Adjust the Duty Cycle of the 555 Timer without Changing the Frequency
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- Опубликовано: 19 июн 2024
- This video describes how to adjust the duty cycle of the 555 timer without changing the frequency. For schematics and formulas go here:
skinnyrd.com/adjust-the-duty-c... 
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Dear Skiny R&D, this is the best video on the internet, I am a DIY person that likes to mess around with the 555 timer. The more I watch your videos the interested I become in electronics. Thank you kindly for the help. Have a great day...
Man, I love the 555 timer and your explanations of the current flow and the math around the 555 really do make it just a bit more awesome!
Very helpful information. Being able to adjust the duty cycle makes the 555 all the more valuable. Thanks much.
Thank you SO MUCH! I have been looking for exactly this for about two days. There are other explanations, and attempts to do this, but they are all way to worried about achieving 0-100% duty cycle, and they either don't work(when I have tried them), or are too complicated for me. Also, you bothered to take the time to go through and actually explain, in an intelligible and concise manner, what each part in your diagram is doing. A+++, subscribed.
Excellent tut, Jason!!! The best and probably the most "turnable/versatile" and most stable PWM CKT of the three basic 555 timer PMW generators I've seen out here so far. This particular configuration of R1 and R2 at 10 K is exactly what I was looking for. I'm going to take this circuit and modify it to drive a 180deg servo motor between 0 and 10 degrees (that's the requirement). I'm def going to use the schottky diode for a cooler temperature circuit and better overall efficiency. Thank you so much!!
Great to see you’ve not deserted us. Thank you for these videos, makes me feel the need to get scope out.
Dust it off and get to work! :)
Very thorough and easy to understand explanation - I subscribed to your channel about a year ago after watching your previous 555 videos. Great to see you back, keep up the good work - it is appreciated! Bruce.
Thanks Bruce!
Very good explanation of the pulse duty cycle while keep the PRR constant.
Awesome, thank you so much! Best explanation of this circuit I've seen, you just got my subscription. I'll build this version. For those who, like me, prefer algebraic expressions for analysis, you can show the theoretical invariance of the frequency like so (all the credit is yours, I just reformulated some of your expressions):
Rx = Pot R (pin 1 to pin 2)
Ry = Pot R (pin 2 to pin 3)
Pot = Rx+Ry
t1 = ln(2)*(R1+Rx)*C1
t2 = ln(2)*(R2+Ry)*C1
T = t1+t2 = ln(2)*C1*(R1+R2+Rx+Ry)
T = ln(2)*C1*(R1+R2+Pot)
f = 1/T = 1/(ln(2)*C1*(R1+R2+Pot))
Yes - this is the best explanation after days of searching. I find most people shy away from the math, but you need the math to actually understand what is happening.
Very clearly explained. Thank you. I am going to try to adapt this to control a servo motor. I intend to use two MOSFETs to swap two fixed sets of resistors to give two fixed duty cycles as the servo motor employs two duty cycles, one for forward, the other or reverse.
Awesome tutorial. I've learnt so much from your 555 videos. :)
This video is by far the best tutorial I've seen. Very well explained, very clear. Keep up the good work.
Thanks! Glad you enjoyed it.
It's really a nice piece of smart work and also very well explained. Thanks a lot.
I really liked this video it help me so much in understanding the duty cycle of the waveform. So simple to understand you described it perfectly. Fantastic tutorial. Your a real champion. I am going to mark you down in my book marks in goolge should i need to ask you a future question. Cheers.
Hi Jason. Thank you very much for your great, clear and informative vids. I think they are the best on the web on this subject.
Thanks Roland!
Method of teaching was good & honestly helpful.
It's was almost a year ago when i had first watched your content on working of 555 in astable mode.
Today after having some experience in electronics i was wondering how could you use a 555 to vary duty cycle without altering frequency and that's when i found you again.
Hands down your content on the working of 555 is the best out there.
Thank you so much !!!!!!
Wondering how to to same, but with a feedback voltage instead of potentiometer
This really is an outstanding tutorial. The careful explanation of current flow is extremely helpful. Clearly you really care about exposition, so as an electronics learner it was a very easy decision to subscribe.
I have a question about the frequency variation. Is that due to mismatching of the diode characteristics? (voltage drop) and could be reduced by matching the diodes?
Loved your way of breaking it down Skinny, totaly Favored, Liked and Subbed.
Excellent explanation, thanks for the video.
Great, simple, stable, and effective circuit.... 👌
Amazing video and such a clear explanation.
Almost 15mins & I enjoyed whole minutes in your video - loved it
Thanks!
Excellent video. Thank you
Thank you for your video , it’s all about those brushless dc motors, and controlling those ESC with a variable duty cycle , I’ll get it with your help , thanks agsim
Finally someone how can explain what’s happen precisely while making a PWM. Thanks a lot for your video.
Thanks for watching!
Great explaining of the 555!
Thanks.
Thanks for watching!
Superb explanation I like it.
Excellent tutorial...
Love the video as it is EXACTLY what I am trying to do. Unfortunately, I set it up and the results were not as expected. I don't have a potentiometer, yet, so I tested with 2 equally sized resistors and just tried to get the on and off times fairly equal. My C1 is a massive 2200uF as I need the total cycle to be about 10 minutes. R1 and R2 = 47k. In the future I will employ a 300k pot. For now I'm using two 150K resistors. My calculations (using your formulas) say the cycle should be 10 minutes, but it ends up being closer to 20.
Lovely video, I was wondering could this be done with pin 5.
Thanks for your beautiful explanation. Is there any way to vary the frequency keeping a fixed duty cycle?
Thanks again!!
Very nice video, I have not seen one like it. Great job, I will be back, and thank you.
awesome video. explained it all very well. Mean this is the nicest way but the t1 calculation is slightly off, I get 34.1 micro seconds which then gives a total frequency of 25.1kHz (using all 3 significant figures as you have). Still well within the range of a PWM frequency needed for say a fan signal.
It is great to see you back. Last week was playing around with 4 other variations of the 2 diodes + pot PWM circuit. Yours is the Most straightforward and easy to understand. Thank you for that!
Something I found while playing with the different PWM circuits was that the type of capacitor made a large difference on the frequency, ie mylar/film box/ceramic caps of the same capacity gave me very different frequencies. Maybe my cheap caps are too cheap. Do you have similar experiences?
The tolerance on caps can vary a good bit. 20% is not uncommon if you are using certain types.
thanks for making this great video! super helpful!
Glad you found it helpful!
HI There, Very good explanation and testing, thank you.
Is it actually a positive offset frequency?
Hey, just found your Channel and you deserve way more subscribers. Did you check out the Circuit of "Great Scott"? He used just one poti. Would love to see explanation of you about the Circuit! Keep up the good Work!
loved it very much
Jason, can you demonstrate a circuit like this with variable frequency and variable duty cycle in the form of a clock pulse generator (LFO), please? Frequency range from say, 1hz - maybe 50hz?
Thanks for posting. There doesn't seem to be talk of Mark space ratio when it comes tovthe 555. My application required 0.5 on and 4 secs off. I easily got 4 on and 0.5 off so then I used a transistor follower to invert it. I'm going to your circuit .. looks like it's just what I'm looking for.
Thanks for the great video. What if instead of pot divider and two diodes we want to control DC with voltage, let’s say, from feedback?
This is excellent. Now with a variable capacitor you coud also vary frequency then. Though I believe they don't have large ranges. I am thinking this could make for a pulse unit for an older tig welder, splice in between the pedal and welder.
Glad to see you post another video. Your explanations are great.
If you wanted to use a 555 to control the output of a 4017 would it be better to control the duty cycle or the frequency?
I would think that in most applications you would want to control the frequency to get the counter to output the signal you desire.
I would like to build a source ... Buck or Boost converter. From this clip, I understood how to adjust the output voltage.
Question !
Have you made a clip in the past, or can you make one in the future, to show me how I can order a Mosfet IRFZ44 transistor (or other model ...) to withstand a 5 A load?
@skinny R&D, Can we vary the duty cycle by varying the capacitor(s)? Is there any method to do that?
good work. is it possible to adjust frequency and duty with a single ci555? can you help me with the explanation and diagram to do it? Thank you!!
If you made r2 an adjustable resistor as well, would that allow you to then adjust the frequency as well? Seperate from the duty cycle?
Brilliant explanation....one thing I must say, this is not Skinny R&D anymore....
Is it possible to also change the frequency with another potentiometer while keeping the feature of changing the duty cycle as shown in the video?
A good drive signal change for Servo Motors. I will give it a try!
Very Nice video on 555 pwm signal duty cycle control effectively...
let make such a video on convert this pwm signal to sine wave n discuss how to achive in case of sine wave signal..??
great video - I need help with an arduino electronic project - is there a service that can help?
thank you
Wondering if there is a way to replace the potentiometer with solid-state components so the duty cycle can be electronically controlled?
Also in this case you can save one resistor if you use the output pin 3 to control charging and discharging of the capacitor leaving the discharge pin 7 unused.
is there away to do similar thing - keep duty cycle the same while chaging frequency?
Can you trigger this with an external signal? to sync its operation time?
very nice discription with 555 pwm generator...
can u make a detail video on how to convert pwm signal into sine wave signal with tiney 555 chip...?
Wow ! What a fantastic video ! Thank goodness the ‘alerts/notifications are working !
I absolutely love this , detailed and in depth , ....and intense maths ! - ....made that little bit easier !
Bravo and Thank You ! Very educational 🤓🤓🤓🇬🇧🇨🇦🇺🇸🍻🤝👍🏻💪🏻😎
..... Questions I have for you , if you have time to answer them ....
Q 1 : Can a 555 timer chip be used to produce 1Mhz frequency ?
Q 2 : ....if so , in what form , AC / DC / Pulsed etc ?
Q 3 : Can it be used to to produce the output of a transformer ?
..... why ? .... I am trying to find a method , practically any way , to produce a diathermy machine that outputs (of the electrodes ) a 1Mhz frequency , [300 ohms] 75-105 watt power , and possibly ranging from 10 to 55 KV with a 5ma to 60 ma , and I am stumped on how to do this at least semi-professionally .
I have most electrical tools yet I am still a novice at using my Signal Generator and DC supply in these instances .
If you have any answers I would love to hear your input , every bit of info helps ! 👍🏻😀
Thanks for watching! As to your questions:
Q1: It looks like it can if you buy the right type. This one claims it can: www.digikey.com/product-detail/en/texas-instruments/TLC555CP/296-1857-5-ND/277502
Q2: It will be an AC, square wave output.
Q3: I'm not sure this is possible with a 555 timer alone especially with the characteristics you are looking for. Maybe you could use the timer to produce the signal you want and then step that signal up using the right circuitry.
Seems like quite a build. Good luck!
Sir for 32-100V and 0-28A dc dc converter, potentiometer should be increased or we have to change with R1, R2 and C1? please reply me as soon as possible
How can you make the duty cycle controlled by a VOLTAGE--the frequenct can vary a bit???
THANKS MUCH OR THE GREAT VIDEOS!!!
May I suggest a slight variation that uses a single potentiometer and no other resistors: (1) connect a potentiometer center tab to pin 7 of 555. (2) connect one end of the potentiometer (the first end) to pin 8 and then connect pin 7 and pin 6 via a diode forward biased toward pin 6. (3) connect pin 6 to the other end of the potentiometer (the second end) via a diode that is forward biased toward the second end of the potentiometer. This way, the period is constant and given by the potentiometer resistance (end to end resistance that is) but the duty cycle is variable from 0 to 100% within that period by turning the potentiometer knob.
Cool, thanks for the suggestion.
This is so good but can i let it work on 12v or the circuit will burn
what is the value of the diode? can i use in4007?
What I've mostly seen is a circuit that does not use a 555. The 555 uses 2 different resistances, one for charging and 2 for discharging.
The simple circuits I've seen use a comparator or opamp, plus the pot and two diodes. The same resistors are used for both charging and discharging the timing capacitor so the pot does not change the frequency.
Instead of using the 555's pin 7, try using the output of pin 3 to drive the pot and diodes. In other words, see if you can get rid of the discharge resistor. Thanks for the video.
Hello I have a pulse wave coming from photo diode, with T1 = 50-60us, and total time period is approx 20ms. Since this is too short a period (T1) to be detectable I want to increase it to 5ms, keeping the total time period same, how can I achieve that?
Nicely explaination
Thank you.
I think from another post there should be a way to replace the potentiometer with a control board? Motion control or like? How would one go about doing that using the 555 to control mosfets or control interface like an esc without using a manual potentiometer?
Try using something like this: www.sparkfun.com/products/10613
Looks who's back!
You miss this rugged handsomeness.
Just a tip if you use a dual gang 50k linear pot with both centre pins tied to gather and 2 pins from opposite sides one from one gate and one from the other to make a single pot you can adjust the duty cycle with absolutely no frequency change like UL get with a single pot and logarithmic pots
Hi,
Subhranil here,
In your case C1 that you have used was 820 pF, So should it be change for different ICs or I can use 820pF with any 555 IC for controlling the duty cycle.
Waiting for your valuable reply.
Yours faithfully,
Subhranil
Nice one!
Thanks!
Hey,
I need 400Hz 555 PWM output and at 50% duty cycle
can someone help with the calculations
So is this mostly about controlling the rate?
Is it possible to change duty cycle from 0% to 100% automatically, without a potentiometer and same in the opposite way?
Very useful video. I wanted to know what is the value of C2?
100nF, but smaller can also be used. It is not critical to have it specific value.
I'd like to see projects using a 556. Please.
Nice!
Very nice tutorial. Thanks! Still a long way for me to understand how to make an additional brake blinker that lights initially two times e.g 2Hz and repeat after e.g. 3 or 5 seconds . I might do it with two different lights or a single light load. While on motorcycle, I try to get some extra attention without annoying people too much. I plan to leave the main brake light intact. :D
I guess I should cook up something out of this but with transistors maybe.... (possibly smaller form factor than relays)...
I might just try to add two transistors in the output similar to your other video where you controlled additional 555 circuits but I replace those 555's with Light-1 and light-2 ... ruclips.net/video/mBA9uPeEzw4/видео.html ...So using only one 555 with "advanced" duty cycle adjustment in this video and the transistors switching lights on hi and lo signals... First triggering light-1 and then light-2 leaving it on for a long time before the next cycle. It is a bit cheating not turning the light-2 off before next cycle starts but might do it's task ok and might work in other light configurations too with original brake light in equation. We'll see if I ever get it done. :D Now someone say this is 4$ ebay? :D
Very good video !!!!!!! which value of capacitors should I put, if I don't have some 820 pF ?
It all depends on the timing you want.
@@Skinnyrd Thank you very much for your fast response.
I use an Op-Amp to control frequency AND duty cycle independently.
I built this circuit as you designed (I think). Is this circuit suppose to repeat itself. It seems to run once. Is there a way to modify it to flash variably?
Yes, the circuit should repeat itself.
very nice tutorial simple and easy to understand. keep it up so many people will benefit fr u.
i have question how to make an oscillator using crystal with adjuatable frequency just like u did in this video
thanks and GOd bless u always and yr family
Is your question how to change the duty cycle using a crystal oscillator or change the frequency or both?
higher
thanks for yr reply. yes sir thats my question. fr what i observed using crystal is more stable than 555, but dnt know how to put an adjustable one.
People use crystals when they need a solid, stable frequency. If you need to change the frequency coming out of a crystal you can look into using a counter/divider IC to adjust the frequency in discrete quantities.
Skinny R&D Ok thanks hope u will demonstrate someday if u have time. im new to this kind of things actually i only learned fr u how the 555 timer works. yes i want to use the oscillator in a flyback transformer , last time i used 555IC the frequency so erratic kept on changing low n high. i saw fr other video he uses crystal oscillator and demonstrate the diff between 555 IC ang crystal. the crystal does not affect whatever ambient.
but I got the same result with only a potentiometer and one resistor... when I adjust my potentiometer between pin 6 and 7 I can obtain a wide range of duty cycle anyway..
I like your teaching 555 timer thank you . love your tech
Which capacitor is use if we want to filter this output voltage?
What do you want to filter? DC or AC component?
Saved my ass in time!
Great video! One question, can I make 20 sec on time with 555?
Thanks! I'm not sure I understand your question though.
Ok, can I make 555 timer that will give high signal for 20 sec. So when one of 555 pin get high 3 v, to hold load high for 20 sec? Sorry for bad english :)
Yes you can do this. You will probably want to use the 555 timer in monostable mode. Here's a video I made about it: ruclips.net/video/057q6v7uwwU/видео.html
Great, thanks on your help.
Nice!! is there any way that i could control the timer duty cycle using a controller lets say an arduino
@Yazu Razbhandari from my understanding you wouldn’t need a 555 and the uno can control pwm as it is. Unless you’re referring to a motion control output for something like spindle control than that is a good question I’d also like the answer too. There is always a way but is it simplified where it’s worth the effort involved?
I actually figured out how to decrease my cap size to 1000uF, R1 & R2 = 62.8k and a 250k Pot that should give me a 5 minute cycle. Actually, I am mimicking the pot using resistors totaling 250k with 125 on each side of the cap discharge to get a perfect 50/50 split. It seems to work wonderfully, except...I have noticed that the first 1/2 cycle (ON time) is always about 70% longer than expected but then everything falls in to a 50/50 cycle. Anyone know why this is?
Can we achieve zero percent duty cycle in this? How to achive that?
if I put a trimpot in place of R1 will it control the frequency?
All the choses resistors and also the pot(and off course the capacitor) have an effect on the frequency. I made a spreadsheet for this circuit, to determine which kind of resistors or pot and capacitor I need for a specific frequency and the range of duty cycle I want to control. And it works. Thank you very much for all the great info Jason. You are a great help to me.
@@rolandberendonck3900 hello mr roland i am interested in generating a constant frequency of 7.83 hz which is the schumann's frequency can u help me select the values of the resistors and the capacitors and the pots to generate a frequency of 7.83 hz. My email address is minocherdar@gmail.com i would be obliged if u would help me out
I am also curious is a variable resistor at r1 would independently control the frequency.
To which pin do you connect the oscilloscope? Sorry I'm just a beginner
Should be pin 3.
@@Skinnyrd That's what I thought, but it's not giving me a square wave on my oscilloscope. Thank you very much .
What does your output look like?
@@Skinnyrd Just like a straight line with lots of distortion or noise.
Sounds like something wrong with the circuit. Sorry I can't help. Double check all your connections.
Nice video! But can anyone make circuit which has constant duty cycle having varying frequency using 555?
Yes they can. Check out this video around the 13 minute mark. ruclips.net/video/WqGq9Yv1d_U/видео.html
Which diode use in this?
1N4001 General Purpose Diode
@@Skinnyrd Thank you🙌🙌.
You're welcome!
Is that pwm?
Yep. You could use it that way.
where have you been??
In a deep dark hole called class development. I'm done now so I'm hoping to put out some more videos.
Im not even a native english speaker and I full understand it. Thank you