question about mosfet ratings

No, I did actually mean liquid CO2. I figured that if we were going to be impractical, we might as well go all the way. Ever seen any liquid CO2? I have, but that's a tale for another time.

As others have pointed out, the package is rated for 75 amps, not 280, and the data sheet (at least for the 280 amp TO-220 packaged IR part I looked up) is very clear about that: it calls it a 75A part in large print right up at the top of the data sheet. It's only when you get to the detailed specs table that they separate out the 280 amp rating for the silicon.

Cheers, Tom

Temperature rise is proportional to power. Power is proportional to the square of the current for a constant resistance. (75/280)^2 =

0.2679^2 = 0.0717, or as Spehro says, about 7%. I'm not sure where that 23% came from... and depending on the cycle time, for reliability you'd likely want to keep it well below 7%. 350 milliseconds "on" at 280 amps out of every five seconds would probably lead to rather rapid failure due to thermal cycling. You might be OK with 3.5 microseconds out of every 50, for a while.

Cheers, Tom

Hello Rich,

This one was a regular tranformer type and the amp was so small that it couldn't possibly deliver that kind of power for more than a second even if it were class-D.

It seem to be similar to horsepower ratings for cars, just not as extreme. My car has 130HP (sez the ads) and weighs about two tons. Yet it's acceleration isn't as much better as I'd expected when comparing it to a 7.5 ton truck I once drove that also had 130HP (but Diesel).

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Regards, Joerg

http://www.analogconsultants.com

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The damn bonding wires from the source lead to the die is a *lot* smaller, and most likely open up like a slow blow fuse. That 280 amps is not a rating, it is a theoretical maximum impulse (say *one* pulse, 1 microsecond long).

Sure It Can - Read the small letters in the spec: you just need to bolt the device securely to the surface of a m^3 of neutron star material immersed in liquid helium for cooling ;-)

When Marketing (or Management) speaks, professionals of several industries can unite in cynicsm and derision!

Because of "market segmentation":

Diesels have more torque to begin with. The turbo comes with intercooler and the gearbox for a truck is much better than it is for a car: If the gearbox/turbo-setup can track the engine torque- and efficiency-curves better, the truck can save fuel which goes towards profits by the business that use the truck - so the extra expense for the better kit makes sense to the buyer. ... And gives better acceleration.

The car just have to go under the price the market segment will accept, once it's out of the showroom the profit has been made and what happens later is irrelevant. So the care goes into optimising production costs and warranty repairs. Which you do not feel when you put your foot down.

PS:

At two metric tonnes *I* would never buy anything petrol-based; the certain way to financial ruin, divorce and more ruin when enraged ex. screw you over ;-)

Diesel's has the distinct advantage of being able to run on both heating oil and home-produced rape-seed oil - much "privately funded R&D" has gone into this here (DK) to the great annoyance of the IRS. You just have to "know" a local farmer of the right enterprising nature ... and most people would rather pay him than the Saudi's.

Hello Frithiof Andreas,

the

That's why I bought a car based on an older light-truck chassis. It's been through the paces and reliable.

It's different in the US. Diesel is expensive, not as available as in Europe and probably less good (smokes a lot). My car yields about 25mpg (probably about 10l/100km) which is quite good by US standards. In California you cannot buy most vehicles in a Diesel version because they aren't certified to our rather strict emission regulations.

and

him

Some people do that here as well. They use discarded oil from fast food places. Also some gasoline cars that can run on bio fuel.

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Regards, Joerg

http://www.analogconsultants.com

the

the

way

and

him

Kentucky Fried Chicken will clog your jets ;-)

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
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I love to cook with wine.      Sometimes I even put it in the food.

Hello Jim,

and

him

That's why we made these to help guide the unclogging process :-)

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Regards, Joerg

http://www.analogconsultants.com

"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

You can use a 2 - 3 micron filter to clean the oil before pouring it in your tank.

Used bio oil can be used direct, but you have to start off with normal diesel, so the injector thingummies are hot, then change over to bio gloop. If you stall the engine , when using bio gloop you may possibly gum up the injectors, which may be a problem. So, to stop the engine, you have to change back to regular diesel, to flush them tubes

The otherway is to treat the bio oil with methanol, which will separate the glycerine out, leaving real biodiesel, but on a small scale it seems to need a lot of heat, so I'm not sure if it is worth it, apart from the pleasure of annoying them Revenue/Tax folks

martin

I know we used to clean the oil in our molding machines by forcing it through a filter with a small hydraulic pump, fitted with a relief valve. After a week it cleaned up the oil quite well.

A co-worker tells me that a high thread-count pillowcase works just as well as a filter.

Michael

On Wed, 11 Oct 2006 12:26:05 +0200, Frithiof Andreas Jensen wrote in Msg.

If the situation in DK is the same as in D, the stuff that you get from the farmer is not his homemade rapeseed oil, but his subsidized tractor diesel. The Saudis get just the same.

Rapeseed oil is grossly overrated as a "bio-diesel" since its production costs too much energy and land. What has more future is bioethanol made from agricultural plant waste because it uses *all* (or a higher fraction of) the total biomass produced by sunlight and CO2.

Biodiesel (rapeseed oil) is pushed by the oil industry because it is better suited with their existing merchandise and infrastructure.

robert

No - used to be, but now there is dye in that stuff! The rapeseed oil is pressed and filtered with a machine first built by some enterprising machine shop and now widely copied. Old Citroen BX diesels are the favoured target.

Tax Efficiency beats *any* improvement possible in *any* other area - the government still wonders why growth is weak and investment lacking but that is because once one starts to move into the top tax brackets it becomes pointless busting one's arse working. The real gain comes from getting more goods out of less money.

The same goes for businesses: Once people are employed they become channels through which government can suck precious ressources out of one's business - so a lot of the work is done as one-off's by self-employed contractors or farmed out to web services (book keeping, inventory, shipping f.ex.).

Nobody wants to get stuck with employees unless it is absolutely unavoidable.

Sure - there is also farm subsidies to be had, the Oil industry also have an image* problem and politicians like to "be doing something"..

*) Maybe the "CO2 theory" is in for a fall: "Proceedings of the Royal Society A", 3. oktober; 'Experimental Evidence for the role of Ions in Particle Nucleation under Atmospheric Conditions'; Henrik Svensmark, Jens Olaf Pepke Pedersen, Nigel Marsh, Martin Enghoff og Ulrik Uggerhøj

fets are resistive devices and P=I*I*R

Bye. Jasen

I saw one that size 10 years ago, it did 240VAC to 120VAC conversion at upto 1000W. the case was mostly heatsink and the insides dominated by a toroid or two and and some TO220 shaped things. Anodised gold, made in USA I forget the brand.

Bye. Jasen

I've felt it slosh inside CO2 extinguishers... that must have been an impressive pressure window you saw the CO2 through.

Bye. Jasen

Hello Jasen,

With some of these you have to be careful. I got one from a guy who worked in Germany for a while and after moving back he gave it to me. All it was: A glorified dimmer! Had some little toroids in there to muffle the noise a bit. The engineer ran his radio off of it for years and I was amazed it survived.

--
Regards, Joerg

http://www.analogconsultants.com