Thick film resistor

These are cool, thick film on porcelanized steel.

They handle enormous transient power peaks.

$23 apiece, wow.

Cheers

Phil Hobbs

They only cost us $19!

We're using them to replace a military-type (bolt-down gold aluminum block) 250 watt wirewound power resistor that was failing from pulsed loads.

Yes, those tubular aluminum bolt-down units are basically just vitreous ceramic wirewounds cemented into a heat sink case. They are good at getting the heat out without going to insane temperatures (assuming adequate heat sinking to whatever they are bolted to) but have only about the same peak power capability of an air-cooled wirewound resistor.

Jon

So now you know the Ohms/square. ...Jim Thompson

It's very likely laser trimmed.

Should be visible. And easily calculated if you can use one of your "crutches" ;-) ...Jim Thompson

It's easy to calculate ohms/square, given a visible (maybe L-shaped, maybe multiple cut)laser trim on a rectangular ohmic patch?

Tell us how.

You forget I used to run the Dickson Electronics hybrid facility (NW corner of Thomas & Pima... I think it's Siemens now-a-days) and trimmed thick film every day. ...Jim Thompson

Do an easy case: 1 ohm per square, 1 square, contacts on two sides, 1 ohm untrimmed, single narrow cut sideways, starting in the middle of one non-contact side.

contact ============================ | | | | | | | cut | |------- | | | | | | | | | ============================ contact

Post the equation for ohms as a function of cut length.

Doesn't take any math (or equations) to get the _sheet_resistivity_ (which was the original statement, NOT Ohms per cut length), it just takes intuitive thought >:-}

As you emphasize, "Math and simulation are both crutches".

As soon as you admit you don't know how to attack the problem, I'll tell a trivial way to get an answer. ...Jim Thompson

You said the laser cut math was "easily calculated". You said you did trims every day. So do the math and post it.

What's your middle name, "Subterfuge"?

I said, "So now you know the Ohms/square."

In...

Date: Wed, 19 Mar 2014 14:28:33 -0700 Message-ID:

Stuff it up your nose, you can't even begin to present a solution.

There's a trivial way... shown _immediately_ upon your statement of incapability >:-} ...Jim Thompson

It's thick film, so I'm not sure (haven't done it for 41 years... don't know how well the technology has progressed in that much time) that 5% is doable with not only the paste variation, but the screen motion control. ...Jim Thompson

Put up or shut up.

So you can't even think of a way ?>:-}

Those of you who are curious, E-mail me... it's trivial, but wa-a-a-ay out of Larkin's capability >:-} ...Jim Thompson

Sad old fool. That's your standard ploy when you can't put up: go "private."

Somebody should call you on that.

the plastic from one of these

looks like just a big glob.

Not at 5% it is not.

?-)

You're the "sad old fool". "Sad old fool" isn't a physical age, it's a mental age, and Larkin, you're the "sad old fool" mentally.

There's a trivial way to derive the information we are seeking, but you're too dense, AND TOO HATEFUL, to find it.

Go away, mental midget, you're tiresome... everyone with half a brain... even those with a full brain, but half of it tied behind their back, will ignore Larkin. ...Jim Thompson