[sdiy] 12vdc to 12v ac converter

Seb Francis seb at burnit.co.uk
Tue Sep 4 01:47:00 CEST 2007

Hi Rig,

Any ideas you can give me would be much appreciated.

I'm not sure of the exact type of motor - it is an extractor fan for a 
domestic shower.  It is a 'low voltage' type designed to run from a step 
down transformer.  However I want to use it in a vehicle and so have 
only 12VDC available, not 12VAC.

The fan is rated 12VAC 20VA 50Hz.  In UK 50Hz is the mains frequency but 
this isn't important - I don't care what speed it runs as long as it 
blows steam out of the shower!

Every parameter is really non-critical - even if it gets a bit less that 
12VAC RMS I think it's not going to matter as long as the fan turns.

Hopefully as you say the inductance of the motor itself will help smooth 
the output, keeping the circuit simple.  The closest thing I have seen 
so far is this:
(I am thinking the motor can be connected in place of L1 and T1)


bill bigrig wrote:
> Howdy,
>  In the book 'Electric Motors and Control Techiniques
> are many schematics for motor speed ontrol. One uses
> vrying square wave pulses in the shape of a sine wave
> with different pulse widths depending on the phase of
> the signal. there are many other controls that output
> square waves stating that the induction of the motor
> will smooth them out. What kind of motoer are you
> controlling? Is it a series motor/ Split phsae,
> synchronous, shaded pole, etc? If  know what kind of
> motor you are controllng, I can probably look it up
> and give you the best way to set it up,(according to
> the book).
> rig
> ____________________________________________________________________________________
> Boardwalk for $500? In 2007? Ha! Play Monopoly Here and Now (it's updated for today's economy) at Yahoo! Games.
> http://get.games.yahoo.com/proddesc?gamekey=monopolyherenow  
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy

More information about the Synth-diy mailing list