Fan Voltage Regulator

Does it need to be galvanically isolated from the incoming mains for safety reasons? If so then there are plenty of lumps of equipment available in the Maplin, Farnell and RS catalogues (usual disclaimer), and inexpensively too.

Hello fireball

The simple answer is: Yes, but the modifications would cost much more than buying a electronic fan voltage regulator made for 24 volt dc control.

Take the advice from PWSlack above, and get one for the correct voltage.

Kind Regards....

Hi, you know that things meant for ac may or may not be directly used on DC voltage.

Fan regulator consists of resistive element with a knob that can be placed manually at different position of that resistor to vary the resistance.

AC voltage is used in driving the fan rotor, that consists of its own resistance & fan regulator is nothing but resistance that is used to vary the resistance of rotor which in turn changes the speed of the rotor. So fan regulator is just an additional resistor used in parallel or series with rotor to change the rotational speed of fan.

A fan regulator can be used for 24V dc control only if its internal resistance can bear that much DC voltage & heat due to continuous operation on 24V. So the thing that you can do is : test the regulator on dc voltage of 24 volt, if it works properly then it can surely be used to control 24V dc voltage.

Hello Deepti Saini

fireball has not advised us of the type of regulator he possesses, except: <"....general electronic fan voltage regulator (used for 230V AC)....">, without a specific make/model etc.

fireball has also not advised of the type of motor in his proposed DC fan, except it is 24 Volt.

Thus nobody may properly advise fireball because insufficient information has been provide to make a correct reply.

Your statement: <"....Fan regulator consists of resistive element with a knob that can be placed manually at different position of that resistor to vary the resistance...."> is not necessarily true, as there are other types of fan speed controllers, and fireball has stated the one he has is : <"....general electronic fan voltage regulator (used for 230V AC)...."> which is not the resistive type you mention.

That's why PWSlack and myself gave the replies as above.

I trust you appreciate why I reply to your Post.

kind Regards....

Hello Sparkstation,

As now Fireball has already mentioned, I also wanted to tell you that he didn't describe at all about any "24V dc fan" that you were assuming fireball want to control. And one more thing I just want to tell you that a general electonic fan voltage regulator is always made of a simple resistor whose knob controls the voltage to fan, & for any other electronic fan voltage regulator, specification of type of model is required.

Now leaving all these issues I think we should try to provide the solution to SCR controlled Fan voltage regulator mentioned now by Fireball.

Hello Deepti Saini

<"....And one more thing I just want to tell you that a general electonic fan voltage regulator is always made of a simple resistor whose knob controls the voltage to fan, & for any other electronic fan voltage regulator, specification of type of model is required....">

I don't really wish to contradict you, but you are quite incorrect in that statement.

if you intend to give electrical or other advice to others, please ensure you state the correct facts.

There are many "general" ways of controlling the fan speed electronically, other than with a simple potentiometer (<"....variable resistor whose knob.....">)

However, I do realise that in your location, and in your experience, you may have never seen any other type of fan speed controller.

Kind Regards....

Hi did you notice , he meant Electronic Fan speed regulator !

Yeh I have noticed that, General Electronic Fan Voltage Regulator is the device which actuallly controls the speed of fan by regulating the votage.

Hi !

Sorry for misconceptualize!

I mean an electronic fan voltage regulator which may be consist of SCRs or like(i don't know exactly).

and i wish to control a 3.3 volt LED supplied with 24v dc.

Does it possibe with electronic fan regulator?

Thanks & regards!

Hi agian!

I probably got the answer.

SCR and TRIACs remains ON after it gets fired once by its gate terminal.

So it can not be worked to control DC supply to the load using general fan regulator ciruit.

Thanks for all the interestive response!

Dear Friend !

The Fan Regulator available in market for used for 230V or 110V AC uses a Triac & the Regulating Control is a variable Resistor & is the part of Triac's Control-Voltage to fire @ varying angles. [A capacitor in series with the variable Resistor ]. Gate Pulses on each 1/2 cycle for Triac.

In a DC Cct it cannot generate varying voltage for control of Triac's angle of fire.

Kind regards !!!!!