Choose Your Duty Cycle - 555 Timer PWM - Pulse Width Modulation - Simply Put

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[@bhargavgudapati9838]

This was a very informative video, even after 4 years, thank you so much for making it so easy to understand! Im trying to design a circuit to pwm control a fuel pump based on an analog voltage, and this came in handy.

[@VeryMuchBlessed]

Excellent. I've been looking for a 555 circuit where I could adjust the duty cycle without affecting the frequency. Very good work and explanation. I replaced the 1K resistor with a variable to control the frequency, and I also placed a 100mF capacitor across the Pos and Gnd rails and this really helped to improve the stability of the frequency on the scope. You're a natural instructor. Thanks much.

[@tonybp]

I just wanted to say what a difference your videos make when it comes to enjoying electronics because of your explanations. In other channels it's like they want to complicate things on purpose and that took away (at least for me) the joy of it all. It has been a while since I tinkered in electronics but your videos might change that.

[@simplyput2796]

I think a lot of people just don't realize they're doing it. We all (myself included) tend to project our own knowledge onto others when explaining things, especially if we're having fun and excited and really want to share. I just manage to focus on the "simple" part because of what you say, how frustrating it is for me to try to learn these things from people who make too many assumptions, and it just helps me remember to not get carried away. I'm glad I can bring some of the fun back into the hobby for you.

[@tonybp]

@@simplyput2796 👍👍👍

[@keithking1985]

Wow that was cool. I love this stuff. And I love the 555 because it can teach you so much things. (Well people explaining its workings teach you so many things)👍👍

[@GhostsOfSparta]

This is much cleaner solution than juggling with diodes and potentiometers. Thanks for the video saved me a lot of headache.

[@HerraHazar]

Just found this channel, subscribed.

[@khwezimngoma]

Loved it bro!

[@PunaJussi]

Brilliant!

[@gkdresden]

You can have also linear duty cycle control from almost 0 to almost 100%, with only a single 555 timer and a single capacitor a single potentiometer and 2 diodes. You just have to control the charging and discharging of the capacitor by use of the output pin 3 without using the discharge pin 7 and also without using the control pin 5.

[@Skibidi_Male_X]

Bro I love your videos so don't take this the wrong way, it'd be very helpful for somebody who learns like me to have bigger little things that you stick up on the or colorful things that you stick up, just bigger and more colorful electrical symbols. Thank you

[@Mogwai06]

im just gonna go ahead and admit something that i probably shouldnt... i had to watch this video about eleven times. not because of your easy to comprehend and retain explanations though. youre damn good at this in my opinion and have found myself coming back to your videos anytime they show up in the results im searching for. but no, actually, i had to rewatch this multiple times because i still crack up every time someone says "duty" and its on here a lot. and yes i am way way too old to be so humored at the word "duty," but its something i have never been able to not laugh at my entire life. i fully realize im just a big stupid man-child, at best... ...duty.

[@michaelszczys8316]

Certain people are better at explaining things than others. You are good at explaining this stuff.

[@enriquegonzalez2802]

Respect.

[@gyaviratuz2029]

you have amazing content , you go indepth into electronics , could you do a series where we can do full electronic circuit of a consumer based product , that would be amazing

[@patjosullivan1]

Great explanations, thank you. Working on a lighthouse project and was wondering how to slow the turn/off of the LED to give more of a rotating effect. Using 555, 4017 and S0913s: GutReise 10pcs E10 Screw Flood Led Lamps +10pcs E10 Base,4.5V Cold White Led Bulb Light (4.5V, Cold White)

[@rodriguezfranco3839]

I just did that circuit with the two 555 and a irfz44n fet for a pwm and it works but it is not changing the duty at least not the way I wanted anyways I need to scope it and see the actual wave form , I am gonna use it for a tesla coil interrupter , your video help me a lot

[@ac4nl]

Greetings. Good work on your channel .. Hope it continues to grow.. As far as why the RL resistor on the 555 output.. I am GUESSING the output is a totem-pole circuit providing source and sink capability. Totem-pole outputs normally have around 2.5 - 4 volts high levels. If you need rail-to-rail levels, for interfacing none TTL devices, you can add a RL resistor pull-up, however, this will increase your output impedance. Take a look at TTL Totem pole output stages and see if that helps you. Enjoy A.

[@simplyput2796]

Hey, that's an excellent thought, and reading about TTL totem-pole push-pull outputs, that sounds exactly like what's happening here. I bet you're right.

[@michaelszczys8316]

This looks like it could be what I'm looking for. I need dumb little timer to turn a thing on for about 1 second, then wait about 10 seconds to repeat. Mostly off with little bursts of power every 5 to 10 seconds. Your explanation in this video looks like 555s could do it. Use a long timer to turn on a short one. Then what would really be cool is if I could then run two of them 180 degrees apart from each other. Not sure how that one could work.

[@samuelthabet2114]

Great stuff here! I am a beginner and it's easy to confuse things up. I am now working on a project and I would like your opinion. I am trying to replicate a train with electromagnetic propulsion. Same as the Japanese trains but what I am interested in is the configuration of the electromagnets. Imagine a rectangle with 2 permanent magnets and both of the long sides, then there are electromagnets on the side of the ''road". At this point I need to configure the electromagnets in a way that I can switch their polarity and the period of switching should also change with a potentiometer in order to let the "train" accelerate. Is that possible using a 555 timer or there are better ways that I could use? Thank you.

[@augustolacerda3560]

About the high-pass filter: wouldn't it work with an RL high pass filter? Series resistor with a parallel inductor instead of series cap and parallel resistor?

[@morganchandler5126]

What would be the simplest way to create a pwm signal with a slowly increasing duty cycle ..... Maybe something like a d class amp ......???

[@Ellington_Industrial_Arts]

Love this explanation! But let's say we are modifying someone else's square wave, and we just want the ability to ADD duty cycle? Would you just invert the square wave single into the monostable timer using like a transistor, triggered off the PWM source? I.E. Change the source High duration, into the monostable trigger Low duration. Then the potentiometer would only add to the PWM duty cycle?

[@parapos]

great info as usual ,thank you. one question though , in this video, you are refering to older videos quite a lot, that is actually great, but could you put a link to these videos in the description or something? it is not always easy to find this info , going through a lot of videos when the title is a little different than the topic in question. fwiw, i personal would watch an older video in the middle of the new one, if i needed to. (i actually do, but i can't always find what i need)

[@simplyput2796]

I actually don't know how to do that on KZbin. I'll have to dig into the dashboard thingy and try to figure it out. I could always just put them in the description, I suppose.

[@scottneels2628]

@@simplyput2796 Could you do that please. I do exactly the same thing. Search, find vid, insert old vids to understand prerequisite knowledge, continue...rinse and repeat, with better informed search.

[@abe3775]

I was trying to make something similar, with an analog voltage to control. Vcc to 555 was 3.3 V and my analog voltage min and max were 0-3.3V. But I cant create more than 67% duty. Is it because of the inner 2/3 Vcc control voltage overriding my control input? I am new to this, and I am simulating on Multisim using CMOS 555.

[@Icehso140]

14:41..robot uprising. Yikes !!! It's Space Odyssey 2001...and HAL the computer (Stanley Kubrick and the prediction for the future). Move one letter over int the alphabet for each letter in HAL and you get - H becomes I, A becomes B, and L becomes M...or IBM the evil computer company taking over the world. (At that time) It's gonna happen. I'll discuss it further with my Stepford wife. LOL

[@aboalhassenahmed7270]

I have a weird problem , when i change the duty cycle the whole wave shifting up or down ( the more increasing the duty the more shifting the wave up and vice verca ) How can i solve it please ?

[@ChickenPermissionOG]

Can't you just use two diodes and a pot to control pulse width?

[@totototem1951]

Hi. How can i make a high speed switch to activate a small electromagnet? I'm using a 9v battery as a power source. I tried to use a hall effect sensor and it kinda works but the problem is that the output power out of the sensor is VERY low and it can't power up the electromagnet, so then i did use a transistor activated by the hall effect sensor so that the transistor can deliver a higher voltage from the battery (9v) to the electromagnet but it doesn't work either, it delivers a very low voltage. I also tried to use a laser switch and same thing happens. Then i did use a reel switch and it works but for a very short period of time (one minute or less).What happens with the reel switch is that the on and off is so fast (many times per sec) it creates a spark bridge between the contacts inside the switch and they stick together (on the ON position). the only way i can make the electromagnet work is to make the contact (switch) directly from wire to wire as opposed to using any other type of switch (hall effect sensor, reel switch, etc). I guess that what i'm dealing here is that the switches like the hall effect sensor creates a digital signal, and connecting wire to wire directly is an analog signal, digital vs analog, i don't know... So then I've been trying to build a mechanical switch (contacts made by the wires directly like in the reel switch but with a mechanism to push one contact from the ON position to the OFF position to prevent both contacts to stick together in the ON position and of course adding a diode to prevent the back EMF from the coil to go in one direction. But i haven't succeeded. I'm wondering if i can use a 555 timer (or two of them) to do the switching (on and off) and be able to deliver whatever full voltage the battery has (9v fully charged, or 8v or 7v etc) to the electromagnet. Will this work? if so, how should i connect all the components, and what components should i use?

[@aviandragon1390]

Without knowing anything about your project it's hard to offer great advice, but it sounds like the device you're looking for is an operational amplifier. This will take the small signal from your sensor and turn it into a larger, more useable voltage without loading the signal down. Don't be fooled, however. Op amps usually aren't great at high current output. The output of the op amp could then be used to drive a suitable MOSFET, which should be able to handle the high current draw. If you need to switch your device on and off very quickly (thousands of times per second) because being constantly on will burn it up, then you will probably want to insert a timing circuit such as this in between the amp and FET. You'll need to do some studying to learn how to use op amps effectively. Hope this helps get you on track.

[@digihz_data]

Great stuff. But the point that arduino only output 500 Hz pwm is wrong.

[@XY-vf9mu]

Maybe im a little late but my project is to control different PC Fans independently with Aroduino. Yes there are 3 Pins to get 16 bit Pulses but i want it easy so my ide is tu use an 25khz frequency from a quartz crystal and your timer. Will that work?

[@aviandragon1390]

If you really want easy, just adjust your fans by increasing/decreasing the voltage they are fed. 🤷

[@XY-vf9mu]

i bought the arctic p14 pwm, daysichain. Easy goin xD @@aviandragon1390

[@ironnam8107]

Has anyone used a 555 timer calculator to design a circuit. I've been using 555s to make circuits to control LEDs for a few months now. And the circuit that I end up building is way different then what the calculator said to build. Example if I want a 50% duty cycle the calculator says R1 and R2 will be the same value(makes sense in theory charge and discharge at the same rate). But in practice I have to put a diode in parallel with R2 and R1 ends up being a much larger value then R2 to get any where near 50%. So I'm wondering why my circuits are so much different is this the way it is, cheap 555s or what? I bought a bunch of differnt 555s from ebay and some CMOS 555s for LEDs that run on batteries all of them have been the same.

[@simplyput2796]

I went over this in my astable (square wave generator) 555 video, actually. If any calculator told you that you could get 50% duty cycle with R1 and R2 the same, it was created by a moron, because that ends up being a 67% duty cycle. This method here is the best one for getting an exact (including 50%) duty cycle. The stuff with the diodes is more complex and still is really hard to pin down the duty cycle. This way, you literally can just set it with a trimpot and you're done. Calculators are just a super-rough guideline, and you'll need to tweak the values yourself.

[@ironnam8107]

@@simplyput2796 Thanks for the response I'm just teaching myself this stuff, and thought I might have been missing something. I got my first CMOS 555 about a week ago, and noticed the same thing. I knew a CMOS could not be out of spec as a cheap janky NE555. I was glad when you came out with your 555 videos to help clear somethings up

[@ironnam8107]

and I was getting the feeling that the calculators where made by someone that just learned the theory but had no real experience

[@Haamedtm]

what's the maximum frequency we can get out of 555? and what's the PWM resolution?

[@simplyput2796]

That's going to depend on the specific chip and how it's built. According to the datasheet for the TI NE555P which is close to what I use, the output-pulse rise and fall times are on the order of 100-300 ns, so in principle you could operate that chip at around 1.6 MHz, but pushing it that hard would not give you any sort of "clean" square wave, and if you're chaining two together for PWM then you'll be limited even further, so honestly I wouldn't try to get more than a hundred KHz or so out of it. As to the PWM resolution, that can be as precise as your variable-voltage source (either from a potentiometer or a DAC), and the rise/fall time tells you how close you could get to "true 0%" and "true 100%". You'd really want to just get the chip and test for a real answer, but my "rule of thumb" would be to take the worst-case rise and fall time from the datasheet and add them together, take the reciprocal to get frequency, and divide the result by 10 for a ballpark figure.

[@Haamedtm]

@@simplyput2796 Thank you, subscribed! btw; is there any way to control the 555 pwm with arduino?

[@simplyput2796]

The analogWrite command on an Arduino already is PWM, but the PWM frequency is fixed and depends on which Arduino you have. If you want to use the dual-555 setup to get whatever frequency you need and just use the Arduino as a variable-voltage source to set the duty cycle, you could try using analogWrite with some smoothing capacitors to get a mostly-stable DC signal, but I would actually recommend something more like a DAC chip combined with a serial-in-parallel-out register, so you can use just a couple of Arduino pins to set the value of the DAC feeding the control pin of the second timer.

[@Haamedtm]

@@simplyput2796 Thanks.

[@dalenassar9152]

Could you use a 556?

[@simplyput2796]

Absolutely. Any time you find a chip that's sort of a "combo" of more than one chip, they'll share power rails but the rest of it will be separate, so you can use them however you'd like. Saves on board space and bypass capacitors that way.

[@sasisekharmg7823]

Great Scott has a video where he pulled this off with just one 555 timer! (so sorry I keep referencing other youtube channels) kzbin.info/www/bejne/nH3ElquuYrOAoJo at around 5:40 (timestamp), he just glossed over it so I've to watch it a few times, but, I'm pretty sure you'll get it in one go!

[@simplyput2796]

Oh that's neat. I'll look into doing that.

[@snipersquad100]

why not use a 556 or maybe 3 555's

[@simplyput2796]

A 556 is just two 555s in one chip, so sure, feel free. Why would you need three though?

[@Sarahbuildsstepsequencers]

Am I the only one who always uses CMOS?

[@leblancexplores]

I'm trying to control a 60W fan with an ESP32/Arduino. Until watching this I would have bought a PWM (555 timer, rc circuit, and fet) board and X9C104 (digital resistor). It seems with this circuit I could just control the duty cycle with voltage which seems like it'd remove the need for the X9C. Would this be a better circuit? I would think this would also allow ability to get 0% duty cycle (off) or would I still need an additional part of the circuit to accomplish the off state?

[@leblancexplores]

I'm also realizing this whole fan controller circuit might be unnecessary as with the ESP32 there's already PWM pins. Fan controller would work but would the frequency that the ESP32 operates at be suitable for dimming LEDs?

[@evilcoot]

Sounds like u use a compressor on your voice... i would turn down the release ...

[@crohkorthreetoes3821]

I don't remember what your credentials are, but I have to tell you. As far as thoroughness and understandability and utility of what you are teaching you are on par with "CIA-Spy Guy". And as far as I am concerned so long as you do not attack Nikola Tesla or Prof. Walther Lewin you are just a little bit better in my book. Seriously, thanks for all the information. I truly appreciate it.

[@shitheadjohnson2797]

simply put rules