Re: [[EE] Resistor power rating

I need to experiment a little.
Tune for maximum smoke as my compatriot used to say
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 780582
Derbyshire                eMail: [email protected]
*SK23 7ND          web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb> *



*Sent from my etch-a-sketch*


On Tue, 9 Dec 2025 at 13:09, Alan Pearce <[email protected]>
wrote:

> Just be careful though, I have had "concrete block" wirewound resistors
> smoke on me. I don't know exactly why but suspect it was something to do
> with peak current at switch on.
> The ones I refer to as "concrete block" are those in a 1" cross section
> ceramic package with a cermet mixture on on side where the element gets
> inserted.
>
>
> On Tue, 9 Dec 2025 at 08:55, David C Brown <[email protected]> wrote:
>
> > Thanks for that.   It seems that a 5w wirewound resistor wold easily meet
> > my requirements
> > __________________________________________
> > David C Brown
> > 43 Bings Road
> > Whaley Bridge
> > High Peak                           Phone: 01663 780582
> > Derbyshire                eMail: [email protected]
> > *SK23 7ND          web: www.bings-knowle.co.uk/dcb
> > <http://www.jb.man.ac.uk/~dcb> *
> >
> >
> >
> > *Sent from my etch-a-sketch*
> >
> >
> > On Mon, 8 Dec 2025 at 22:22, Clint Jay <[email protected]> wrote:
> >
> > > Vishay and Bourns both have info on their wesbites about selecting
> > > resistors for pulse load applications:
> > >
> > >
> > >
> >
> https://www.vishay.com/docs/48516/_ms9702509-2401-vishaychecklistpulseload.pdf
> > > https://www.bourns.com/products/resistors/pulse-power-resistors
> > >
> > > On Mon, 8 Dec 2025 at 19:32, Jason White <
> > > [email protected]>
> > > wrote:
> > >
> > > > vishay makes some nice pulse rated 2512's that have some graphs where
> > you
> > > > can look this up in
> > > >
> > > > On Mon, Dec 8, 2025 at 2:09 PM David VanHorn <[email protected]>
> > > wrote:
> > > >
> > > > > Normally, resistor power ratings assume 100% duty cycle, so 1/0.016
> > > would
> > > > > be a first approximation, but the part may not be capable of
> > > withstanding
> > > > > that much pulsed power.
> > > > > Unfortunately, the low duty cycle ratings are hard to find on most
> > > > > resistors.
> > > > >
> > > > >
> > > > > On Mon, Dec 8, 2025 at 11:37 AM David C Brown <[email protected]>
> > > > wrote:
> > > > >
> > > > > > I am planning to use a 2R2 resistor to limit the current to a
> > > solenoid
> > > > to
> > > > > > 6amps.
> > > > > > Ohms law says that the power dissipation is about 80watts.
> > > > > >
> > > > > > But the duration of the current pulse is only 16mS.   Does that
> > mean
> > > > > that I
> > > > > > can get away with a lower power rating and, if so, how much
> lower?
> > > > > > __________________________________________
> > > > > > David C Brown
> > > > > > 43 Bings Road
> > > > > > Whaley Bridge
> > > > > > High Peak                           Phone: 01663 780582
> > > > > > Derbyshire                eMail: [email protected]
> > > > > > *SK23 7ND          web: www.bings-knowle.co.uk/dcb
> > > > > > <http://www.jb.man.ac.uk/~dcb> *
> > > > > >
> > > > > >
> > > > > >
> > > > > > *Sent from my etch-a-sketch*
> > > > > > --
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> > > >
> > > > --
> > > > Jason White
> > > > --
> > > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
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> > >
> > >
> > > --
> > > Clint. M0UAW IO83
> > >
> > > *No trees were harmed in the sending of this mail. However, a large
> > number
> > > of electrons were greatly inconvenienced.*
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