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From: quiettechblue on 16 Jul 2010 02:04
On Tue, 13 Jul 2010 07:48:48 -0700, Joerg <invalid(a)invalid.invalid>
wrote:

>John Larkin wrote:
>> On Tue, 13 Jul 2010 06:19:55 -0500, "Tim Williams"
>> <tmoranwms(a)charter.net> wrote:
>>
>>> http://www.fairchildsemi.com/ds/FG%2FFGA30N120FTD.pdf
>>>
>>> Maximum collector current 60A at 25C. I don't see any condition, taking a reasonable guess at Vce(sat) at max Tj, where this could possibly dissipate anywhere near the power rating of 339W (also at Tc = 25C). In fact, the typical output characteristics show it should be closer to Vcesat = 3V, Ic = 120A, Vg = 15V. So why pick 60A?
>>>
>>> More BS? What's the real rating?
>>
>> I'd go for the headline: 30 amps. That's achievable, without a lot of
>> switching losses or water-cooled diamond heat sinks. The 339 watts is
>> absurd.
>>
>>
>>> Buy from someone else? Ha, no one else even has honest ratings...
>>>
>>
>> Looks like everybody has to keep up with IR. They should add to "Abs
>> max ratings"
>>
>> MAXIMUM LIES 12 typ
>>
>
>It can get worse. I saw an audio amp in a blister pack, IIRC at a
>Walmart. Said 1000 watts PMPO on the label and the power supply was a
>wall wart ...

I remeber outrageous PMPO ratings from well over 40 years ago.
Something not much bigger than a small 3-1/2 external drive case,
rated at 100 W per channel stereo including power supplies. Middle to
late 1960s. They're baack.
From: Tim Williams on 16 Jul 2010 07:43
<quiettechblue(a)yahoo.com> wrote in message news:tisv36ltdo6miuiqpqm81cu41d9j57vv07(a)4ax.com...
> This is a kind of cyclical thing in electronics. Specsmanship gets
> quoting ever more unreasonable values driven by things like "infinite
> heat sinks". Eventually there are too few old dogs to keep the punks
> from believing the spurious ratings. Failures and then lawsuits
> follow like Nemisis following Hubris. Then the specs get more
> realistic again for a while, then sales critters insist on bending
> them again. There is a deficit of memory in the beauracracies that
> causes this oscillation.

Hmm, I wonder if that oscillation is in phase with the "component shortage" oscillation.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
From: John Larkin on 16 Jul 2010 10:06
On Fri, 16 Jul 2010 06:43:01 -0500, "Tim Williams"
<tmoranwms(a)charter.net> wrote:

><quiettechblue(a)yahoo.com> wrote in message news:tisv36ltdo6miuiqpqm81cu41d9j57vv07(a)4ax.com...
>> This is a kind of cyclical thing in electronics. Specsmanship gets
>> quoting ever more unreasonable values driven by things like "infinite
>> heat sinks". Eventually there are too few old dogs to keep the punks
>> from believing the spurious ratings. Failures and then lawsuits
>> follow like Nemisis following Hubris. Then the specs get more
>> realistic again for a while, then sales critters insist on bending
>> them again. There is a deficit of memory in the beauracracies that
>> causes this oscillation.
>
>Hmm, I wonder if that oscillation is in phase with the "component shortage" oscillation.
>
>Tim

The oscillation is like the stock market, caused by the same
differential time constants of human greed and fear.

We are now seriously into yet another silicon fab shortage. Lead times
are skyrocketing into the triple-digits-of-weeks, people are
multiple-ordering, brokers and counterfeiters are cashing in, the
usual cycle.

John

From: keithw86 on 16 Jul 2010 10:18
On Jul 16, 9:06 am, John Larkin
<jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote:
> On Fri, 16 Jul 2010 06:43:01 -0500, "Tim Williams"
>
> <tmoran...(a)charter.net> wrote:
> ><quiettechb...(a)yahoo.com> wrote in messagenews:tisv36ltdo6miuiqpqm81cu41d9j57vv07(a)4ax.com...
> >> This is a kind of cyclical thing in electronics.  Specsmanship gets
> >> quoting ever more unreasonable values driven by things like "infinite
> >> heat sinks".  Eventually there are too few old dogs to keep the punks
> >> from believing the spurious ratings.  Failures and then lawsuits
> >> follow like Nemisis following Hubris.  Then the specs get more
> >> realistic again for a while, then sales critters insist on bending
> >> them again.  There is a deficit of memory in the beauracracies that
> >> causes this oscillation.
>
> >Hmm, I wonder if that oscillation is in phase with the "component shortage" oscillation.
>
> >Tim
>
> The oscillation is like the stock market, caused by the same
> differential time constants of human greed and fear.
>
> We are now seriously into yet another silicon fab shortage. Lead times
> are skyrocketing into the triple-digits-of-weeks, people are
> multiple-ordering, brokers and counterfeiters are cashing in, the
> usual cycle.

The difference is that this time the finger is easy to point; ==>
Obama.

From: Tim Williams on 16 Jul 2010 10:36
"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message news:plp0461ijha67i94udqotl2smm6dii3b06(a)4ax.com...
> We are now seriously into yet another silicon fab shortage. Lead times
> are skyrocketing into the triple-digits-of-weeks, people are
> multiple-ordering, brokers and counterfeiters are cashing in, the
> usual cycle.

Fortunately, there are still large stockpiles of common parts, like 2N3904s and LM393s. That's fine for me, if not for people who need fancy things.

I'm more concerned about finding capacitors suitable for induction heater use. I found two series, by Epcos, which look good. One has shown the same lead time for years, I haven't bought any since the first tank cap;
http://webpages.charter.net/dawill/tmoranwms/Elec_CapBank.html
the other is gone entirely (in fact, I just bought Digikey's remaining stock). And these are just regular MKPs. The other cheap caps, like Illinois Capacitor or BC Components' MKP lines, have way too much ESR.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
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