PWM Tutorial in HD

[Ltb0b]

Q.Q ty

[FrozenHaxor2]

Does anyone have an EAGLE PCB Project for this and could share?

[siiimonz]

I actually did like to learn about PWM! :)

[antegas]

As custom you videos are very helpfull. Thanks a lot.

[busybjorn]

Regardless of the duty cycle and though the average voltage will be lower than the input voltage, it still peaks at 12V (or whatever input voltage is used). For a 12V lightbulb this will not pose a problem but what if the device can ONLY run on 5V? The average voltage might be 5V but the 12V peak can be enough to kill the device. I still don't fully understand this part.

[Afrotechmods]

@busybjorn Well if it's a 5V device then the 12V peak would kill it. So don't feed it a 12V PWM wave.

[MrSiruz]

This is an awesome Tut. i have to use the same Technic like you for the motor. One thing is that i have to use a pic : 18f4550 Do you have a tut for that ? Because i'm very new to Pic programming.

[kakshi264]

thank u sir. it was very helpful

[AcousticBruce]

Why not just use a potentiometer to adjust voltage? What is the benefit of making a squarewave and adjusting the PWM?

[SamHarrison93]

Hey Afrotech I've made this circuit with a motor. It's running on an 8.4volt 1.5 amp battery. I can't get the motor to spin at all. Yet without the pwm it works fine. I've used exactly all the same components as you. Also I can't get LED's to work either. Any advice?

Thanks

[bboyzhauchia]

OMG THIS IS MUCH MUCH EASY TO UNDERSTAND :)))))

compare to my lecturer who yelled at us :" GO BACK TO PRIMARY SCHOOL IF U DONT UNDERSTAND WHAT I'M TALKING!!"

:D

[homayoun2012]

Thanks!



[StupidIdiot12345]

Very well made video.

[MrSomeone4321]

PWM is oslo used in D Class Amp ;)

nice tutorial! Tnx!

[diaracing]

I sent this question to your inbox as I dont know in which way you frequently check your followers.

I just need more info in case of using the DAQ usb-6008 via its analog output channel. I mean for controlling the duty cycle where I input the analog output of the DAQ in the schematic you provided and the further modifications if needed for the provided schematic connections ?

Thanks in advance

[Tootcroll1]

@diaracing usb2.0 is only rated up to 500mA I have pushed them to just shy of 750mA what are you trying to run? IF it's just leds follow the wiring he made in the video otherwise you need to use your daq to signal a relay or logic circuit with an oscillator and another power supply. It takes a lot of current when using low voltages such as 5v from usb.

[Aviator14]

Couldn't you just simply use a rheostat to control brightness of lights or control the speed of a motor? Why do you need the PWM circuit?

[MrZeus7]

@Aviator14 I think the advantage of this is that with the rheostat, you're generating heat because the extra voltage goes through a resistor, instead of not being used at all like in the PWM circuit. Someone correct me if I'm wrong :)

[3omary7]

i did it by using 1.5k instead of 1k , but the circuit still working

thanks that was helpful for my project

[wow1022]

don't forget about car amplifier power supplies

[bcsupport]

Can you describe how the frequency of the PWM effects the load and how I should choose what freq I want to use ? or suggest another article ?

[varunchopraapj]

What a great work Dude !!!!

Keep it up LOLzzzz !!

[stupefythyself]

Thank you!!! The difference between using a voltage regulator or potentiometer and a pulse width modulator really cleared a lot of things.

[Mariordz88]

would this work if i use a Tip 120 darrlington transistor??

[AxelTiger]

Fantastic tutorial! very clearly explained, but a few questions; how many led's could you control using this PWM? (Im looking at controlling a large array of leds) Also, could this pwm control a 12v motor without any troubles?

[AxelTiger]

Great tutorial, thanks for posting it!

[dibagio2]

It´s good, but Can you put the circuit diagram or another link to watch it please?

Really thank you. Just I got a trouble With the resistence bulbs, we see an annoying flicker.

[ChicoDaRave]

Hey very nice! It remembers me a bit of Kipkay voice and way to do the videos.

[Nadrealis]

So even though the square wave form is going up to 10 V the circuit only sees 5 V? Am I understanding this right?

[CmdrTobs]

@Nadrealis yes on average, if you want to power a simple device (light) that wants 5V but you have a 10V source switching 10V on and off 50% of the time would likely power it fine. This is better than using resistors to waste 5V from your source as heat. This method becomes unsuitable for complex devices that may blow if they receive 10V for even a split second or complex devices that need a smooth DC voltage (like microchips). In that case your better of using resistors to waste the Voltage.

[osnoflaster]

thanks a lot!!

[frostseer]

Great videos.I learned a lot from them

[KaslarProductions]

can't you just starve the led's for a dimmer? For a demo this was awesome but in practice wouldn't just a pot be a tad bit simpler?

[odessa999]

@KaslarProductions Try dimming Led's with a pot and see what happens :)

[KaslarProductions]

@odessa999 Wired like a voltage divider works just fine.

[odessa999]

@KaslarProductions Maybe good enough for your purposes, but you dont get a such a wide dimming range like as you do with PWM. Also just dropping the voltage the LED will just cut out when it falls below its forward current voltage.

[KaslarProductions]

@odessa999 true enough... for more accuracy I usually throw on an NPN tranny with the pot wiper connected to the base and LED+resistor on the emitter. Collector on +V obviously.

[mashersmasher]

Are there multiple standards for identifying ceramic caps? I have found some that have both numbers and letters.

[tjnlsn255]

Ok cool.... Thanks!

Will do.

[tjnlsn255]

Thank you!

Would a 5v zener diode work? Would I need a current limiting resistor with it if it had say a 1 amp rating?

Regards,

Todd

[Afrotechmods]

@tjnlsn255 Huh? No. Zener diodes are very crappy voltage regulators. Avoid using them when 30 more cents gets you a proper regulator.

[tjnlsn255]

If my 24v dc motor power supply is two 12v batteries in series can I just use power from one of the 12v batteries to run the 555 circuit or should I use the 12v to run an LM317 and then run the circuit from the LM317?

Thank you and great video!

[Afrotechmods]

@tjnlsn255 Both ways will work. But I would use the LM317 method because a stable voltage over time will mean the frequency and duty cycle won't drift as the batteries discharge.

[TheError404]

Great tutorial, wait, did you get that motor from VCR player?

[HHOhybridBuilder]

Can I use a step down transformer 12 volts to 3 volts as replacement for the electric motor? I asked this because I needed a 3 volts power source out of a 12 volt lead acid battery. If so do I still needed the diode for protection? ( Lots of THANKS )

[blacklust007]

@Afrotechmods would you do a simple communication application of PWM? thanks!

[blacklust007]

great video! :) i just have some questions, i have accomplished similar effects for light dimming and motor speed control (in my case i used it as a cpu fan controller) by using lm317 voltage regulator and a potentiometer. so here's the question, what would be the advantage of using PWM over plain voltage regulation using lm317?

[Afrotechmods]

@blacklust007 Excellent question. The LM317 is a linear voltage regulator which is inherently inefficient. It burns up excess voltage as heat to get the output voltage you want. Power loss will be (Vin - Vout) * Iout. PWM is switching between fully off and fully on, so it will be much more efficient and generate less heat.

[blacklust007]

@Afrotechmods Thanks for that well explained answer :) is this the same method used for the PWM fan control system used by current computer motherboards?

[nyehnyi]

@blacklust007 pwm will maintain motor torque even you slow down your motor. you can check my PID project on my channel

[bleachworthy]

haha, sweet! I used to be a big fan of the afrotech site

[nonodalloo]

Great Video , thanks!

I have a question,

I need exactly the same circuit for my project to drive a 12V. DC motor with maximum current 3.5 Amp..is that possible with your circuit?? If not, what are the main elements that I should consider and/or change??..

Thank you :)

[Afrotechmods]

@nonodalloo The main thing that will determine the current limit is the transistor you use. You should try find a low resistance N channel MOSFET, put a heatsink on it, and get a schottky diode rated for 5A to put in antiparallel with the motor.

[nonodalloo]

@Afrotechmods Sounds good...I will try that and let u know...thanks!

[evacio779]

Ok, (it was 1,36 sorry..) 1,36 KHZ.. now how I choose which frequency is better?

[evacio779]

Ok, 1,26 KHZ.. now how I choose which frequency is better?

[averagemale2000]

I like this video, well done and explained.

[theplayboy92]

It just cleared all my woes about the fancy PWM....oh it's easy, so easy. Thank you.

[BIGTROUT01]

I don't know why anyone would dislike this video. lt may either be too basic for them or perhaps completely beyond their comprehension. As for me, I have learned from, and enjoyed watching many of your videos. Thank you very much.

[scrapkilla321]

could someone tell me why you would need to use multiple mosfets and how

[Landotter1]

@scrapkilla321 Depending on the circuit topology (design) you may have multiple FET's. In the case of the single transistor with a 555 timer, if you put output transistors in parallel, they all share the total load equally, in theory, but nothing is perfect. :-) If you have a 5 amp load and you put 5 transistors, each transistor carries 1 amp and the associated heat dissipation with 1 amp. If you just have 1 transistor, that single transistor must bare all of the heat and current.

[Landotter1]

@Landotter1 What you will need to add is a biasing resistor to the drain of each of the FETs or the emitter of the bipolar transistors. This resistor should be roughly .1 - .5 ohm 5 - 10 Watts. Radio Trash used to sell them but I don't know, these days. Any hifi repair shop will stock them too. Any blown up power amp will have them. In the hifi world, they are called "emitter resistors"

[Landotter1]

@Landotter1  I mis-stated the FET lead to put the bias resistor on.... C o r r e c t i o n..... You put the resistor on the S O U R C E lead, N O T drain S O U R C E.... not drain...... Sorry for the mistake!

[scrapkilla321]

@Landotter1 ok thank you i wanted to know cause im going to be building a pwm speed controller for a bike in the near future

[Landotter1]

How about doing a part 2 vid on basics on feedback so when heavy loads are applied, the duty cycle will increase to a set value and change back to low load value and no baby sitting. Think a 556 timer will do that right? I forgot...

[spelunkerd]

Good video, thanks. Sorry for being a little dim. How does a diode in parallel with a motor prevent the motor from overheating?

[Landotter1]

@spelunkerd If you energize a coil like in a motor, what happens is, you establish a magnetic field across it. When the power pulse goes away, the field collapses back across the windings, inducing a voltage back across the coil. Depending the value of that coil, it can be a fairly high voltage. That voltage can destroy your transistor or FET so the diode blocks such voltage and sends it back to the coil to be dissipated instead of across your transistor. This effect is called "back EMF".

[Landotter1]

@spelunkerd Also what the diode does is help eliminate what are called eddy currents. Eddy currents flow any direction within a magnetic medium. These fields will collide with and interupt the fields that the control source feeds into it. At these areas of colision, heat is generated, and sometimes, lots of heat. Designers of motors and transformers design spacific shapes and other things into the magnetic medium, to eliminate eddy currents, thus reducing heat buildup.

[spelunkerd]

@Landotter1 Thanks. 

[hannobisschoff1]

keep up the exlnt vids.thnx

[Ibringthetruth1]

What do the capacitors do? no explanation.

[madamerotten]

@Ibringthetruth1 C1 is alternately charged and discharged by the 555 to establish the oscillatory frequency. This type of circuit is called a "relaxation oscillator." C2 filters a voltage provided by the 555's internal resistor network to eliminate noise. This resistor network establishes the voltage levels at which the first capacitor is charged and discharged.

[Ibringthetruth1]

@madamerotten

Thanks.  excellent reply!

[Ibringthetruth1]

Where do the battery hook up to. Schematic shows couple of 12 volt leads.

[fabmkk]

very good, 100%, thanks!

[enasin21]

thanks for sharing..... now i know.... :)

[16Tstar]

nice

[rodrigoimagens]

Really nice this vídeo!

I was just about to do it when I noticed tha those leds were conected in series.

I would like to make a parallel circuit with 12 leds in 12 volts. Can I use this method to put them working?

Thanks!

[rodrigoimagens]

Really nice this vídeo!

I was just about to do it when I noticed tha those leds were conected in series.

I would like to make a parallel circuit with 12 leds in 12 volts. Can I use this method to put them working?

Thanks!

[haikaz]

Thanks for the video helps alot!

[Veo77]

Superb explanation! I had a hard time what the point of PWM is. Thank you for the great vids... hope to see more.

[sponkii]

Hey, very good explanation and good images..

one can with good benefits replace the NPN Bipolar Transistor that you show on the image with a mosfet..

some of the main benefits are.

Eliminate the input resistor (known as a base resistor on a BJT)

Allowed faster switching speeds.

Lower on resistance

In most cases cheaper

Lower risk of thermal runaway (due to the thermal behaviour of a Mosfet)

Note that it is not possible to have a 0 to 100% duty cycle with only a 555.

[jwhill15]

Could you use or modify this pwm circuit slightly to drive a 24V motor?

[Afrotechmods]

@jwhill15 Sure. Use a separate power supply for the 555, (roughly 10V will do) and then 24V will go on the high side of the motor. Make sure the grounds are all connected.

[sypha0x]

@Afrotechmods So technically, there is no limit to the amount of Voltage & Current one can PWM with the 555 timer IC, as long as your electronic components are electrically capable on the high side of the motor? Then in that case you would switch it "on" & "off" (like your transistor video) or using an IGBT (Insulated-Gate Bipolar Transistors) [Which btw, some can even go as high as a rated current of 1,200A & a maximum voltage of 3,300V] or a relay for heavier loads. :)

[sypha0x]

@sypha0x Also some have very fast switching times about 90ns for the IGBT's now with the current third-generation ones are even better, with speeds rivaling MOSFETs. (I know I sound like a commercial lol)

[WongLiangXing]

thankyou very much!

[clayclay100]

Yes!! Very informative. I will be using a pwm to control the amp's to my peltier cooler. didnt think it could be use for this application, but its seems that its is being used for all kinds of apps. thanks for the vid!

[pablojamaica1234]

Quick, simple and covers all aspects. I truly learned from this video

great upload

[hcastr1]

Excellent Tutorial!

[kingyoShin]

cool!!

The mechanism may be comprehensible :D

[D081]

excellent

[tushargt88]

hey...thanks for the video......very rarely do i find such a well explained video on youtube....cheers!

[noospaseisde]

Thanks mate! :)

[marcuelcajon]

Damn you got some BASS in your voice. Nice vid

[nickcars100]

hi...i have on a question. is this used to create ac current or just to pulse the current....and aslo...explain the wave form exaclty please..because from what i am seeing the current is moving in that wave form or that is just a diffenrt view on the screen ThANKS

[cybhunter007]

@nickcars

PWM is used both in DC and AC circuits. In AC circuits SCR's (silicon controlled rectifiers) are used (no timing circuit required), while DC tend to use timer circuits like the 555.A resistor array and a capacitor are used to control the comparison voltage to allow current to flow

for a 555 timer animation try looking at this link

williamson-labs (dot) com/pu-aa-555-timer_fast.htm

[thejetdrvr]

Great vid! Thanks.

[thewii552]

can you use a lm555 in plase of the ne555

[namzer0]

is this circuit also used in switching power supplies?

I wish to make a capacitor charger using this technique in a switching inverter

[wayne205stevens]

Brill vid! Could I just ask what frequency of the output would be on this please?

I've also seen other circuits like this but with an added LM393 Dual Comparator, could you please tell me why it has this?

Many thanks :)

[Afrotechmods]

Ahh if I remember right I built this PWM circuit to have a frequency of around 1kHz. No idea about the comparator. There's a million different ways to design a circuit in EE.

[ishman1]

Great video fellow VAIO user. Thanks for the tutorial.

[azz1muth]

Hi,

does anyone have any idea how could I control the potentiometer digitally or any other way I could control the voltage on DIS pin of 555? Let's say instead of rotating the potentiometer's shaft, I would somehow control the voltage supplied to 555's DIS pin and that way control a DC motor's speed in my project. Thanks in advance for your suggestions.

[wayne205stevens]

@azz1muth Hi, You could use a digital potentiometer I've seen them before as a simple 8 pin sufface mount then you can use 2 tactile switches for up/down, I was looking for some before to use with a LM317 regulator, I hope this helps, just look online should find them there :)

[Afrotechmods]

Yup. There's also loads of prebuilt motor controller solutions out there. Just search for motor speed controller. Also, check out Robot Marketplace.

[azz1muth]

Nah, I gotta do one myself coz I need to show I know something in electronics :)

[wayne205stevens]

@azz1muth Hi again, You have a look at the 4017 Decade counter, I've used this in quite a few of my projects, Its a fun IC to play with also if your going to use this IC look up Debouncing Circuits Its so your switch input dosnt make the chip turn on/off (hi-lo) very fast as the contacs meet they actually bounce of each other very very fast, the circuit uses a resistor and capacitor in parallel with each other to counteract this... hope this helps :)

[lexichronicle2]

@azz1muth "does anyone have any idea how could I control the potentiometer digitally"

stick a digital potentiometer in place of the mechanical one. a ton of the big semi guys do them. they often sell them for volume controls in digital gear. for example, in the volume circuit of an mp3 player, so you can change the volume by tapping a button rather than turning a dial.

[IngBrando]

Thanks for sharing it with us!

[itzmeydna]

more of these vidoes please!!!

[Afrotechmods]

Working on one right now!

[preludefan]

thankyou for that, im going to use your design to set up a fast idle valve for my honda prelude- it had on originally, but mine is very modded and my aftermarket ecu does not need it to perform its functions, however the air con unit still needs it so i will build this circuit, and fit it to the car, idle the engine and turn the pot till it sits at a stable idle with the ac on!

[piyushpv]

It's awesome. I heard PWM many time but after watching this video I know that fully.

Thanks a lot.

[emiltech2]

wow, thats great! i understand a lot more if your were the instructor of our technical school. thanks Sir!

[djlukicavalheiro]

Really nice you initiative! =) Good Work

[robbmeex]

"I did, Thanks for filming!"

[intheshitter]

Thanks man this saved me from pulling my hair out.

[AttilaSVK]

I wish my teacher would explain me PWM clearly like on this video. For me it wasn't hard to understand, but my classmates didn't get the point, until I explained them. In fact I knew what PWM was before I went to secondary electrotechnical school :-)

[popstarfule]

nice video, thanks for making it :-)

[Flea5000000000]

verry good

[daxweb]

i love your video style!

[pasanlaksiri]

Thanks

[neves321]

Thank you, Afroman! That explains a lot!

Cheers!

[valko007]

this is a very well explained tutorial A+

[steffankaizer]

BEST VID EVER really i think it should be featured just because it is so awesomely professional

[elimenohpee182]

very nice! now you should make a video on how to generate pwm through software :)

[aiklarung]

You can use Audacity I believe, it has a tune generator

[elimenohpee182]

I meant using interrupts mainly for microcontroller applications. Interrupts always confuse me :X

[Alterstateresearcher]

wow, great video, needed to know abit about PWM and this video laid out a great foundation.

[w0083e5c]

very good video !