Same 555 timer based PWM controlling a cheap box fan

In this short fragment you can hear the PWM induced noise as the cheap brushless DC fan speed decreases. The normal fan speed of this unit is much higher than the silent 120mm box fan I controlled in my previous movie. This fan is very powerful but will introduce vibrations, hence it is not my first choice for using all time to cool a telescope. It has a potent air flow though, hence it can be used to accelerate cool-down of the primary mirror before observing.

Category:

Science & Technology

Tags:

• PWM
• Pulse-width-modulation
• Electronics
• 555
• box-fan
• case-fan
• DC

[handsfreekvm]

Hello nice vid. did you make the PCB board yourself?

To get rid of the choppy sound during low duty cycles, you will need a higher frequency PWM signal. if you go higher in PWM frequency, 20Khz (above human hearing) it will eliminate any audible switching noise. so instead of (_|----|____|----|____) it would be (_|--|_|--|_|--|_) not to scale but basically the same average power during one x time frame but more pulses in that time frame.