Drive 12V Relay -- END IT
Archiver
Posts: 46,084
This thread has gotten out of hand, and it's off subject to begin with. Haven't
enough experts chimed in to get the point across: don't drive an AC device with
DC???
Friend, you're wrong on this one. Sorry. Let's move on.
Clark Hughes
Leroy Hall wrote:
>
> But I thought the point of the whole matter was that it is a 'HOT'
> idea! Would a small resistor, sized appropriately, be a bad idea as
> well?
Yes, it's a bad idea. Burning power for no good reason.
I would think the DC current should be reduced to the same value
> as the RMS AC current as the coil would normally use?
No. Read the post below to develop an understanding of the difference between
DC resistance and impedance.
> Leroy
>
> Rob wrote:
> >
> > The "resistance" of an AC coil is if fact the term impedance, denoted by
> > the character Z. Z is a function of the DC resistance and the reactance
> > of the coil XL. XL is derived from the term 2PIfl, where pi= 3.141
> > (approx) f is the frequency of the AC supply, and l = is the inductance
> > of the coil.
> >
> > Z= SQR (XL^2 * R^2).
> >
> > Typically in a coil designed for AC use R is small and XL is large (this
> > determines "Q" factor, but we won't go there). And that is why using AC
> > coils on DC is not a hot idea.
> >
> > Rob
> >
enough experts chimed in to get the point across: don't drive an AC device with
DC???
Friend, you're wrong on this one. Sorry. Let's move on.
Clark Hughes
Leroy Hall wrote:
>
> But I thought the point of the whole matter was that it is a 'HOT'
> idea! Would a small resistor, sized appropriately, be a bad idea as
> well?
Yes, it's a bad idea. Burning power for no good reason.
I would think the DC current should be reduced to the same value
> as the RMS AC current as the coil would normally use?
No. Read the post below to develop an understanding of the difference between
DC resistance and impedance.
> Leroy
>
> Rob wrote:
> >
> > The "resistance" of an AC coil is if fact the term impedance, denoted by
> > the character Z. Z is a function of the DC resistance and the reactance
> > of the coil XL. XL is derived from the term 2PIfl, where pi= 3.141
> > (approx) f is the frequency of the AC supply, and l = is the inductance
> > of the coil.
> >
> > Z= SQR (XL^2 * R^2).
> >
> > Typically in a coil designed for AC use R is small and XL is large (this
> > determines "Q" factor, but we won't go there). And that is why using AC
> > coils on DC is not a hot idea.
> >
> > Rob
> >