dc to connect 12v dc led bulb
Thanks
Swag says
Hi Sidhesh, no need to change anything, if your supply voltage is 12V then the input from pin#3 will be also 12V
Sidhesh dessai says
Hi sir I already tested it with 12v dc bulb it’s not getting that much power
Swag says
if the bulb is higher than 200ma then you may have to put a transistor at pin#3 of the IC and use the bulb at the collector side of the transistor.
if the bulb current is within 500mA you can use 2N2222 for the transistor or any other similar.
Paul says
Sir Swagatam,
Sir is there any circuit that you have publish as replacement for a 12v motorcycle flasher for use with LED bulbs? that i can assemble, i have a very little knowledge in electronics, can you give me a link to try and make one.
Thank you very much for your help sir..
Paul
Swag says
Hi Paul, you can try the flasher circuit explained in this article, just replace the bulb section with 3 series bulbs of 1 watt each with a 6 ohm 2watt resistor…this will give the circuit that you are intending to build.
https://homemade-circuits.com/2011/12/build-simple-how-to-build-universal.html
the buzzer section is optional.
KAILAS DUDHBARVE says
Dear Swagatam,
I want to make LED waterfall curtain at home. what circuit I should use to control it.. can you please suggest the controller circuit and how to connect each LED string to the controller, so that the chaser, sequencer and waterfall effect can produce.
Swagatam says
Dear Kailas,
I think you can try the following circuit with some minor adjustments for getting a waterfall effect
https://homemade-circuits.com/2015/11/led-meteor-shower-rain-tube-circuit.html
Swagatam says
No it won't because it has an internal 100k series resistor
ubaid says
Dear Sir,
My Question is if ic 555 Rest pin
No,4 Recive continue Low signal
From another ic 7404.ic 555 will
Heatup and Damage?
Nelio Abreu says
Hi,
Can one of these circuits produce this efect:
1º Starting slow increasing brightness up to a certaing level during 3 seconds
2º Give a quick flash to full brighness at say 1 second
3º Starting slow dcreasing brightness during 3 seconds
4º Remain off for 1 second and repeat process again
?
Best Regards.
NA
Swagatam says
I think you are referring to a rotating beacon kind of light effect, right?
No that may not be possible with the above configurations, you can try the following one instead
https://homemade-circuits.com/2015/09/rotating-beacon-led-simulator-circuit.html
Ashok Dhenge says
Can we use relay instead of led? I want 2 to 3 relay activate by time interval one by one for controlling load.
Swagatam says
you will need a 4017 IC with IC 555 for getting a sequential switching of the relay
gio defly says
sorry, I want to make that first series but I find it difficult to get a "pot 1M" if it can be replaced with other sizes ?? if the input that want to use 12volt thanks.
Swagatam says
you can use a 680k pot, and also try other values for the 1uF capacitor for getting different flashing rates
Daniel Boulanger says
Hi,
I tried the "Light Fader Circuit Using IC 555" circuit, but that doesn't work. In fact, I only obtain a pulsing flash, no fading whatsoever. I also simulated the circuit with LTSpice and the output voltage is strictly positive therefore I don't understand nor can I figure out how the reverse biased diode can actually turn on.
Help would be appreciated.
If someone has been successful with this circuit, please confirm.
Swagatam says
Please try the second last diagram with the following modifications:
replace the 100 ohm resistor at pin3 with 470uF or any other high value capacitor with positive lead going to pin3.
remove the extra 1K situated on right side of the green LED.
now check the response.
all these diagrams were taken from EFY magazine, these are not my creations.
Daniel Boulanger says
This doesn't provide a fade-in/fade-out effect like I wanted.
Like a lot of sample projects on the net, a lot of them are just thrown away, not even tested or are lacking of essential details and/or explanations.
It would be nice to have some information as to what to expect, specially signal wise. When assembling little circuits like these, but having just a qualitative description of what the circuit should do, is not very educative. At least, have more meaningful references, would help hobbyists to pinpoint and understand the errors they may have done.
With so few components, the odds of connecting things wrongly are slim to none. Having results that are way off from the author's description leads me to believe that many circuits were simply never tested before.
Not a too pleasant way to learn.
Daniel Boulanger says
Hi,
In the "Alternate Flasher Circuit" section, you have two schematics. Both of them may refer to a 470uF capacitor, as the value is written at the bottom of the schematics themselves, but the capacitor's symbol is nowhere to be found on the schematics as such. Did you omit to remove the 470uF marks or simply forgot to put the capacitor symbol in place ?
I can understand that this could be some substantial work, but it would be great to see the circuits you're proposing in action on Youtube. Just by looking at the video clip we would know right up front if the achieved effect is the one we're looking for and if so, gather the necessary parts and get the job done.
Happy New Year.
Swagatam says
yes, it seems I just forgot to erase the 470uF from those diagrams.
Even I am interested to make You tube videos for this site but that looks impossible at the moment due to the huge amount comments that I receive everyday and have to answer them throughout the day, which leaves no spare time for anything else.
wish you too a Happy New Year
Faizan Hamayun says
waiting for the reply.
Swagatam says
it's difficult.
Faizan Hamayun says
How to get flash rate of 2sec ?
Faizan Hamayun says
But i need with battery sensing when battery attached to it then it will start blinking.How can it be done?
Faizan Hamayun says
But when not connected with battery the circuit LED should not lighten up it will blinks only when battery attached to it and gets solid when battery reached to 4.2V kindly suggest.
Swagatam says
I think I have already provided this circuit to you a long time ago…
Faizan Hamayun says
Can this be modified for a lithium ion battery i-e upto 4.1v the LED flashes at rate of 2 sec and after when voltage reached to 4.2V the LED gets solid.
Swagatam says
An opamp circuit will work better
Lord of Blackspot says
Hi sir I'm new in electronics. In ur 555 circuits, I cudn't find the voltage value for some capacitors. In the parts list given, voltage values for some electrolytic capacitors (eg. Capacitor – 0.01 uF, 470 uF, 220 uF, 1 uF). So how can I define the capacitor value without voltage?
Thank u sir.
Swagatam says
The safe value is always twice that of the supply voltage….the non electrolytic caps are all manufactured with a minimum 50V rating while the electrolytic types can be selected to be twice that of the supply voltage, if it's more it won't be an issue
SHRi Ganesh says
You mean, if I'm using 12V supply for this flasher circuit, then should I use 24V rated (electrolytic) capacitor?
Swagatam says
that's right…normally all electrolytic caps are rated at 25V and above….
amit Mazumdar says
sir, i want to know why you use a pot in this circuit
amit Mazumdar says
sir i want to make a blinker circuit with three part of leds please help me
Swagatam says
for making the frequency adjustable…
Swagatam says
you can try the following circuit, just connect single LEDs in series with each of the 2.2K resistors.
https://homemade-circuits.com/2014/12/3-phase-signal-generator-using.html
Jaco Weideman says
Hi Swagatam. My name is Jaco and I am from sunny South Africa. I have an aquarium that I want to "modify" the lights on. I would like a circuit based on a cd4060 chip that can bring multiple strings of LED's from power off to max brightness and the reverse over a period of 8 – 12 hours. I'm going to use set times to explain what I would want to happen. The actual timing will obviously not be that perfect. But here goes. My basic idea – at 6am the circuit should start lighting up slowly to max brightness until 11am. It should then stay on max brightness until 1pm. Then slowly dim from max brightness to off at 5pm. It should stay off until 7am the next morning when the cycle restarts. An arduino circuit will unfortunately not work for me, as I cannot get my hands on one. Thank you in advance.
Swagatam says
Hi Jaco,
I'll try to design it and post it soon for you!
Muhammad Nafees says
Hi Genious
I need a timer circuit for home generator which have 2 variable resistors, These 2 variable resistance can control the on and off time, can set then in a way so that generator starter motor runs for 10 seconds and if engine won’t start within 10 sec then this circuit will switch it off for 4 sec and then start again for 10 sec, 3 times then the circuit turn off.
Swagatam says
Hi Muhammad,
the circuit presented in the following link is quite similar to your request:
https://homemade-circuits.com/2014/01/programmable-diesel-generator-timer.html
you can just reduce the number of sequential stages of the timers and modify it according to your needs.
jhonee aseek says
Hi
Thanks for sharing,
I have 2 LED my leds can handle 12-14,5v
About your circuits, can I used for my led?
Swagatam says
which circuit are you referring to?
jhonee aseek says
I have plan to make my leds running flipflop (one led on one led off) do you have schematic for that? hmm.. for do that should I using 2 ic 555?
Swagatam says
you can see the 5th circuit from top
Swagatam says
you can try the 5th circuit from top
Soon Chong says
Hi, Im trying to build the light fader circult you shared..but it turns out to be a LED blinking circuit..one of the LED is blinking while the other lighted up constantly.What is my mistakes?
Swagatam says
Hi, Try increasing the value of the LED series resistor to above 10K and adjust the 1M pot to get much slower flashes…these mods will ensure the desired fading effects..
Skl Dj says
hi, this is really good circuit. i need to build this circuit.previously i build led flasher by square wave generator with opamp. actually i am trying to build a led indicator that stay for very little moment and goes out for longer period( i mean not like square wave led on and off duration is same.but like a quick spike with more distance between them) hope you understand what i mean to say. could you please provide me this type of circuit…op amp is preferred. thanks
Swagatam says
Hi, for your referred application you'll probably need to build a IC 555 ramp generator as given below:
1.bp.blogspot.com/-Ay6t5Dy7UiI/VHRLomF_zaI/AAAAAAAAIoE/Www8vwHaEUI/s1600/Ramp.gif
the trigger input could be connected to the output from another 555 square wave generator.
Geoffrey Hurlbut says
Hello – not sure if my comment posted before; forgive me if this is repeat. Can you provide diagram of how you would link two 555 circuits to A) randomly switch on four separate LEDs and B) use a 555 for fading the on/off cycle when an LED is switched on? would I just use the first 555 circuit in the power supply path to the second 555?
Swagatam says
Hi, you could probably use the other 555 IC as a simple astable configuration and connect its pin3 with pin4 of the fading effect generator 555 circuit. pin4 of the fading 555 circuit must be disconnected from the positive and then connected with pin3 of the astable
a better random light generator could be made with a 4060 IC, the different outputs of the IC could be used for creating an assorted number of random effect generator and also the fading effect could be achieved through capacitors connected smartly across the LEds or the involved resistor to ground.
Geoffrey Hurlbut says
thanks for advice! I'm very rusty at my electronics – would you be able to provide a rough sketch of the 4060 set up you have described? thanks!
Swagatam says
you can make the circuit shown in the following link:
https://homemade-circuits.com/2012/01/how-to-make-simple-versatile-timer.html
remove D1, it's not required.
use pinout no. 1,2,3,4,7,1,10,14,15….for the LED connections (pinout to ground)…you'll find the leds illuminating and flashing at different random rates.
connect randomly selected capacitors between 10uF and 100uf and connect them right across the LEds to get the desired fading effect on them.
make sure to connect a 1k resistor in series with the LEDs….
Geoffrey Hurlbut says
thanks! I will give it a try!
Arun Dev says
sir i want to make an LED workinog model of the Solar planet system…do In each elliptical path of each planet LEDs should be placed indicating the po position of the planets in their path…. In each path a starting LED should be thier which starts blinking once and transfers the voltage to the next consecutive LED in that path…. means the starting LED should start blinking then is kept idel ( off state ) untill the transfered voltage comes back to it completing that elliptical path….
similiarly each orbital path should follpw this……
plz help me immediately sir
Swagatam says
Arun, but how will it simulate the solar system functioning , I could not understand this, please explain the whole sequence in detail for correct implementation of the design.
Edd Anthony Bague says
hi Swagatam,
Im making the light fader circuit using ic 555
I just would like to ask though, if it is ok for the capacitors to be interchanged with neg/positive connection, if not, which is negative and which is positive. thanks.
Swagatam says
Hi Edd, yes it would make no difference…
Hiba Saidi says
I built the first circuit! It works great,but how can I calculate the frequency at which the LED is flashing? -Thanks!
Swagatam says
Thanks! You can take the help of online 555 calculator software and calculate the various involved parameters.
Farmer Dragon says
Hi Swagatam, You blog is very helpful.. thank you making such a great site for sharing electronic ideas… My question is that I want to make LED Flasher using 1watt High power LEDs 2 or 3 Different color LEDs which can produce some random effects..
Another question is that can I use 4v Battery with this circuit?
Swagatam says
Thanks so much Farmer!
For random effect you could probably try the IC 4060, use the configuration that's shown in the following article:
https://homemade-circuits.com/2012/10/making-led-illumination-circuit-for.html
Eliminate the shown T2, T3, C2, C3 and R4, and repeat the T1 stage randomly across the other remaining outputs of the IC.
Use TIP122 for T1
4V batt can be used for the above linked application
Farmer Dragon says
Thanks for your quick reply.. So all of the remaining pins of IC can be used with a Tip122 + LED ? Do I need to Eliminate R4 as well? A diagram would be very helpful..
Swagatam says
Yes that's right, use TIP122 for all the transistors that you intend to use, you can try the outputs randomly and identify the ones that gives the most desired effects.
R4 is not required so you can remove, SW1 is also not required.
Simply use and repeat T1, R3 and the blue LED stage with the selected outputs.
If possible I'll try to update a schematic.
Farmer Dragon says
Thanks alot bro..
Mukesh says
hey i tried this circuit 4.bp.blogspot.com/-hHPYfQqo2RA/TvHQgoTZ6DI/AAAAAAAAAeE/Il07ySI-fmQ/s1600/555-5.png of yours alternative flashing circuit and it came very good. i tried connecting two 12v bulb of my bike but it didnt worked..please gie me idea to connect 12v bulb and battery 12v bike battery..also please say what component i have to change to increase the output volt and watt please…
p.s please reply to this post as i havent activated notify me on my previous comment sorry
Swagatam says
Hi, do the following steps:
buy two TIP122 transistors. remove the LEDs and the 1k resistors from the existing design at pin3 of the IC
now connect the base of one transistor to pin3 via 1k resistor, connect the base of the second TIP122 to the collector of the first TIP122 via another 1k resistor.
join the emitters of the TIP122 and connect them with ground.
now connect the two bulbs across the collector and positive of the two TIP122s, meaning one wire of the bulb will join with the collector, the other wire with the positive…
do the same with the other bulb and the other transistor.
Mukesh says
will try soon bro if i follow this i should able to glow 12v bulb ryt thankq 🙂 and will it the same for 24v?
Swagatam says
yes 12V 1amp bulbs can be illuminated, 24bulbs will also work, but the IC circuit will need to be fed through a 7812 IC so that it gets a constant 12V.
Mukesh says
hey frnd i built the above circuit without tip122 and it runs good when connected to 9v battery but if i connect the same to nokia mobile charger it blinks differently do mobile charger will produce high volt or watt than 9v battery?and what is the use of tip122??please 🙂
Swagatam says
the flashing will depend on the input voltage, amps and the load amp, if these are not calculated properly would resulty in different flash rates for diffetent supplly sources.
TIP122 is for amplifying current.
Mukesh says
thankq :))
Mukesh says
hi frnd…i saw the LDR circuit in your blog..can i use this in flashing circuit?if so should i replace the LDR with the ON/Off switch?also what resistor i need to use?
Swagatam says
Hi friend, which circuit are you referring to? please give me the link.
Mukesh says
sorry coudnt find it :PP please let me know where to place this LDR in the flashing circuit,so that it turns automatically if it is too dark..i tried to replace with the switch but the light is off in dark and light turns on when light is falling into LDR (oppositely to my need) :PP in the alternate flashing circuit…also please specify which resistor i need to use to make led glow on an 24v….
Swagatam says
disconnect pin4 of the IC from the positive line and connect it back through a 100k resistor to the positive.
now connect the LDR across pin4 and ground, this will hopefully produce the results that you want.
Swagatam says
with 24V suply you will need a 7812 IC, use this IC to supply 12V to the IC555 circuit, the LEDs will work normally
Mukesh says
thnkq 4 ur kind reply..will try the circuit with LDR for 24v today inbetween can i replace 100k into 100k pot? and will 7812 can able to manage approx29v? also please tell me best transistor than bc574. tried 2n2222 but the output is low comparatively..i am expecting an transistor to handle approx 29v and output gain shoul also be high..:)
Swagatam says
we already have a 1M pot, so the 100k resistor should be a fixed type.
BC547 is rated to handle upto 45V, so it can be used
7812 will comfortably handle 29V input, the max tolerable input not to exceed 35V
Mukesh says
thankz bro :))
Mukesh says
i tried connecting ldr as you said but one led is glowing when light falls on the ldr..if the place is dark it works normal…how to stop glowing that led too??i tried using variable resistor of 200k but no use:Pso how to connect to rectify it? and how much volt does 200k variable resistor or preset can able to withstand??
Swagatam says
Restore the pin4 connection to its previous form and use another 555 IC with the LDR as given in the last diagram of the following link:
https://homemade-circuits.com/2012/01/how-to-make-light-activated-day-night.html
In the diagram Swap R1 and LDR positions, remove the relay and connect the flasher circuit's positive to pin3 of the IC, meaning the supply to the flasher circuit will be now received from pin3 of the new 555 circuit not fr the battery.
Mukesh says
will try it soon 🙂 inbetween i am going to connect 1k pot,6 double color led 25ma 3.2v each to a 24v circuit will it works good?or i have to add some other extra?
Swagatam says
yes it will work, but not sure where will you connect the 1k pot?
Mukesh says
1k pot beween +ve of battery and bulb which is connected in series..
Swagatam says
use a 1k fixed resistor also in series with the pot for safeguarding the LEDs, i guess you are using it for dimming purpose?
Mukesh says
no i used pot to adjust the input current is it enough or to add ik? since 6*3.5 needs 21v and have to reduce 8v and resistor calculator said 460ohms so only decided to put 1k pot…shall i add 1k too? will pot becomes heat on 24hr run?
Swagatam says
if you accidentally reduce the 1k pot to zero, all your LEDs would burn that's why I suggested using a series protection resistor with the pot….
Mukesh says
serious protection what resistor i have to use? 1k or less?? i have connected led to240v via 100k resistor and works good from past 15min but what watt i have to use?1/4 or 1/2??
Mukesh says
and to your consideration the resistor gets heat up during the process as soon it is removed from the current supply it gets cooled within seconds. i hope it is 1/4w resistor…please help me to decide between 1/4 or 1/2 watt..i connected red led and it was glowing dull what resistor to replace to increase the current?i tried connecting multicolored led it is glowing only two color :PP please help bro 🙂
Swagatam says
you said you were using it with a battery, not sure what exactly you are up to. you can try a 22k, 5 watt resistor for max brightness
for AC mains operation ideally you can try the circuit shown in the following article:
https://homemade-circuits.com/2011/12/cheap-yet-useful-transformerless-power.html
use 0.22uF/400V for C1, don't use the shown 105/400V.
Mukesh says
let me be clear..u said that to use 1k in series with 6led for safety i have used 1k pot already and i am asking is it necessary to add 1k? i installed in my vehicle and works good….
2. experiment 2 : i tried connecting a led with 100k into main current supply A/C ie to 240v electricity but the brightness is less for red color and tried blue it is glowing very very lightly..so wt resistor i have to use ?i used 12k resistor stated to smoke :PP
and sorry for confusion 😛
Swagatam says
OK…
anyway, I have replied to both of these questions in the previous comments….pls read them carefully.
you can use a 1k resistor in series with the pot or a smaller value such as 470 ohms. why its necessary is already explained in the previous comments.
Mukesh says
ok bro thankz 🙂 22k 5w glows led only for few seconds and begins to smoke..will try 70k resistor instead..
Swagatam says
if it was 5watt rated it shouldn't have smoked. anyway you try higher values
Mukesh says
yeah only red color works charm and green glows dimmer..if i use dual color(red green) led only red is glowing constantly without green why??the same result for 69k,100k,120k very little difference for these three..i used 1/2 wt now…
for previous comment sorry not 5 watt its 1/4 it started to turn black and i removed it at once..
your awesome man 🙂 lot of thankz to your patient with me and helping me exploring electronics 🙂
Swagatam says
thanks:) use 22k 5 watt and it'll solve all the mentioned problems:)
Sriram Kp says
In the first circuit, can I use 33k instead of 22k??
Swagatam says
yes can be used
dim tim says
evening, just tried to make the Police Revolving Light Effect, but no luck. if I disconnect pin 1 the led will power up and the discharge slowly when the battery unplugged. any idea what I done incorrectly.
thanks
Tim
Swagatam says
the circuit should produce a fading effect initially basically, can you tell me what are you expecting the effect to be, because there are number of different ways of implementing a particular desired feature
Ethelethoh says
Hi Mr. Swag,
I want to build a flasher with about 200 LEDs using 9 volts or 6 volts transformer, the circuit I built with 555 IC was not able to power the LEDs.
Please help out with a circuit digram or instruction on how to go with this project.
Thank you.
Swagatam says
Hi Mr. Ethelethoh,
Please refer to the first diagram in the following link, see how the leds are wired up. You can connect as many led strings you want in the shown manner. The resistor will need to be calculated appropriately depending on the wattage of the LEds:
https://homemade-circuits.com/2012/10/automatic-40-watt-led-solar-street_2.html
nayaBapu?? says
I was wondering what is the circuit used by multi mode led trail light designers. It's it possible to change the rate of blinking, enabling constant on, etc by pressing the same button more than once. I've thought about it but am not able to understand how they make it.
Swagatam says
it will require a microprocessor, cannot be done using ordinary ICs.
Anonymous says
Hi sir i want flasher ciruit to make the flashing like the ones it is made in F1 racing cars at back .I want to use it for my car anyboddy can help?
Swagatam says
show me the video link…
Shreyas Patil says
www.youtube.com/watch?v=J964lGezvMk and are www.youtube.com/watch?v=HKaHRosvm80 are the videos in the second link from 0.15 to 0.20 sec and 0.35 to 0.39 sec are the required speed variations and the power of the red leds must be great ……..like the one you have used it for knight rider project of yours.
Thanks ,
2308cars.
Swagatam says
It looks like a strobe light kind of circuit, you can try the following circuit…….use high bright RED LEDs for all the channels shown:
https://homemade-circuits.com/2011/12/simple-yet-effective-led-strobe-light.html
Shreyas Patil says
Sir ,
I want the effect like stobe not chasing one .this video will help you out more in the given below video the flasher blinking rate desired is from 0,01 sec to 0.06 sec in the video .
: m.youtube.com/watch?v=JhoxkxbRZXo
Thanks ,
2308cars
Swagatam says
Hi Shreyas,
You can try the first circuit on this page, replace the 1M pot with a fixed 1M resistor, remove the 100k resistor and replace the 22k resistor with a 22k pot.
First confirm with a single led as given, by the varying the 22k pot, and if it satisfies your requirement you can increase the number of LEDs as desired.
Anonymous says
Hi swagatam
I am a beginner in electronics can the above circuit be used to make Diwali lights and can it be used with 12 voltage input and tell me the basic diff betn the chaser circuit in your blog and the one above?
Swagatam says
The above circuits will only blink a single LED ON/OFF, while a chaser circuit will create a running effect over 10 separate LEDs connected at the relevant IC outputs, that's the difference.
JaGdIsH MiShRa says
Hi swagatam bro….i saw ur blogs….i need ue help to do a bus running light by using around 300 led….how i make that ……plz help me…….
Swagatam says
Hi Jagdish,
Can you pls provide some more details about the requirement.
Hugo says
Hi, I wonder if the 555 would work with a 3.7v battery. I want a few leds in my son's helmet, and it would be nice feed them with an old cell phone battery. Thank you!
Swagatam says
The minimum operating voltage for 555 IC is 4.5V, so I am afraid it wouldn't work. You can try any one of the designs given in the link below, it would give you the intended results. You can replace the pots with some fixed value resistors, and use LEDs on both the arms of the transistor collector.
https://homemade-circuits.com/2012/01/how-to-make-any-light-strobe-light.html
vivian richard says
sir i want to know about running light with slow glow ,what type of circuit can use
Swagatam says
with LEDs or bulbs?
Abu-Hafss says
Hi Swagatam
I have found a transistor-based flasher including a relay. I have transformed the schematic into LT Spice. You can find the files below:
https://dl.dropboxusercontent.com/u/20969135/Flasher%20-%20SOGO.png
https://dl.dropboxusercontent.com/u/20969135/Flasher%20-%20SOGO.asc
PLEASE NOTE, THE POLARITY OF C2 IS REVERSED ON THE PCB BUT THE LT-SPICE SOFTWARE IS APPLYING POLARITY AS SHOWN.
Physically, the circuit oscillates when a Load is connected across the pin "C" of the relay and earth. If the load is less than 100 Ohms the oscillation is significantly fast. And if the load is say about 1K the frequency is normal.
However, I could not understand the circuit nor it is simulating in LT Spice. Could you please explain me how the circuit is sensing the change in resistance of the load. And could you please make the simulation work.
Swagatam says
Hi Abu-Hafss,
I couldn't understand how the load would operate because it's connected via a 56k resistor? The load here is obviously a relay, which would never operate at the shown position.
Abu-Hafss says
Hi Sawagatam
First of all, I hope you have understood my Spice model of the 5-pin relay. Pin A and B corresponds to the coil of relay. Pin D is 'NO', pin E is 'NC' and pin C is the switching pin.
The (+) ve rail and the collector of Q2 energizes the relay coil which switches pin C from E to D, i.e. Pin C is switched to +12v which ultimately switches ON the load lamps.
At this point, I assume some signal is also feeded back to the base of Q1 thru 56k resistor which controls the frequency. As mentioned in previous post, following is the behavior of the circuit:
a) No load between pin C and (-) ve, no oscillation.
b) Low resistance load, faster oscillation.
c) High resistance load, slower oscillation.
I have already replicated and tested, it is working fine but, cannot understand how it is working.
I intend to incorporate similar sensing system in a 555+relay-based flasher.
Swagatam says
Hi Abu-Hafss,
Theoretically your assumption looks perfect to me. Did you test it practically? Because nothing can be more precise than testing a circuit practically.
Actually I never rely on simulators, I prefer doing them in mind…
Abu-Hafss says
Guru jee
You can do it in mind but, for hobbyist like me also work on simulator.
I have already mentioned, I have tested it practically and it is working fine. But I want to dig out the portion which is sensing the load resistance and want to incorporate in 555 based circuit.
Swagatam says
If you could show me the entire schematic or provide me with the original link, it would help me to understand it better.
Abu-Hafss says
Hi Sqagatam
I have the original unit with me. I worked out the schematic and have already provided the link to it. Nothing is missed, I have also tested the circuit on testboard following that schematic. If you want I can get you photos.
Swagatam says
OK Abu-Hafss, please send me the images if it's possible, I'll write a new post about it and publish it with the given details….I'll redraw the schematic with everything in it's position like the relay, the lamps, the sensing lamp, the switch etc.
Abu-Hafss says
Hi Sawagatam
Please follow the links below for the photos.
https://dl.dropboxusercontent.com/u/20969135/Circuit%20-%20A.jpg
https://dl.dropboxusercontent.com/u/20969135/Circuit%20-%20B.gif
https://dl.dropboxusercontent.com/u/20969135/Swagatam.doc
Swagatam says
Hi Abu-Hafss,
Thanks! that's indeed a great effort, you have done everything very neatly.
I'll update it soon in my blog with all the details that you have provided.
Abu-Hafss says
Hi Sawagatam
I think you deserve it, you are also helping others.
Ah yes, I am sure the following link might be helpful:
nls.net/mp/volks/htm/3-term.htm
Swagatam says
Thanks Abu-Hafss,
By the way I have published the required article here:
https://homemade-circuits.com/2013/05/car-turn-signal-flasher-circuit-with.html
Abu-Hafss says
Hi Swagatam
I have built a car flashers with:
a) 555 (astable mode) + relay
b) NPN + PNP + relay
Both are working fine. However, I need to understand one point.
Normally, a car has 3 indicator lamps on each side. When installed with original flasher unit, if any of the lamps fails; the flashing rate is almost doubled. Is it possible to include such LAMP OUTAGE DETECTING circuit in my flasher circuits?
Swagatam says
Hi Abu-Hafss
with a relay in the middle it would be difficult to add a detection stage, because the relay completely isolates the lamps from the flasher circuit.
It would be possible if a transistor or a mosfet is used in place of the relay.
Swagatam says
Hi Abu-Hafss,
With a relay in the middle it would be difficult to add a sensing stage because the relay contacts completely isolate the load from the circuit.
If a mosfet or a transistor is used in place of the relay then it would be possible to detect the lamp situation through an LED or another small lamp.
Abu-Hafss says
Hi Sawagatam
Can you please give me an ideal circuit for detection stage, I can replace the relay with mosfet. Thanks for the help.
Swagatam says
Hi Abu-Haffs,
Actually the idea can be implemented even with a relay circuit. You just have to include a low value resistor in series with each individual flasher bulb wires, it may be introduced in series with the negative line that goes to the bulb or the wire which comes from the relay to the bulb.
Across these resistors an LED may be wired via a series 100 ohm resistor.
Now whenever the bulb flashes the LED will also flash, in the absence or fusing of any of the particular bulb, the relevant LEd will simply shut off, providing the required warning
Vaibhao Ingle says
hi sir in alternate blinking circuit can i connect 12 led. if yes. then i want each led glow for 3sec. then off then second one glow for 3sec then off. then third one glow for 3 second like this.
Swagatam says
Hi Viabhav,
You will have to make a chaser circuit for achieving this effect, the above circuits will only produce alternate LED blinking effects.
wapcrppr says
Hello Sir, I'm interested in the alternate blinking circuit. How would I go about placing 4 or 6 breadboards with 8 LED's on each one. I know how to get the resistor values for the LED arrays, just would like to know how to connect them, thank you.
Swagatam says
If the supply is 12v, you can connect 4 red leds or green leds in series. Make more strings of 4 leds and just connect them in parallel in order to increase the numbers.
Anonymous says
sir,,i want to add led up to 100 to 150? what resistor needs to do this job thankz
Swagatam says
Only up to 30 LEDs will work with the above circuits, not more than that….
Anonymous says
Sir myself Adithya.Since last month i have started making basic circuits in my home.To do more interesting and complicated circuits specially on ics which book i have refer for and what are all the basic instruments that i have to buy and alternatives to osilloscope for i cannot buy them by paying huge amount.
Swagatam says
Adithya, if you are having an internet connection and a computer at home you wouldn't need to refer any book….online is the best source to learn electronics.
fundamentally you would require the following devices:
a 25 watt soldering iron
a 0-24V, 0-5amp variable power supply unit.
a dugital multimeter having ranges for measuring ACV/DCV, Amp, Ohms, diode, frequency, capacitance, inductance.
a breadboard or a bunch of veroboards.
parts and accessories as per preferences and needs.