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Fan dimmer

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Fahime

New Member
Hi,
I am making a fan dimmer like the attached file dim2.jpg
When dimmer is at low speeds, you can hear a noise in the fan. I think I need to add a series choke and a parallel capacitor like the attached file dim1.jpg but I do not know how to calculate their values. Could you please give me an idea?
 

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crutschow

Well-Known Member
Most Helpful Member
Well, I've done it myself and it sort of works, but the motor can be noisy due to the pulses from the dimmer. I don't know if there's much you can do to quiet that noise although a choke and capacitor might help.
 

MikeMl

Well-Known Member
Most Helpful Member
Raise the chopping frequency. At 50Hz or 60Hz (AC Phase control), the LC filter components will be bigger than the motor...
 

bountyhunter

Well-Known Member
Hi,
I am making a fan dimmer like the attached file dim2.jpg
When dimmer is at low speeds, you can hear a noise in the fan
That's because you are stalling it, and it doesn't like that. It can also make it get hot. I believe most modern ceiling fans use a split capacitor AC induction motor and speed is adjusted by switching in a different value of capacitor driving the secondary winding.
 
Last edited:

Boncuk

New Member
My design can drive up to 1.5KW motors without noise. It uses a mains synchronized trigger signal for the triac corrected for slip in the motor.

Boncuk
 

RODALCO

Well-Known Member
Try a 1.5 uF 400 Volts capacitor.

I have successfully used those in the standard 3 speed fan to make it 6 speed and obtain hereby the 3 low speeds which are perfect for a hot summers night when you don't want too much draught when reading a newspaper.

A bit of trial and error is needed here.
 

RODALCO

Well-Known Member
Don't even bother with a choke. Put a 1.5 µF Cap. in series with the motor and a mains rated bypass switch in parrallell with it.
 

Boncuk

New Member
It's a switch able to handle mains voltage and the load current of the fan without burning up.
 

RODALCO

Well-Known Member
Thanks Boncuk, you were faster than me in your reply.
 

Dick Cappels

Active Member
I would like to see the circuit that actually slows down the fan without making a lot of smoke or noise. It seems that it would take an awful lot of filtering to remove the harmonics which are responsible for the additional noise, and if that were applied to the original circuit, wouldn't the currents flowing in the high Q resonant circuit prevent the triac from commutating off?

Anybody who has really solved this, please post here because I want to make one for my own use.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I would like to see the circuit that actually slows down the fan without making a lot of smoke or noise. It seems that it would take an awful lot of filtering to remove the harmonics which are responsible for the additional noise, and if that were applied to the original circuit, wouldn't the currents flowing in the high Q resonant circuit prevent the triac from commutating off?

Anybody who has really solved this, please post here because I want to make one for my own use.

As we've said, this isn't the way you speed control a fan - they don't use universal motors, and aren't suitable for phase control, filters or otherwise.
 

RODALCO

Well-Known Member
If time allowes over the weekend I make a short video of my fan with the audio sound and will put it on YouTube.

I maintain to keep an idea simple, especially for a humble fan.

But you can of course fit a commercially built frequency inverter to have full speed control from 0 to 150%. But those costs will outweigh the cost of a $20 fan.
 

RODALCO

Well-Known Member
6 speed fan

As said, I managed to get some time to make a clip on YouTube.
I forgot about the music but it enhances the video anyway.

That fan is not growling at low speeds and is very quite.

Just watch the video, the stroboscopic effect of the blades is quite cool.

YouTube - 6 Speed cooling fan
 

RODALCO

Well-Known Member
:)

Yes, well spotted audioguru,

:)

It didn't click to me to give it a brush prior to taking the video.

I said it was a quick clip.

But now I'm vacuuming the house and will give it a clean in the next 5 minutes.
 

RODALCO

Well-Known Member
Well it took 24 hours but the fan is clean now.
 
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