Super Easy 555 Timer PWM Generator

Just a quick and simple circuit you can build for pocket change to create a pwm signal!

Tune in for the next video in which we modify the circuit a bit to make it handle an actual load!

Thanks for watching!

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[talideon]

There's something missing from the circuit diagram, and I figure I should mention it just in case: you really want to have a flyback diode over the motor, as it's an inductive load, and without one, you could end up with a spike that would fry the other components when the motor spins down, causing the magnetic field to collapse and its energy to discharge. The flyback diode gives an alternative route for the current back through the motor, so it doesn't go back into the 555, &c.

[mikelunsford]

Hahaha..I just did this and my scope picked it rt up, I adjusted the variable resistor and it smoothed rt out. I showed my son how brilliant I am then he saw my phone and the video. Lol .. now I've got to learn how to use my scope. It says 200mhz. It's pretty old scope but it's a beauty. CRT is brilliant. Thx for the video

[bikefarmtaiwan]

This is a great channel :) Such an accessible way to explain electronics - gives a real fundamental explanation for basic circuits - exactly what is needed!

[GeorgeJFW]

This is what you were talking about!! This is alot cheaper and simpler then a NANO!! Dang now I gotta order a bunch of these

[power]

Nice explanation.liked the way you tested the variation in output using different components.keep up👍

[sageand]

Shocked when only seeing 3K subs. Very well done video

[vincentrobinette]

1n4001 diodes are standard recovery power diodes. the problem with these diodes, is that when they are reverse biased, there is a tail current before the diode quits conducting, an effect similar to a capacitor in parallel with it. I would suggest switching diodes, like 1N4148. another thing to try, would be schottky diodes, like 1N5819, which have much less forward voltage drop. The switching diodes have a negligible current tail, and the schottky doesn't have ANY current tail, though, it does have about 100 pico farads of junction capacitance. This video makes me want to get a 555 timer, and play with it again. I haven't touched one in almost 20 years!

[horstigerhorstiger]

the frequency doesn't actually change. It's just the proportion between on and off time that's changing. It actually stays around 500Hz and if its completly on it changes because of the frequency detection of the oscilloscope is irritated.

[tedbastwock]

This is a good demonstration. Thank you for sharing it.

[GhostsOfSparta]

Frequency range is very small due to 1k resistor, changing which does change duty cycle along with frequency.
I tried one 555 to generate pulse and other in mono-stable for duty cycle. But both need to be calibrated.
In the end I used TL494 IC, it is also simple and allows changing duty cycle by controlling voltage.

[frankowalker]

Very interesting, I'll have a go at this. Thank you.

[nsummy]

Thank you for this. I’m pretty new to circuits and have been using microcontrollers for pwm. I have read about using 555 timers but like you said, looks kind of daunting when you are new. The biggest reason I want to get away from the microcontroller is the boot up time. If I want to use a dimmer for example it’s not instantly on unless the mc is already powered.

I have also read about another chip that is designed specifically for this: ltc6992, though it seems to be sold out everywhere. It’s more expensive but simpler. Once the chip shortage is over you should make a video with it :)

[gordselectronicshobby]

Have you checked the output of your power supply with the scope? I ask because the Jitter of some of the wave forms seen could be coming from the power supply. Using batteries or Linear would be best. Buck or Boost convertor power supplies cause Jitter.

[mondude]

Good information! I am curious to know if yours had a audible frequency sound? Mine has a low frequency buzz sound and so I was wondering if that is normal, it does work great though. Thanks

[E-BikingAdventures]

Note. If you are using the 5% or 10% tolorance resistors, then 220 ohms will be red, red, brown, silver or gold.

[meax]

Nice video, can I use this circuit to control servo motor?

[TengizAdamashvili]

does it have to be ceramic capacitors? and those exact values? what if they're different?

[Bassman]

Hi, Is that a 0 to +12v pp i.e. all in the positive domain? Or is it -6v to +6v pp, i.e. half negative and half positive? Thanks for the video.

[alchemy]

I was wondering how does the duty cycle can be changed not by knob (i.e. potentiomter) but by those system that has push buttons. How does the push buttons change the value of applied voltage? One push button increase and the other push button decrease the voltage.

[gkdresden]

The frequency change can be avoided if you use a constant current regime for charging / discharging of the capacitor. I have developed a special circuit design for a voltage controlled PWM generator based on a TLC556 (2 timers in 1 device). This circuit uses only two additional components, a constant current diode E-101 (0.1 mA, min voltage drop <=0.5 V) and a capacitor. The rest is only wire connections. And it works great over the whole range of operating voltages and up to 250 kHz PWM frequency.

The low frequency of 500 Hz is only a thing of the resistors / capacitors you've chosen. You can easily go to 100 kHz with this circuit (even with the NE555) and therefore much beyound the microcontrollers abilities. For motor control you can choose also lower frequencies of down to 100 Hz or higher than 20 kHz. The lower frequencies give a nice engine sound. The higher ones are inaudible.

The spikes of rectangular oscillations are no artefact. The mathematical superposition of harmonic functions of a rectangular oscillation has spikes. This is no problem of real device behavior. They grow very rapidly the more harmonic orders you take. The ideal rectangular oscillation has spikes of infinite height for a duration going to zero. The reality damps the spikes to a hight and duration according to the slew rate of real devices.