Very simple PWM with 555...Modulate every thing

Note:Any one can ask me for help.Don't comment me on my spelling and grammar.......Because my mother language isn't english.OK LETS GO

and also plz plz rate my instructable well



Hi every one.Today i'll show you how to make a PWM(pulse width modulation) out of a very famous chip 555(lm,ne any one will do) with some other parts offcourse.This is really simple and it is very handy if you want to control your leds,light bulb,servo motor or dc motor(brushless also works).
My pwm can only change the duty cyle from 10% to 90% it cant do nothing more!

Step 1 What Is PWM

Pulse-width modulation (PWM) of a signal or power source involves the modulation of its duty cycle, to either convey information over a communications channel or control the amount of power sent to a load.The simplest way to generate a PWM signal is the intersective method, which requires only a sawtooth or a triangle waveform (easily generated using a simple oscillator) and a comparator. When the value of the reference signal (the green sine wave in figure 2) is more than the modulation waveform (blue), the PWM signal (magenta) is in the high state, otherwise it is in the low state.But in my pwm I will not use comparator.

Comments

[IronWill]

Good job.
Would you be so kind as to please tell me the title of the textbook you are referencing?
it looks like a really useful book.

[jhaneyzz]

I think I get it all until it comes to connecting the TIP31. I am trying to dim a 12v lamp. Low voltage bulbs used along walkways.

I tried to connect the power transistor based upon what little I could see in the picture, and I ended up frying the 555.

Could someone help me figure out the correct schematic. It would seem to differ significantly from the "magazine article" diagram, given the picture shows a power transistor as well as a 2200uF cap!

Help!

[igorpark]

jhaneyzz,

What kind of power transistor are you using? Is it a FET? I believe the problem you are experiencing is due to high current during the power transistor turn-on.

This is most likely exceeding the drive capabilities of the 555 and is frying the chip.

I believe the solution for you (if you are using a FET) is a proper mosfet driver IC. The PWM signal from the 555 would hook into the driver, and the driver would control your FET.

An additional benefit of dedicated drivers is that a faster on/off transition decreases switching losses, and thus reduces the heat on the FET. I recommend taking a look at Linear Technology parts, as their data sheets are excellent, and their free circuit simulator (LTSpice) is also very good.

This IC: http://www.linear.com/product/LTC4441 Might be close to what you need...

Good luck!

[jhaneyzz]

I'm using a TIP32 just like in the picture. This is a standard pop voltage regulator.

But I don't see any guidance in how to place this in the schematic.

[boredomandi]

you need to control the current not the voltage with leds! check onsemi part NSI45030AT, the data sheet explains it very well. once you have a maximum current then(say 30 mA) use the 555 to change the voltage. and shams your engish is just fine!

[camservo]

Any suggestion on how to modify this to be used as a dimmer circuit for the backlight on an LED monitor? I've measured the LEDs at 32v. I'm still learning electronics, but I've seen dimmable monitors go for 4000 dollars!

[shams]

Actually its kind a complicated...because leds on led monitors are in matrix so u cant dimm them without complicated digital circuit....

[rakesh91118]

Dear I have made PWM with 555, and its working good as power supply m using 12V 1Amp. adapter available in market for CCTV cameras it's around Rs.75 to Rs125/- only. I have made this 39 LEDs (3LED in series with 47E resistance in 13 parallel lines ) in 1" PVC baton used in Electric wire fitting on walls. My Qus. is if we glow the LED array on full brightness with PWM, is it will long lasting. Becoz if we run array with more current, the LEDs go burn or go dim after few days. I set it on 9.5V (3 leds=3.1vX3Leds=9.3V) But its light is not much bright at this level. I have used white LEDs Ratting 3 to 3.2V and 10ma. Pls suggest on what level of voltage I have to set for long life and good bright light.

[shams]

yes it might be....bt leds are very sensitive to current changes...u may need a current regulator..to make it longer lasting....or you have to use resistors with but efficiency will be low

[scraptopower]

Is it possible to wire this up with a NPN transistor rather than a PNP ? I want to drive a 1A 12V motor. Thanks,

[hubi]

This is a cool circuit for dc motor speed regulation, i have built it and tested with a dremel like tool.

Tipp for your next plan, you can use 2 *555.
The first one will run in astable mode the 2nd one is a voltag econtrolled monostble, triggered by the first one.
A nice Tool for this is 555timer pro from http://www.schematica.com/
for your purpose the free demo would be sufficient.

[shams]

Thanks.I will consider using it

[BG79]

Hello. Is there a way to make this PWM output ~ 500mAh? I´m trying to use it into a superled, but 200mAh is too low. Tkz.

[shams]

yeah get a higher power rated transistor

[moogbeatz99]

will a 12v pwm dimmer circuit for LED's run off of 9volts? is it just the limit, or what it requires?

[shams]

I didnt get ur question....can u break ur Q down ?

[moogbeatz99]

does a 12 volt rated PWM need 12 volts to run, or is that the maximum amount of voltage it can handle. I already figured it out pretty much, the one i wanted to use needed 12 volts to run in the first place, not a maximum of 12 volts.

[shams]

actually you can use any voltage as long as the voltage across the main pwn module is in the limit of 555..and those transistor/mosfets.I would suggest to use linear voltage regulator for the pwm module so that what ever voltage you use your frequency and effective range will be the same bt for you transistor you dont need regulator because you can use any voltege under the limit of that transistor/mosfet

and yeah you can run this one as low as 5v...(Cmos 555 goes way too lower..mine one is a cmos)

[shouldawoulda]

Hello, your post said I could ask,,here goes!   I am new to electronics though of middle age,,"GUESS",,  I am wanting to pulse modulate my service meter to my home to reduce cosumption to EVERYTHING,, is this possible or am I going to have to cut my power line from my "Cap Rock power Company" to eliminate there constant greedy grasp to my wallet?

[seabeepirate]

If you weren't new to electronics I might suggest that you design a device to do this. As Shams says you can't modulate AC but you could rectify your AC to DC to charge a large battery bank and then build yourself an adjustable inverter. Basically you'd build a giant uninteruptable power supply. To buy one for your entire home would likely cost a small fortune but you might be able to build one yourself much cheaper. I don't think that's a simple project though. So I guess the short and sweet answer is still no. At least it would be for me... I'm lazy and that's a lot of work haha!

[shams]

no you cant pwm AC...sorry bro...its impossible...only DC

[snowluck2345]

you actualy can, but you have to get the phases to stay in tuned, which is harder than dc where you done have phases.

[shams]

nope it cant be done.Because pulse modulation's frequency  will cause intefierence in your AC frequency thus you wont get the rated voltage and power ....actually it will pump more voltage to your electronic equipment because of high frequency...and smoke every thing

[hubi]

Sorry,
but this is onlythe half story,
it is possible to use PWM on AC, but it isn´t that easy, the PWM Frequency has to be high enough, synchronized to AC and you need special switch, since you can´t use a mosfet to switch AC. A Mosfet in a bridge amplifier from + to - output and the ~ connected in series to supply and load should do.

[Dantex]

I found out if you want led dimmer with it in current schematics at half-turn potentiometer led will flash
that can be filtered with capacitor, but it must bi bigger than 5000uF, so it is impractical
just replace capacitor with a lower value (10nF worked great for me), or just remove it

[girrrrrrr2]

Could someone post me a pic of this soldered up and off the circut board? it would help me alot.

[shams]

okay i'll

[amando96]

i made one this morning :) is it possible to wire it to a servo controler do make an ESC? or just wire a MOSFET to a servo controller?

[shams]

wire the mosfet with servo....

[JTreehorn]

I think your English is better that a lot of people who grew up with it.

[shams]

Thanks man.....

[Silvion]

Hey Man,

Thanks for your tutorial, really helpful!

[shams]

you are wellcome....I will come again with more usefull instructables soon !...

[Silvion]

Just thought of a question.. When you turn the pot right down, the fan doesn't spin. What happens to the power? will it 'burn' it? Would that require a heat sink on it?

[shams]

it just cuts of the transistor to switch of state ....so no burn !!......If you are using a mosfet then you dont need any heat sink.....

[CSharpDev]

This is great! Just the explanation I was looking for. I looked around, and it looked very complex. This is simple and to the point.

[shams]

Thanks man...its from wikipedia..xp

[lenovostart]

thank you for your ideea...i i am on the begining on electronic road and i need a few tips from you if you can:
1. how can i build a source of 12v by my own?
2.and can you send me the original material from were you take this project?


sorry that my english is not so good

[shams]

dont be sorry bro.....even my english not good at all.....You can use the pc atx power supply as a stable and high current 12 volt supply.....or use a wallwart charger of 14vdc or 15 vdc and use a linear regulator like LM7812..but they are rated only 1amp.....and what do actually mean by original material ?

[R0B0_Ninja]

Here is a tip. Use high value resistors and low value capacitors. This will make the circuit less expensive and more low-power.