[sdiy] How to predict a transformer's current capability?

[Jaco Sloof]

Ok final question then; 
(sorry 4 al the stupid questions!

(and then you guys say that there is no such thin as a stupid
question, just stupiud answers, but i think im not really up to speed
here... i just took the function of a transformer for granted, but i
dont even really know how they function, even when i bui8lt my own
electromotors... whahaha!)

final question:
do the mounting holes affect the effectiveness of the transformer,
e.a: will maximum performance/stability raise if there were NO holes
in the laminated core, or if it was'nt laminated, (with alternately
precautions to prevent magnetic field (mf?) leakage?)


Thanx guys for filling me in so far... this list is really
educational, AND practical too!


<status on my ASM-1: no progress yet, due to psu-design)
<ok better then, status on psu-design:
-PCB made, still gathering components, but its looking good
-made a spice sim at a friends house, turns out its gonna be 650-700
mA of current, really stable (10-30 mV ripple), 
or 1.5 A (30-80 mV ripple) >

(am i crazy, designing my own voltage regulator out of discrete
components?)
--- John L Marshall <john.l.marshall at gte.net> wrote:
> Mounting holes are cool. The gap of concern is across the magnetic
> path.
> Typical power transformers have primary and secondary winding on a
> single
> bobbin. E-laminations are alternated through each end of the bobbin
> and then
> meet an I-lamination. There is one magnetic path through the
> windings and
> two magnetic paths around the outside where the mounting holes are.
> Least
> flux densitiy in the corners of the rectangular core.
> 
> ----- Original Message -----
> From: Jaco Sloof <jacosloof at yahoo.com>
> To: SynthDIYmailinglist <synth-diy at dropmix.xs4all.nl>
> Sent: Monday, December 24, 2001 11:42 AM
> Subject: Re: [sdiy] How to predict a transformer's current
> capability?
> 
> 
> > Hmm, gaps in the core...
> >
> > This concerns me a little bit, because:
> >
> > I'm still constructing my power supply, and
> > the transformer HAS gaps, as in; mounting holes to screw it
> > to the chassis, THROUGH the core...
> >
> > Is this Bad?
> > (hole diameter is 4.5 mm, that on each corner thus 4 holes...)
> >
> > Rrrrr, i'm getting saturating shivers here, with lots a
> background
> > noise...
> >
> > --- harry bissell <paia2720 at yahoo.com> wrote:
> > > You should be able to detect core saturation by
> > > watching the current very carefully... as saturation
> > > approaches the current increases very quickly... a
> > > knee
> > > similar to diode conduction (but going the other
> > > way...
> > > bigger!)
> > >
> > > Another way is to use a "telephone pickup coil" to
> > > listen to the hum (flux leakage) around the
> > > transformer. When the core saturates, the magnetic
> > > field will grow in the air surrounding the core.
> > >
> > > This will also identify transformers that by design
> > > or mistake, have substantial gaps in the core (usually
> > > a bad thing...)
> > >
> > > H^) harry
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Send your FREE holiday greetings online!
> > http://greetings.yahoo.com
> 


__________________________________________________
Do You Yahoo!?
Send your FREE holiday greetings online!
http://greetings.yahoo.com