PWM Tutorial in HD

Afroman goes over the basics of PWM and shows you how to cheaply build a PWM circuit that can dim LEDs, control the speed of a motor, or control the power going to pretty much anything you want! Don't forget to vote 5!

Circuit diagrams at: http://afrotechmods.com/groovy/PWM_tutorial/PWM_tutorial.htm

Category:

Science & Technology

Tags:

• Pwm
• Circuit
• Electronics
• Dimmer
• Speed
• control
• Pulse
• Width
• Modulation

[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.

[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.

[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.

[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.

[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.

[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.

[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?