New simplest PWM generator WITHOUT 555 timer IC (improved version using ONLY transistors!!)

Подписаться 11 тыс.

Просмотров 23 тыс.

50% 1

Ever since I made a video about my transistor based PWM circuit that doesn't need a microcontroller nine months ago, it bugged me that the circuit only worked with a MOSFET to switch the load, not just another simple transistor. After all the idea behind the whole thing was to avoid any fancy extra components like the 555 timer in favor of parts that can easily be salvaged from e-waste, so being quite a bit rarer than transistors, MOSFETs would definitely better be optional not obligatory.
Luckily while designing the circuit for my DIY soldering station I figured out a way to make it work with transistors only - But alas! Another much newer channel beat me to it, and to my dismay his solution was even better than mine!
So in this video we analyze both versions of the circuit and take the best of each to create one hopefully perfect PWM generator!
Here are all the links:
The video on my second channel where I calculate all the component vaues:
• Designing a PWM motor ...
And here the schematics: it's worth noting that I did a couple errors calculating the resistors originally, so all the versions you can download below are recalculated and revised, thats why there is now only one value per component. You still have some leeway, but if you want to use other transistors than direct equivalents you'll need to change some resistor values to accommodate the current gain of those specific transistors.
Steve's Chronic PWM version 12V 1A :
drive.google.com/file/d/1g-D0...
Steve's Chronic PWM version 5V 1A :
drive.google.com/file/d/1BKMV...
Steve's Chronic PWM MOSFET version 12V 30A :
drive.google.com/file/d/1O8kK...
Also check out Steve's channel and subscribe if you enjoy:
/ @bbcircuitsbystevemorr...
Code for the arduino oscilloscope I used:
create.arduino.cc/projecthub/...
-------------------------------------------------------------------------------------------------------
Support this channel on Patreon: www.patreon.com/user?u=81848920
Follow me on Twitter for random updates and personal opinions on different topics: @chronic_atronic
Join r/chronicmechatronic for occational peeks behind the scenes, or general project discussion!
Get my best photographic works on Shutterstock:
www.shutterstock.com/g/Floraf
Or download free stock photos from my profiles on Unsplash:
unsplash.com/@floraf
unsplash.com/@clicabout
-------------------------------------------------------------------------------------------------------
Additional sound effects from www.zapsplat.com
Additional graphics from: www.cleanpng.com/

Наука

Опубликовано:

30 июн 2024

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 105

@BBCircuitsbySteveMorrison 2 года назад

Awesome video. Thanks for the mention. The improvements and final circuit look great!

@ChronicMechatronic 2 года назад

Thanks! I made a couple of mistakes calculating the resistors in the video, but for the download versions I redid everything, haha

@geoffreygriffiths1487 8 месяцев назад

Thank you so much for this. Your title should be "DIY PWM without a micro controller". I have been looking for this information for over a year, and now RU-vids algorithm decides to serve this up. I was ready to give into the micro controller.

@ChronicMechatronic 8 месяцев назад

Thanks for the suggestion! I'll include it in the the description that way it should pop up on search engines for those searches too!

@ChronicMechatronic 8 месяцев назад

Your comment actually did the trick in Google search! (but I added it anyway)

@ChronicMechatronic 2 года назад

I'm so glad this mystery is now solved!! Big thanks to @BBCircuits by Steve Morrison for letting me use parts of his video in my video as well as butcher his circuit!

@SirDzair Год назад

I love your energy man, lol (and your extremely clean explanations that I could hear all day!) (also I appreciate a lot your credit to steve, imagine how much better the world would be if everyone does what you did right there !)

@ChronicMechatronic Год назад

Glad to hear you like it! (recently somebody told me not to talk as much and to shout less, lol) Yeah, I hate when people steal other's original ideas - I think some life hack channels did that with one of my early videos, amassing four times the views... So I hope the shout-out to Steve was enough to make up for the fact that I had a better starting position in the algorithm, as well as set the records straight that it wasn't, in fact, me, who came up with the idea in the first place... Appreciation for a new invention should always go to the person who came up with it first!

@user-mg3qq4ie4p 9 месяцев назад

19:10 19:10 19:59

@MadZax33 2 месяца назад

Hey Chronic, just want to say thanks! I've been trying to make a simple PWM circuit than can be both, adjustable frequency, and duty cycle. With a couple simple mods, I made one that works with this design!! Could not even do this with a 555, so this is better than an actual IC!

@ChronicMechatronic 2 месяца назад

Great to hear!

@keithking1985 4 месяца назад

Just came here from the channel you mentioned.. great circuit 👍🇮🇪

@bjj6708 8 месяцев назад

Your doing a great job, mate, I am 3 × your age, yet still love your concepts I used at your age, and fiddling and experimenting is what it,s all about, having fun and loving it :-)

@fober3317 4 месяца назад

Didnt need a motor controller but it also works perfectly as an pulse generator. Thanks for the great explanation

@Noconstitutionfordemocrats1 9 месяцев назад

It's too bad there's not much interest, because this was exactly what I was looking for.

@klausbrinck2137 Год назад

I know little about electronics, but you explained everything so good, that I had the feeling, I know such stuff since ages, congrats. Sometimes simply wanting to transmit knowledge, lets one do such dedicated work, that it simply works, even with absolute laymen like me !!! I have a proposal: How about designing a PWM generator, that´s gonna switch the gate of an IGBT? With a resistor and a capacitor in the IGBT´s circuit, you can perform electro-discharge-machining. Primitive diy EDM-circuits, use an RC-oscilator, and have no control over the duty cycle/Hz (controlling the duty cycle and requency can be crucial, cause small workpiece-material-deviations seem to work much better with different duty-cycle and frequency combinations, and constantly changing the main R or C of the RC-oscilator isn´t really a good option). With the igbt in such a circuitry, one can contol much more the event, but one would then also need a pwm-generator for this igbt. Here, at 8:10 u can see what I mean ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-AQCpueMkZ6o.html He explains in the comments:"I'm using a micro-controller running at 5v to generate the pulses, this is fed through 3 transistors using a separate 15v supply to drive the gate of the IGBT, I'm using a pair of transistors to pull the gate high and low as quickly as possible to discharge the gate capacitance, through a small resistor to avoid ringing.I'm using a 'totem-pole' transistor circuit to drive the IGBT and rapidly charge/discharge it's gate capacitance, it needs to switch between on and off as fast as possible or it could overheat if it spends too much time partially conducting." Is this video of yours ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-oTV2OqD29w8.html (PWM for HEAVY LOADS!!! Simple Circuits.) maybe the answer? I sadly cannot judge it. In this video, the motor´s voltage and current-draw are double that of what needed for EDM.

@ChronicMechatronic Год назад

I appreciate the comment, but currently don't have the time to look into your suggestion to come up with a decent answer. I'll do when I get around to it :)

@gkdresden 5 месяцев назад

The transistor PWM generator has another disadvantage if you operate it with operating voltages of more than 5 V. During the discharge of the timing capacitors the base voltage at the transistors goes down to - 5 V or even less if operated with higher operating voltages. In the voltage range between -5 to -12 V you will operate the base-emitter diode in avalanche break down mode. It means the charging time is shorter than expected, because a part of the charge of the capacitor vanishes through the base-emitter diode. It is generally not a good idea to operate BJTs with too much negative voltage at their bases. If you have a relatively large capacitor (1000 µF or more) you can destroy the base-emitter diode due to higher currents (the only limitation is the ESR of the capacitor, which can be considerably lower than 1 Ohm for low ESR types). But in principle you can make the astable multivibrator also of NMOS transistors, which can typically resist voltages of +/- 20 V at their gates. You can use 2N7000 for this purpose. And you can also use lower power NMOS transistors for the output stage if you only want to drive a single LED or a few of LEDs in series or parallel. The 2N7000 can drive 200 mA, the BS170 500 mA and the IRFD110 1 A. And they are still relatively cheap.

@Bianchi77 Год назад

Nice video ,thanks :)

@kennmossman8701 7 месяцев назад

Brilliant!!! Elegant and concis

@johanntiu4162 7 месяцев назад

I also experienced the same problem, so I my design used an optocoupler and a string of diodes on one side, and an LED on the other to get a good pwm signal.

@kamleshchavan7451 Год назад

Awesome video full of knowledge , sir can you please make video explaining the working of the transmitter and receiver module circuit , used in RC toy cars etc , how the data transmission takes place in controlling the DC motor used in the toy car

@dougzimmerman3858 6 месяцев назад

As a suggestion on future videos to support closed loop control, consider a voltage controlled PWM circuit.

@dougzimmerman3858 6 месяцев назад

Fun to watch you learn electronics. One minor error, the ‘arrow’ in the transistor symbol is missing. I did like the extra resistor and diode to balance the loading on the multivibrator. A diode-connected transistor could also be used for more precise matching. Have fun.

@ChronicMechatronic 6 месяцев назад

Yeah you're right, I'm usually too lazy to fully draw the symbols when I'm doing it by hand 🤭

@Enigma758 11 месяцев назад

Sorry, one more question.. In Steve's design, I believe the second output transistor (rightmost) IS the driver transistor. Why did you add a 3rd transistor for your driver transistor? I think it could be eliminated. In other words, just use Steve's design for the output stage, but substitute a different "driver" transistor. Thanks.

@ChronicMechatronic 11 месяцев назад

Because I wanted a relatively high output current. One transistor can only have so much current gain, and high power transistors usually only have an amplification of around 40. Steve's design only has to drive an LED at like 10mA, but the base current needed for the power transistor is around 125mA, so I need to cascade multiple transistors in order to reach that. Theoretically you could substitute the power transistor and the one behind it with a power darlington, but at that point you might as well use the MOSFET version. I hope that clarifies things.

@shareyourchristmas 8 месяцев назад

Thank you for the post, Just out curiosity, what kind of current can the final design draw out of a simple AA battery? I was looking for a way to make to PWM that only draws milli or micro amps. Why, I just wanted to see if it is possible to pulse a coil for a very long time using a simple battery for a very long time

@ChronicMechatronic 8 месяцев назад

The circuit on its own (excluding the load) draws about ~12mA at 12 V, or I guess ~5mA for the 5V version. It'll drain an AA battery within weeks plus I don't think it could be made to work on 1.5V... What exactly are you trying to do? There's some ingenious simple clock pendulum circuits out there that pulse a coil for ages and even react to the magnet passing the coil as feedback, maybe something like that could be adapted?

@shareyourchristmas 8 месяцев назад

@@ChronicMechatronic Thanks for the reply. I am trying to do two things: 1. Make a PWM connected to one or pack of a few AA batteries, pulse a coil, add a cap dump to collect the back EMF to charge another battery or supercapacitor pack This can usually be done in a variety of ways, including using PWM square wave generator module, an arduino nano, pic controller etc.. I am assuming, that a PWM generator with a fewer components could result in less current drawn from the battery. 2. Make a wireless power transfer experiment like this one ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-_TLPJugLUeI.htmlsi=pE8Zss_cCUwUzbWd

@shareyourchristmas 8 месяцев назад

@@ChronicMechatronic For both projects, I would like to experiment and find a way, if possible, of making the small battery pack last for as long as possible. There is another project I saw which involved a small pulse motor, but want to do wireless power transfer using the same principles ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-VuEU1x-tXfk.htmlsi=LuyEtOlYYfA7zL7m If you know of a good clock circuit like the one you mentioned, could please point me to the link Thanks

@ChronicMechatronic 8 месяцев назад

@@shareyourchristmas I dunno, 55yrs is definitely a stretch, sounds like those free energy quacks, no battery lasts that long. Electromagnets use a lot of current by design. However I found something similar that might actually work on Hackaday, and it comes with schematic: hackaday.io/project/171859-microwatt-pulse-motor I think it's based on a simple LED flasher circuit. Using one or several coils from a clock movement might extend runtime since they're very efficient. otherwise here's the smart pendulum circuits: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-psHVTiIoAWA.html Hope that helps :)

@ChronicMechatronic 8 месяцев назад

@@shareyourchristmas The problem with wireless power transfer is, it's very inefficient - so if you're sending microamps through your transmitter coil not only will the range be extremely short, but of those microamps you'll only be able to harvest a few nanoamps at best on the receiver level

@oliveraron7642 Год назад

I was wondering if transistors 4 and 5 make a Darlington pair in the Steve´s Chronic 12 V version? Or do the collectors need to be directly connected?

@ChronicMechatronic Год назад

Yes, Q4 and Q5 could easily be replaced by a sufficiently powerful darlington transistor if that's what you mean :)

@weapea Год назад

🤔 well thats why i heard tiny wobbling in the sound at the previous video.. specially at low rpm. And what i need is stable steady powerflow to my motor, cause The motor drives plates that are doing comping (rhythm) for music....

@ChronicMechatronic Год назад

Yeah PWM is inherently noisy, you would need some kind of linear regulator to circumvent the high pitched whining at low RPM. Or try a huge capacitor in parallel with the motor, I think I saw something similar on a treadmill controller

@docmaker-italy Год назад

Hi, thanks for the effort, good job. In the +5v schematic you wrote +12v input, is it a typo?

@ChronicMechatronic Год назад

OMG yes! Thank you so much for pointing out, I'll change that straight away!

@docmaker-italy Год назад

@@ChronicMechatronic no prob, you're welcome. Why don't you give a watch to my last video, so you know what i'm trying to do with your schematics.... Replace the 555 and being more, much more primitive, i love making things simple to the root ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-3_fGys4H3Mk.html

@ChronicMechatronic Год назад

@@docmaker-italy very interesting indeed, why don't you just add the stepper control to the arduino code? Possibly you could also replace the arduino with a cheaper atmega 128 provided the code doesn't use too much storage? And the stepper motor could be replaced by one of the lower precision unipolar ones from old printers, or even a brushed DC motor altogether (which I assume is what you're looking into?) So many ways of shaving off unneeded complexity haha!

@docmaker-italy Год назад

@@ChronicMechatronic i did so at the beginning, then i separated the two circuits in the event i could simplify them, i'll keep working on it

@docmaker-italy Год назад

@@ChronicMechatronic just forgot to say, in my case you think i need a bd139 or a ragular 3904 will do? Consider i have no current draw, i just need the pwm to feed the a4988

@Enigma758 11 месяцев назад

Why not use a single transistor buffer as a previous stage to the driving transistor? The buffer should have high impedance and not affect the multivibrator.

@ChronicMechatronic 11 месяцев назад

Not exactly sure what you mean, but I put in that many transistors to get enough current gain in order to saturate the base of the power transistor

@Enigma758 11 месяцев назад

@@ChronicMechatronic Google "Transistor Buffer" or "Common Collector" or "Emitter Follower) (all the same thing). A transistor in this configuration offers high impedance, so it doesn't affect the circuit, and outputs the input voltage on it's emitter (minus a diode drop). It's often used to isolate one part of a circuit from another. Think of it as a "poor man's op amp unity gain buffer" as it has high input impedance and low output impedance so it doesn't affect previous stage, and can drive the following stage. If you're not familiar with the common collector configuration, I highly recommend learning about it. (maybe I just gave you an idea for another video 😄)

@stevem1097 2 года назад

Mmmmmmm...got to try it.

@DaVeHiLl200 25 дней назад

Hahaha "f**k it" 🤣🤣🤣🤝

@oliveraron7642 Год назад

Hello, where do you put the probe to get the pwm signal on a oscilloscope?

@ChronicMechatronic Год назад

Base of the power transistor for a non-inverted one, and collector of said transistor to get the actual waveform going through the load (it'll be inverted on the scope)

@oliveraron7642 Год назад

@@ChronicMechatronic thanks 🙌

@EngineerManny 10 месяцев назад

I want to program an Arduino to control an L298 H Bridge to control a DC Motor using PWM. Would I be able to use an H bridge made of transistors and then this approach to introduce PWM to my project, then programming an Arduino to use this PWM (transistor circuit) and H Bridge (transistor circuit) in place of a L298 H Bridge?

@ChronicMechatronic 10 месяцев назад

If you want to make a transistor H-bridge and use this circuit to generate PWM, why would you use an Arduino at all? The only way to control this circuit with an Arduino would be via 2 PWM pins at which point the circuit would be useless... If the arduino is needed to control other things too, you can just feed the Arduino PWM into your H-bridge (discrete transistors or otherwise) and skip this circuit altogether. If you just want to control a DC motor bidirectionally via a potentiometer the easiest is to use this circuit and add a toggle switch to either switch direction directly or feed the PWM signal into the right side of the H-bridge.

@EngineerManny 10 месяцев назад

@@ChronicMechatronic So that definitely makes sense. I want to use this circuit to generate PWM inside of my H bridge circuit to understand how they work on a simpler level. Then that will give me an understanding of what the more complex L298 Driver is and how it works, as well as how PWM works on the Arduino was I program it. I am fairly new to this and have a question, how would I add this circuit to my H Bridge circuit to generate controllable PWM via a potentiometer for speed and a switch for direction?

@ChronicMechatronic 10 месяцев назад

@EngineerManny driving an H-bridge with this is relatively straight forward. You just need an H-bridge circuit with two of the transistors inverted like this one: www.talkingelectronics.com/projects/H-Bridge/images/H-Bridge-1A.gif And add a single pole double through slide switch. Feed the PWM signal (remove power transistor and treat what was connected to its base as output) to the middle "com" pin of the switch and connect each of the outer pins to one of the H-bridge's "A" ans "B" inputs. That's it. The PWM coming out of it may be inverted, in that case just swap the outer two potentiometer pins in the PWM circuit and it'll be fixed. The L298 is basically just two H-bridges along with some inverting logic in one component, pulling one input high or low controls the direction of your motor, the other one is to feed in the PWM

@jameswilliam6900 5 месяцев назад

How much frequency generate with this circuit ?

@ChronicMechatronic 2 года назад

@HerrAlien your comment got in the video!

@karthi6548 8 месяцев назад

Hey , I'm a fellow ECE student, who loves doing such builts, i tried this today with bc105B i believe and a 2n2222a, apparently it didn't work, is there a way possible to make it work in such cases, i have the project submission on upcoming monday

@ChronicMechatronic 8 месяцев назад

Hmm, theoretically it should work with pretty much any small signal transistor, and it's not a finicky circuit to get working... Only thing I can think of would be bad connections on the bread board / incorrect wiring. Maybe try to reassemble it on a less worn section of the board? Crappy bread boards are notorious for making bad connection with components

@karthi6548 8 месяцев назад

@@ChronicMechatronic i supplied it on a CRO workbench with 4 , around 4 V it starts my dc motor , but I can't go past 7-8 because the motor will burn.. and i couldn't control the motor using the 47k pot in this 4V configuration, should i try with 12 V input , i also found that the mosfet was heating on 4V , doesn't raising the temp to 12V burn the mosfet.. oh btw i used the chronic pwm 12V 30 amp circuit

@ChronicMechatronic 8 месяцев назад

@karthi6548 definitely sounds like you got something wired up incorrectly. Did you use the same type of transistor in the AMV? It might not start to oscillate with transistors that are too different. Also, replace the motor with an LED and resistor for testing and crank up the voltage to 12V. The 12V circuit doesn't start oscillating under ~8V. And depending in the MOSFET you used it's gate threshold voltage might be at least 4V. If that still doesn't work, a mistake I commonly used to make back in the day was installing the transistors the wrong way round following the orientation of the symbol on the schematic, instead of matching CBE pinout. This is hard to diagnose because some circuits kinda work regardless and others don't.

@karthi6548 8 месяцев назад

@@ChronicMechatronic hey thanks , i checked Everything, can i connect with you somewhere like insta.. I'm seriously im more of a state like trauma haha.. I've been working on this since 7 days

@TahirkhanUnited Месяц назад

How to create pwm 40n 60 ibgt pls help me which ic i use

@kyme32 2 месяца назад

why not replace the leds with optocuplers and use the photo transistor as pwn driver?

@ChronicMechatronic 2 месяца назад

THAT is a good point - never thought of it! It certainly wouldn't influence the frequency of the AMV as long as you used identical optocouplers, though ultimately it wouldn't simplify the circuit as you still need at least one other transistor for amplification to drive the power transistor.

@ranjeetchaudhary3423 Год назад

I want to generate PWM volt step by step without using microcontroller pls suggest

@ChronicMechatronic Год назад

What exactly do you mean, different distinct "steps" of PWM percentage, or DC/DC conversion to different preset voltage levels?

@laszlobenyei483 2 месяца назад

👍

@abdelkaderfaye3237 Год назад

thank you for the video on the other hand can you help me to make a pulse generator on psim with an adjustable and a fixed part

@sargismartirosyan9946 Год назад

Pls reply me !!! Can you make in your new video pls 1.5v to arcs Input 1.5v to powerful joule thief circuit Then put the output to zvs driver or via astable multivibrator or bistable to HV transformer to make arcs good idea ?! :) Pls reply me 😭 I like your work and I'm a fan of your work pls say is it ethical, efficient work ?! Pls 🙏

@ChronicMechatronic Год назад

I'm sorry I don't even understand what you want? Sure it's possible to make a high voltage boost circuit to run on 1.5V... Also I don't take suggestions for video ideas because I myself don't even get to decide what my videos are about

@sargismartirosyan9946 Год назад

@@ChronicMechatronic umm it's this To power idk like Tesla coil from 1.5v battery But extremely powerful Tesla coil

@ChronicMechatronic Год назад

Depends on your definition of extremely powerful I guess... I have no experience with high voltage stuff, but I'm pretty sure you won't get more than a few millimeters of sparks out of step up converter powered by a single AA cell

@emonsahariar9292 Год назад

12:56 bro why don't you choose a black background to show us your oscilloscope output a little more visible?

@ChronicMechatronic Год назад

No offense - but dude, get your expectations straight. This is educational content your watching for totally free. I already spend more time ensuring high production value than many 1M+ sub channels do, even though I get paid several orders of magnitude less per video than those guys. Would be nice if you could appreciate that, and condone petty shortcomings like those lines not being visible enough. Especially since this is literally only a problem when watching the video at low resolutions...

@urnoob5528 7 месяцев назад

Mosfet is a freakin transistor Omg someone didnt go to class It s literally in the name

@ChronicMechatronic 7 месяцев назад

Thx Mr smartypants. I knew that. For anyone not looking for something to nitpick the simple animations might've made it obvious that with the generic term "transistor" I was in fact referring to BJTs. I agree it's an ironic oversight on my part and I could've expressed myself more clearly, but constructive criticism goes a long way, too.

@markskreen3344 2 года назад

0: 59 it also happens))))

@ChronicMechatronic 2 года назад

Yeah 😂

@markskreen3344 2 года назад

I thought that only I have so)) @@ChronicMechatronic

@little2wang665 Год назад

Yout looks like Peter Parker's friend.

@electrovoltmce 4 месяца назад

TL494CN and ICL8038CCPD

@hawkhawk384 10 месяцев назад

Hi .. my man ..can you help me with a 3 volt similar circuit up to 1.2 amps ❤❤❤🎉

@ChronicMechatronic 10 месяцев назад

Try if the 5 volt version works on 3 volts - if it doesn't, reduce all resistor values by about 2/5. And replace the power transistor with one that can deal with a higher collector current.

@hawkhawk384 10 месяцев назад

@@ChronicMechatronic oh man that's relieving ... thanks ❤❤❤🙏👍🎉

@kennmossman8701 7 месяцев назад

@@ChronicMechatronic also as well as low as Vce sat as possible

@4oo4e Месяц назад

man you like jordi

@Xtn1Insecticide 11 месяцев назад

What happens to the second one if you run two pwms in series?

@ChronicMechatronic 11 месяцев назад

It won't be able to oscillate and the output will be a mess

@Xtn1Insecticide 11 месяцев назад

@@ChronicMechatronic what kinda mess, sorry I mean is there a way to make it work I wonder, for sound purposes

@ChronicMechatronic 11 месяцев назад

@@Xtn1Insecticide ooh I see! Unfortunately I have no idea, I suspect the second one will be cut off before it's able to start up, so depending on which of the transistors usually switches first the overall output might just be the PWM from the first circuit or zero. But that's just my theory, the only way to know for sure is to try it out :)

@gkdresden Год назад

Ok, and where can I feed the control voltage to modulate the PWM?

@ChronicMechatronic Год назад

The potentiometer generates the control voltage

@gkdresden 11 месяцев назад

@@ChronicMechatronic this is not true. The potentiometer is part of the circuit controls the currents for the charging and discharging procedures. It is not a voltage divider to provide a control voltage to the circuit. You can't take it out of the circuit and provide a control voltage at the wiper connecting point to control the pwm. You can make a voltage controlled PWM converter by use of 2 555 timers. The first one is a self controlled monostable multivibrator th generate the starting pulses for the second one monostable multivibrator which is controlled by a voltage between 0 and 2/3 Vcc at pin 5. Both timer IC's pin 2 and 6 are connected and have a timing capacitor against ground and a constant current source against Vcc. The discharge pin 7 of the first timer IC is also connected to this timing network to provide the auto-dicharge of the first monostable multivibrator. You see, it is possible to build up a voltage controlled PWM generator but it is not so simple to work with just 1 555 timer IC. You need 2 of them or a 556 timer IC. In this way I made the PWM generator for my class D audio amplifier. In this case you need only 3 555 timer ICs for a stereo amplifier, because you can use the auto-resetting monostable multivibrator for both channels. You also need only one timing capacitor and one constant current source (I used the CR056 constant current diode).

@ChronicMechatronic 11 месяцев назад

I know, after all I designed the circuit, no need to teach me - in which case, why'd you ask this question anyway? I only gave a curt answer to a question that seemed pointless at best.

@HerrAlien 2 года назад

Actually, the practical reason why you want the transitions as fast as possible is to avoid heat dissipating on the transistors that control the load (motor in your case). As for PWM controlling a motor not being interesting - well, I am looking into handling a rebel video card fan, that seems to ignore the PWM signals given by the card itself. So, just saying, PWM and not interesting ...

@ChronicMechatronic 2 года назад

Yeah, well, I said there isn't much interest in PWM control, because overall compared to hot topics like 3D printing & pen plotter there really isn't. And sadly we all need to follow the algorithm... But I found it very interesting, and since I started it last year I had to give you guys the heads up :) As for the graphics card fan, do you want to pwm the entire fan or just replace the signal of the card?

@HerrAlien 2 года назад

@@ChronicMechatronic The fan behaved very weird. Despite the multimeter showing a 25 kHz signal with a 30% duty cycle at the fan connector, the fan would not budge. Only when the duty cycle reached 80%, it would suddenly start, at 80% of max RPM. Anyway, I fixed that with a 3 transistor circuit, that would take the PWM as input, and be able to drive the fan's 12V power line to PWM, and that worked. Basically, treat the 4-pin PWM fan as a 3 pin fan (GND, 12V, tachometer) and apply the PWM on the 12V power supply of the fan.

@ChronicMechatronic 2 года назад

@@HerrAlien Oh okay that's smart 👌 So the third, yellow wire on 3 pin fans is actually a tachometer? 😮 I always assumed it was the speed control line 😂😂

@HerrAlien 2 года назад

@@ChronicMechatronic The colors used (typically) are yellow for 12V, black for GND, green for the tachometer signal and blue for PWM control. I left the green wire and GND wire alone, but used the blue wire from the fan connector as input to the 3 transistor circuit. The 12V wire from the fan connector is powering the circuit, and the amplified PWM signal is then fed into the yellow (12V) wire of the motor. Anyway, a diagram speaks more than 100 words - drive.google.com/file/d/1__-Slovwc48EcyOC4xImLNCIzfuIe6B2/view?usp=sharing

@ChronicMechatronic 2 года назад

@@HerrAlien Yeah, I get how you connected it, I was just surprised by the fact that the third wire on 3 pin fans should be tachometer rather than speed control. Because all 3 pin fans I own have red & black for positive & negative, with a third yellow one I formerly assumed to be speed control. The one 4 pin fan I have is black, blue, red, yellow. BTW the link just pulls up a picture of something in pliers being lasered :)

@MechanicForGMCCars 8 месяцев назад

can some one help my please Im anoyed simplified I need an device that can phase shift an 4pin GM ignition module who uses the mc 3334 ic chip diagram on google its easely found only difference in my module is that the zener diode is missing from the mc 3334 circuet diagram it uses an inductive pick up coil and an e core type ignition coil. Now I need desperatli to try out some how to phase shift my ignition timing I did found some cdi variabel ignition box useing ne 555 timer and an xor gate ic chip some resistors randomli placed so Im not shure wuld that circuet work on my 4 pin hei ignition module . Im so anoyed and confused honestli some peopel say use ic chip ,some transistors,some say use rc box I dono who to belive honestli. The simpel goal is to retard ignition timing so I dont freaze my ass fummeling the destributor in cold weather the hei ignition system has its own failures. So any one has some good variabel ignotion module replacement circuet who can work with an pick up coil? Or some thing that can control an singel darlington transistor variabel circuet? I hate this deam hei staff so I hoppe some one can help my to chose right components for the task some sort of chaneling system so I can programe spark frequency voltage amps manuali with out those anoying ic chips. I also have problems figuring out wire type because the lenght I face resistance problems. In the past I used potenciometer betwean pick up and ignition module didnt work how I hopped it wuld engine run crappy and fiered at exaust insted at compresion even tough engine started but run terribel.So simplified I need an angel degree about +/-20° phase shift before top dead center and after top dead center piston travel. Any way I dont reali care what to phase shift coil,pick up or module .Any thing wuld do just some one help my please .