[TowerTalk] Re: Carbon Resistors Beverage Terminations
Stan or Patricia Griffiths
w7ni@easystreet.com
Mon, 11 Feb 2002 16:42:22 -0800
Hi Don,
You must have been absent from class on the day they taught Ohms Law. I have
NO IDEA where you ever got the notion that the power rating of a string
resistors or a parallel combination is equal to only the power rating of the
lowest single resistor. Absolutely not true. Each resistor in the network
will dissipate power in inverse proportion to its resistance. If it is a
series string of identical values, like 10 each 47 Ohm resistors, each one
will dissiate 1 tenth of the total power. Ten half watt resistors can EACH
dissipate a half watt, or 5 watts total. Two 1000 Ohm resistors in parallel
(or any other identical value for two parallel resistors) will each dissipate
equal power. If the resistors are rated at 2 Watts each, then the parallel
combination will dissipate 4 Watts.
Stan
w7ni@easystreet.com
Don Havlicek wrote:
> Comments inserted below:
>
> Stan or Patricia Griffiths wrote:
> >
> > Hi Bob,
> >
> > Thanks for the info.
> >
> > Two parallel 1K, 2 watt resistors would give you 500 ohms at
> > 4 watts . . .
>
> YES
>
> > A series string of ten 47 Ohm, 1/2 watt would give you 470
> > Ohms at 5 watts.
>
> NO .. the power rating will still be 1/2 WATT !
>
> >
> > A series string of 220 Ohms and 270 Ohms, both 2 watts,
> > would give you 490 Ohms at 4 watts.
>
> NO .. the power rating will be 2 WATTS
>
> Power rating of a series string is the same as the LESSER/LEAST powered
> element.
>
> Don - N8DE
>
> >
> > I am sure I can come up with some of these combinations if
> > anyone needs them. How about $2 per set plus postage?
> >
> > Stan
> > w7ni@easystreet.com
> >
> > Robert Shohet wrote:
> >
> > > HI Steve,
> > >
> > > How about (approximately) 500 ohms and 1 - 5 watts?
> > >
> > > 73
> > >
> > > Bob KQ2M
> >
> > ________________________________________________________________________
> > Where do you get ICE bandpass filters & beverage matching boxes? The
> > same place that pays for the hosting of this list: The eHam Store.
> > Order online at http://store.eham.net.
> > -----------------------------------------------------------------------
> >
> > -----
> > FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> > Submissions: towertalk@contesting.com
> > Administrative requests: towertalk-REQUEST@contesting.com
> > Problems: owner-towertalk@contesting.com
________________________________________________________________________
Where do you get ICE bandpass filters & beverage matching boxes? The
same place that pays for the hosting of this list: The eHam Store.
Order online at http://store.eham.net.
-----------------------------------------------------------------------
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com