4-20mA Precision Source Ideas

Of course. Rules are the things I make up.

It isn't

I make up standards, too.

John

Turning off pixels Saves the Earth!

John

:)

Jamie

You needed to quote 103 lines just to post that pathetic horseshit?

Something you understand, naturally.

Jamie

Burr Brown, now TI, had several 4-20ma devices, the XTR family. One of them may fit your needs. Art

You needed to snip my good lines just to post your whining?

John

Well, then write a letter to your congressperson.

I'd better not show you how I draw mosfets or schottky diodes. You might have a stroke.

John

I still draw schematics on D-size blue-grid vellum, with a Berol F pencil. I draw handsome, bold, unmistakable connection dots. The Brat CADs them and does the PCB layout. I don't recall us ever getting a connection dot wrong.

The offset tee thing is often ugly.

John

...

Why do you seek one true way? Are you really not able to another's circuit intent even when they don't follow your particular idea of layout rules? I wonder sometimes whether you ever use a soldering iron, produce anything other than simulations?

Grant.

...

You already did that, and we had our collective strokes at the time, as far as myself -- you helped aid my continuing confusion as to which way the arrow goes with a MOSFET symbol ;) I gotta look near every time I draw one now! :o) Schottkys don't bother me.

Who cares, bottom line? One self and their very own set of production staff and customers. Besides, there was a great man who documented much of the Internet's early decades, Jon Postel. I suggest the naysayers on freedom of expression check Jon's famous quote. Because the Internet was built on that simple concept. More engineering fields could use it.

Trouble is, it requires reason, thinking, and care in what one does.

Grant.

Until they discontinue it.. they've dropped a bunch of those products.

Best regards, Spehro Pefhany

Sketches aren't intended to become PC boards... they just suggest ideas.

Here's an actual input I gave The Brat, on vellum:

ftp://jjlarkin.lmi.net/FilterBoard.jpg

I let her pick the actual pin assignments on this little board and on the big board it plugs onto.

ftp://jjlarkin.lmi.net/Filter1.jpg

ftp://jjlarkin.lmi.net/Filter2.jpg

After it's entered into PADS, I'll check it myself. Ditto the PCB after it's laid out. Before we release the Gerbers, we'll have a group design review, with pizza.

It's a mistake we just don't make. We rarely make connection or pin type errors, because we're careful. We make far more sophisticated errors, but most rev A boards can be sold... and we don't make prototypes.

I made a mistake on this little board, and had to make a fix on rev B. Turns out the chopamps have a DC offset that's a function of the capacitance at their input pins, so I was getting overall filter offsets in the 10 uV range or so. We can cal that out for factory-installed filters, but I want them to be field interchangable, so rev B added a really tiny offset trimpot.

John

Thanks, I had not seen these - but they look too expensive for this application.

JF follows me around and whines about any opinions that I have. It's kind of creepy.

John