How to Control the Duty Cycle of a 555 Timer
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- เผยแพร่เมื่อ 28 พ.ค. 2024
- Control the Duty Cycle of a 555 timer with just a couple of diodes. We'll look at this circuit in general and then look at an application as it applies to a DC motor.
Webpage for Schematic: skinnyrd.com/how-to-control-th...
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Thanks once again, another great tutorial putting me that much closer to understanding choreography that exists between the 555 timer and the other components. I'm a novice and though I've always had a fascination about microelectronics and how they worked (for well over 50 years).
I was able to purchase a Signal Function Generator and a basic Oscilloscope recently. This boosted my understanding and really revived my interest in this field (strictly as a hobby for me). I coupled the scope and generator with very good tutorials such as yours, and I think I've probably learned more in the last 1.5 months, than I have in any 10 years of the time I spent teaching myself using trial and failure techniques.
I have noticed that you don't seem to note the size of the capacitors (and a few other components), in some of your videos. Perhaps, if you just flashed a list of the components that you used in the tutorial at the end of each video for 2 seconds? Maybe just for the smaller, simpler tutorial videos, (I have no idea how much trouble that would be, so I understand if it's not practical).
Thanks again,
Rich
Great video, just the right amount of technical detail and very clear explanation. Thanks
Another great video. Can't wait for more. I'm getting a lot from the explanations, your examples are clear and using the paper bag to draw out the circuits makes it all the more clear.
+Terry Burns-Dyson Glad you enjoyed it. We are always given paper bags at the grocery store but always forget to take them back to the store to reuse them. The result is we have a pile of bags. I consider them a form of active recycling :o)
A very clearly, well explained tutorial video. Exactly what I'm looking for to fine speed control a motor driven astrophotography camera mount. Thank you.
Jason, I am enjoying your videos! You are one of the best teachers I have seen! You make understanding electronics fun and easy, keep up the great work and thanks for devoting your time to do this!
Thanks for watching!
Jason, I recently found you and, I think you're great to do these tutorials and lessons. THANK YOU, Jason! 🙋🏻 - sarah
Thanks! It's my pleasure.
Bravo! Every time I learn something with this hobby, for once again I am thinking why I didn't think before that trick with the diodes? Until today I thought that 555 timer is capable only for 50% -100% duty cycle and I was reversing that by using an NPN at the output as inverter logic gate.
Congratulations Jason!! You are a very good teacher. Thanks for helping us that want to learn. Cheers :-)
I think you have a gift for teaching. Excellent.
Brilliant teaching - thank you. Love the bits of card and paper bag :)
I'm glad I found your channel! I really enjoy your videos
thanks!
Wow. The very best 555-Timer Howto I found so far. Very good explaination, very nice done with the drawing and Breadboard. Thumbs up & subscripe
I'm really glad you don't use 'engineering' terms. Your video's are so much easier to understand. I will be signing up for newsletter and downloading the schematic. Thanks you for your tutorials
Your welcome! I don't use many "engineering" terms because I'm an idiot. I have to put things in simple terms just so I can understand it.
You like to teach and you are good at it...thanks!
Good explanation, very useful. Thanks admin......keep it up
You are awesome. Your videos help me a lot. Thank you bro..
Thank you so much for your videos, I made a simple circuit with an LED and did not connect pin 4 to Vcc but it still worked? But it was very low frequency!! I mean on for a few seconds then off for a few etc. Still at least I know more about the 555 timer now!
well done, great way to explain
seconded... good video! not too basic, not too confusing. easy to follow!
+Kelvin Mead Thanks! I'm glad it came across clearly.
Big thanks for your videos. BTW if u take both R1 and R2 as a variable resistor you will be able to control both on and off pulses at least this happens in simulator, so you can control the duty cycle from 0 to 100 percent almost.
this guy has just 10k subs? make him famous for all the work guys please
thanks man!, I was figuring out a way to control a toy motor with a 555 timer just like you did, but I'm also trying to change its direction with an H bridge and a switch, but I had troubles varying the duty cycle so thanks now thats done
Glad you found the video helpful!
Great video thanks!
Now I have a better understanding of the way it works, do you know of any links to help me with calculating which resistors and caps to get certain duty cycles?
I'm trying to build an Led strobe so it lights for around 2ms, with approx 10ms cycle (100hz). the idea is to monitor rpm of a spinning disc. Any tips would be appreciated!
nice explanation. how would you change the pulse width without changing the frequency? does it require a dual-gang resistor for R1 and R2?
Your a GREAT teacher!thx for your time
Thanks for watching. Glad you liked it.
very good video, thanks a lot!do you have another video show how to create irregular pattern pulse?
Hello and thank you for your very informative videos.
I am looking for a circuit or a signal generator capable of providing a rectangular signal varying from 0V to 5V, but with a rise time of 30ns.
I want to apply this signal to the reentry of a microcontroller.
Very cordially
Hi! excellent video, thankyou very much.
I wanted to know though, what's the voltage on the output when it's on high..and how does it depend on Vcc ("power supply", on this case 9V).
I want to use it on my car, so i will use 12v as Vcc and i need 5v on the output to used for a servo signal.
awesome video bro, great explanation, please keep them coming ))
Will do. Thanks for watching!
Great video, thanks for sharing.
+WestonWood Thank for watching!
its been years and years since I last saw this type of motor... my childhood memories of opening up and examining the toys :-)
vibrator?
thank you bro for ur great video
Great teaching. One question if you still pop by here. The timing math for the 555 I guess you use ohms for the resistor and farads for the cap so when you have added them, multiplied and divided them what is the answer in?
hi!
I was wondering which npn transistor did you use?
I tried it with 2n222a but the speed doesn't seem to increase.
thank you for the video!!
Great video. Thank you
Glad it was helpful. Thanks for watching!
Great video, nice work! But, to vary the duty cycle without affecting the frequency, should I use a single pot connected in R1 and R2? I use ordinary silicon diodes or need to choose special models for high frequencies? (I want to maintain a 2 kHz working frequency)
+Enfermeiro Pensador To be completely honest, I haven't tested out how to keep the frequency steady. It's in my list of things to do. As soon as I figure it out, it will probably be a video.
Thanks. This would be an excellent addition to your channel. Certainly, not just me, but the whole community would appreciate.
+Skinny R&D
I believe this should work, but I haven't tested it:
drive.google.com/open?id=0Bxk-g3_XwgbSc285TEJVcVhwLTQ
There is an excel file here to calculate the cap you need for the given resistors Ra,Rb, potentiometer Rc (= total resistance of the pot) and frequency output. I don't know if the diodes affect the result...
can't wait to try thanks great explanation once again
+RC Canuck Thanks! Hope it helps.
Nice Vid! I'm subbed, thanks!
Thanks for the sub!
Thank you so much..
you r just awesome
Other than the isolating aspect of isolated gate drivers, is there any advantage in using a gate driver between a MOSFET and a 555?
Super sir , I need to know that how much of frequency produced by this 555 based circuit
Just viewed this video. In which you use what was known as conventional theory, ie current flow in a circuit is from positive to negative ( which only occurs in a power source, batteries, generators, etc). Whereas in circuits external to power supply, cuttent flow is from negative to positive. The symbol for the diode was created while conventional theory thought to be correct for power sources and load circuits. For a diode to conduct, negative potential is applied to the banded end and position potential to the other end of the diode. Based on these the current flows through the circuits would be opposite those describe in the video.
Hy. Thanks again for your video.... very good explication. Actually I need to do a circuit based on 555 family and i want to have a 50% duty cycle and be able to change he frequency from 30 Hz to 30 KHz. I tried some possibilities but it did not worked. so, i thought that you have an idea to do this. thanks a lot.
great video - thanks a lot. How would you change the duty cycle to an irregular pattern (eg for communication as you mentioned at the start of your video)? Now subscribed!
+cpobyrne1 Thanks for the subscribe! You can feed a varying voltage in on pin 5 and frequency modulate the output.
Nice view from the windows!
do you have a formula where I can set a specific duty cycle and frequency to find the values of r1 and r2?
Would you please explain in brief about pin 5 of the ne555 timer ic.
By this way - can It use to Desulfator batt circuit ? I mean @10% ON - coz, on another video they said 555 doesn't allowed It, Thank You, so much
A question: So If both input (of flip-flop) were zero then flip-flop will the keep that bit until next change is applied to the input, right?
by the way this video is awesome, it's very good for beginner. And the reason why this kinds of video are awesome is you'll need a simple term to explain the complex stuff. and it's always hard to find the right terms.
hi..thanks for tutorials,uts really helpful, please show how to convert square wave output of 555 into sine wave.☺
I needed a 1uF capacitor bridging CVV to GND to prevent overshooting at the start of the cycle. With a 12V input,
max voltage was 20V.
In this setup, is it required that 6 and 7 be connected.
initially when the supply is given from pin 8 and the current starts flowing towards the capacitor through the diode,but won't the current pass through the transistor and then to the ground at pin 7?
Can you tell us how a NE555 with an Operational Amplifier as a comparator where it can be used to Modify PW as a quick and dirty solution for PFC of an offline SMPS? That would be awesome! I've been making astables with BJT's, but I just got some NE555s, and you brought it to my attention in a previous video that if you supply a voltage to one of the pins, it will modify the PW. Of course I'm driving the MOSFET with an NPN-PNP common emitter configuration. There doesn't seem to be a complete tutorial on offline SMPS Topology. Your'e a good professor and I( I believe I can speak for others based on what I've seen posted on various videos) would like to see a playlist on the topic, if it interests you of course. The Post Apocalyptic Inventor came the closest in completing a detailed tutorial playlist on Switch Mode Power Supplies.
I'm not sure I can, but I'll add it to the list and see if there's something I can do with it.
I just completed this configuration and this is version 4 or 5 at this point. I've been at this for apx. 1 year. I've been trying to get control of a fuel injector's duty cycle. All I ever get is 50% duty cycle. I just rebuilt the entire circuit again, I did it exactly like you have in your diagram & I can remove the caps & its apx. 50 percent duty cycle (caps are removed at its 50% duty cycle). I can never get the injector to open for 1/10th the time it is closed. Am I the only person who has built your circuits? Everyone likes your circuits but nobody has attempted to make one.
Just removed everything, its flashing at a constant rate without the 555 in the board.. lol
What if I want to power it with 4.5v should caps and resistors changed?
such goodness!
Hello! I am not sure why you have connected 9V to the pin 4 of the 555Timer. Is it because you can disable the Master Reset through this way? As in, that's a PNP transistor, and if you put 9V to the base of it, it will be in cut-off mode?
Based on a quick internet search on the 555 timer, Pin 4 is the RESET pin which can be used to restart the 555’s timing operation. Like the trigger input, reset is an active low input. So pin 4 must be connected to the supply voltage for the 555 timer to operate. If pin 4 is momentarily grounded, the 555 timer’s operation is interrupted and won’t start again until it’s triggered again via pin 2.
Listen to Andy.
I got it! If Pin 4 is not put to the power supply, then the timer will shut itself off right after being activated via Pin 2, so no continuous operation. Thank you!
Have you try to get to 50 or 60hz with 555 timer I try every valve there is and I still couldn’t get 50 or 60 only 107hz so if you could figure it out on video that would be good cause there is not a violation on TH-cam about this to inverter with
Hi sir, I've done this tutorial using LEDs so now I can control whether it'll blink slow or fast. I'd like to ask for your suggestion as to how I can manage to have a blinking LEDs to switch manually to a steady on state. I'd like to have an outcome where I can manually switch my LEDs to OFF, ON and blinking state.
By the way, your tutorials are great. :)
Well,nice video but i suggest you to use this circuit of 555 timer which has adjustable frequency (PPM signal) to control a stepper motor's velocity(each pulse->steps the motor.....pulse rate->motors velocity).Now there is an another circuit works with 555 timer which produces stable frequency signal with variable on-off time of the signal(PWM signal),so the second one can control a dc motor (pwm controls the applied voltage and and dc motor speed is proportional to the voltage).Make a video of that!
Thq soomuch..❤
What would happen if instead of this setup you had a potentiometer between pins 6&8 with the slider to pin 7?
How will it work by puting 3 pin pot,midle pin on the diode - end,so when you turn pot fully one side you get one big and one small resistance?
+ivic1112 No.I see the diode is problem
hello can anyone help me i need circuit 1-100hz with independently adjustable duty cycle to control fuel injector.any ideas?
can i control 1 rgb led with only 1 555 to create different colors?
can u give me some advice on using the 555 ic to control a cd4017be ic to switch the output on it thanks
I'm not sure what you want to do but you can push the output of a 555 timer into the clock input for that chip.
11:54 I was saying to myself, "that scope should be able to display the duty cycle". Then he enabled it. 🙂
Is the wave completely positive?
Nice video!
Can you follow up on how to control the duty cycle with a voltage?
I want to PWM a PC fan attached to heatsink, and vary the duty cycle according to the voltage from a temperature sensor.
After quite some Googleing found 2 555 solutions. One uses 2x 555s (or one 556) and pin5 magic. The other uses a 555 to create a triangular wave and a comparator for the PWM.
I can dig up the links from my notes if you are interested.
+Álvaro M. Valdebenito B. Thanks! I'm always interested in fun projects. Feel free to add the links in comments.
Skinny R&D Here is the ref for the 555 & 393 PWM (Chapter 5: The and PWM)
forum.allaboutcircuits.com/threads/leds-555s-flashers-and-light-chasers.19075/#post-117641
Skinny R&D Cound not find my original refreence. Thaks to google found anither one. the control voltage goes to pin5 of the monostable 555:
www.learnabout-electronics.org/Oscillators/osc46.php
how can i use ic 555 circuit as power on/off circuit for application such as night lamp. if i have to switch on lamp every night for 8 hours and switch off it after that....
can i use ic 555 for such a long duty cycle
My newest video is about using the 555 timer in monostable mode. That circuit has the functionality you want, but the components, a resistor and capacitor, would need to be quite large to achieve the time you are looking for. I'll put this on my list and give it a thought or two.
Hi, I have made a monostable multivibrator using 555NE timer ic. What observing is it is getting triggered automatically when some electrical appliances are being switched on or off in the house. So is the 555NE prone to pickup noise or problem is something else. Can you think about it plz if you get time.
What are you using as a power source for the circuit?
Skinny R&D If using 9 volt battery to power the timer circuit & pin 3 is connected to ground through a resistor & optoisolator, In the other side of opto isolator ( moc3041 ) bt136 to switching 240 volt 1 Amp universal motor is used. Same problem is coming .
Is the mains ground at any point connected to the battery ground?
Skinny R&D No Sir, only possible physical connection through opto isolator. But same circuit using same component working properly in breadboard, but we have printed a circuit board where this problem is coming.
Are you using decoupling capacitors on both sides of the opto isolator?
can you control duty is not relation frequency?
Question: When pin 3 (output) goes low, would that turn on a pnp transistor and when it goes high it would turn on a npn transistor?
Btw, subscribed.
Yes, it will. I use an NPN halfway through this video: th-cam.com/video/dukZlsRoCJo/w-d-xo.html
Thanks for the sub!
If you are using motors or other devices that create inductance you should be advising the use of flyback diodes across the motor. This is probably why you had heat.
Hello, Great videos. All the videos are great. I teach physics and some of my students are working with wildlife biologists to shock fish so they can tag them and when they wake up, let them go. The fish never get hurt. I am trying to advise them on making the device. My hobby is electronics. My plan is to create a voltage source (0-40V) with variable dc pulsed voltage, duty cycle, and frequency. I am using the mains voltage (AC 110V) , (fish are in a tank for testing) and stepping it down to 40 Volts. I am trying to find a ways to vary that voltage and display it. I think I will use voltage regulator LM317 (only max 40 V) and a panel meter to display voltage. I plan is to use a 555 time like in this video to vary the duty cycle and frequency and an IRF510 MOSFET to pulse the voltage from the 555 timer. Am I on the right track? Any suggestions? Thanks! Curtis.
Sounds like a fun project. Just make sure you use a MOSFET that can handle the current draw you predict.
Curtis, Could you use a fence charger for shocking the fish? Fence chargers are readily available and can be low cost. May have to tame it down. Tom
Thanks, I'll research that. I also looked into boost converters, the only transformer I have is 1 amp and 120v to 12.6v. The boost converter I got online is 4 amps output. I'll do more experimentation. I did use the 555 timer circuit on this video to have a variable duty cycles and I used Arduino and an LCD to display frequency and duty cycles. I am almost there except find the right transformer.
Hello, with this method, can i achieve a tiny duty cycle by putting R1
What capacitor would you use? The 555 timer has limitations based on how quickly it can transition and supply an output.
Thank u
You're welcome.
Forgive me but i read your channel name Skinny D, after some time i noticed R &d
I want a pwm signal of 200khz. Is it possible to get it using IC555 timer? Can u suggest any other way plz?
they're generally good up to about 500khz at a minimum. it varies depending on manufacturer and model. some can do higher current but have slower switching speed, some switch faster but have lower current limits, etc etc. you can get 500khz out of the vast majority of them tho.
How to make low duty cycle ramp signal?
what is C2 for?
how i count vale of all components.
which diode are these D1 D2
The diodes D1 and D2 can be 1n4148.
You might need a whiteboard.
Good vid!
+chbrules I like the bag thingy! It's his thing, don't make hum use a whiteboard like everybody else! :D
I agree with Scyth...its his thing and I like it very much! Keep the bag! No whiteboard!
I love the paper bag thing too :) a use other than bookcovers...
So long as he keeps using production-quality paper bags. I'd hate to see it on some low quality plastic bag. That'd be a deal breaker.
Me again sorry I've been reading a lot and finding out that Hobby Servo's need to be controlled by PPM not PWM as pwm can harm the motor or speed controller . I'm trying to control the speed of a 9 gram RC servo for an airplane to slow down the movement of the landing gear . Any ideas or suggestions would be excellent
+RC Canuck I'm not much of an RC guy but it looks like PPM is used for communications and PWM is used for speed control applications. From what I've read, PPM is used while sending controls from the transmitter to the receiver, but PWM is used to control the actual mechanism. This webpage (www.endurance-rc.com/ppmtut.php) does an ok job of talking about PWM but it's splits up the applications used for each modulation type down at the bottom. If you're looking for speed control for the motor, I believe you want PWM. You are right that PWM could harm the speed controller, because the controller is looking for a definite PPM digital command from the transmitter. However, unless the motor has some sort of built in PPM translation circuit, you would want PWM to vary the speed. Of course all of this is 20 minutes of me reading on the Internet and not having ever touched an RC control circuit. It's likely you have a far better grasp than myself. Good luck!
+Skinny R&D
thanks Jason.
I'll try not to bug you anymore
+camaro z Feel free anytime. It's not at all a bother. I learn a lot looking up things like this.
Skinny R&D cegrhrbrhe rvt r. r
Need not forget the counter EMF flyback diode in parallel with the motor.
Your explanation is good, but visual illustration should be made much bigger to be easily seen and that viewers could easily follow what you explain. But still it is a good job!
Better than my teacher. Thanks for saving my bacon.
Thanks! It's one of the reasons I started making videos in the first place. I had too many experiences like that when I was in school.
What is the value of capacitor in uf and volt??
Here's the entire schematic: skinnyrd.com/wp-content/uploads/2015/11/555-Timer-Duty-Cycle-Variation.pdf
I want t1 to be 1 hz using a 100 uf cap how do I find out the resistor
There formula to determine your answer is:
t1=0.693(Ra+Rb)C
In order to accomplish your goal, you'll need to choose a value for either Ra or Rb and calculate the remaining value based on the criteria you imposed in your comment.
wow
I have been struggling with a PWM, a 555 timer & have burned up several 555 units. I think you are answering many of my questions. I've known about the transistor, but the transistor should be supplying the power independently of the 555... many horrible TH-cam videos I've been following and all they do is get you into days & days of wasted time.
how do i change the direction of a servo motor
You would need to switch the leads or add some more circuitry.
What is the formula for frequency?
Does the dividend have a "C" or "2C"?
+Matthew Ferrie In this scenario the formula would be: freq = 1.44 / (C1(R1+R2))
how about to get a sinusoidal wave out of it?
+Eduardo Caetano I don't know how to get a sinusoid directly out of a 555 timer. In fact, I don't know if it can be done. After the 555 timer spits out the square wave, there are things you can do then. I've gotten something close by running it through about 2 to 3 transformers but I'm sure there's a better way.
+Skinny R&D
Thank you very much for the answer.
I will try it with some RC/LC/LR filters and then try to feed this signal on a next stage of a 555, dont know if it will gonna work, probably i have to calculate the (Ra and Rb)times C in function of the new "Vcc"... just a quik theory.... need to sit down and try to modulate the square wave until i get a sine.
maybe can be use a Allpass filter in a NE5532 too.
Again, just some randon ideas.
I do not know anything about electronics but it seems to me you could use a trimmer potentiometer
to play around with different values and view on a scope. I am sure they sell this as a unit but have no idea what it is called.. I guess it would be called a variable signal generator.
Read more www.resistorguide.com/trimpot/
Great vedio. But needs lettle electric background for sure
Thanks
FYI You were getting the jumpiness of the motor due to too slow of a pulse frequency. If you used something more like 500 hertz you would not have the motor jumping like it was.
Thanks for the insight!
Not strictly correct as far as I could see. PWM maintains the same frequency, only the pulse width changed. Your example appeared to change frequency.
I have not checked out the circuit to verify this.
Yes, you are correct. It is changing frequency. It's not a 100% solution but it gets the job done.
Perhaps the answer is to vary both the charge and discharge resistor values together with a ganged pot. For the control of motors it may not be a big deal if the frequency is changed but for other applications where charge control is required then it may be. I was thinking of a circuit where a MOSFET drives/switches through an inductor to a load to control a current and voltage.
It was an interesting simple circuit though.
I really cannot understand why are you stressing on the fact to use a transistor. How will a component burn up? Please explain.
The 555 chip is not capable of supplying enough current for a heavy duty motor. Therefore you need to use a transistor as a current buffer device. The transistor will be used in switch mode and switched on and off by the voltage from the 555 output. Hope this helps.
Berny M thanks a lot. it will really help me in my future projects.