How to slow down a 220V~ ventillator

[Zedman]

Hi,

I would like to set the speed of a 220V~ ventillator with a simple circuit
(no PWM, no MCU, no separate power supply), any ideas?

thanks,
Zed

 

[jorgito]

Hello Zedman,
Try a capacitor in series with the fan.

Best regards

 

[penrico]

Most fan have series inductors to reduce the speed. It's easy and safest

 

[Zedman]

thanks,

but what size of capacitor or inductor do i have to try?
How can I calculate it? it's 220V~ here with 50Hz.

Zed

 

[penrico]

First, you must know the current needed by your fan. It be getted by a multimeter.

Then, with these formulas you have:

XL = 2. PI . f . L
XC = 1 / (2 . PI . f . C)

Using the value of current needed, you have: R = V/I -> (220/I)

If you put then an XL or XC at same value of R you calculated, the voltage divider will be the half.

Vo = 220 . R / (R + XL) or Vo = 220 . R /(R+XC)

 

[Zedman]

I calculated an approx. 7 uF capacitor (@0.5A) to slow it
down to half. Will buy the nearest one.

Thanks

 

[penrico]

Be carefully with voltage (630V I recommend), and ESR, do not use electrolitic capacitors, try to put ceramic capacitors

 

[Desert Leo]

Zedman, try with serial diode with appropriate reverse voltage and forward current.