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PaxInstruments / t100-electronics

A single thermocouple to USB adapter.
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Grounding the itothermal plane #46

Closed charlespax closed 9 years ago

charlespax commented 9 years ago

There has been a bit of research into how we should ground the isothermal plane on the T400. This has implications for the T100 also. It looks like we shouldn't be using an inductor, but a "zero ohm resistor." See https://github.com/PaxInstruments/t400-electronics/issues/59 and https://github.com/PaxInstruments/t400-electronics/issues/123

kehribar commented 9 years ago

Done. https://github.com/PaxInstruments/t100-electronics/commit/83a0ee97f4810c676c9682021250f756ca738d86

charlespax commented 9 years ago

@kehribar Should this be an inductor or just a trace? On the T400 we're using a trace.

@samchoy88 what's your opinion?

screen shot 2015-03-22 at 18 30 07

kehribar commented 9 years ago

It is just there to filter some AC noise of the USB supply. I think it should stay as an inductor. Also it isolates the MCU supply and analog supply as much as it can. You can find similar approach in most ADC datasheets.

You can try to desolder/short one and see the effect in terms of stability. It sure helps but maybe it is not that visible in the end due to other noise sources and etc.

Sent from mobile. On Mar 22, 2015 12:31 PM, "Charles Edward Pax" notifications@github.com wrote:

@kehribar https://github.com/kehribar Should this be an inductor or just a trace? On the T400 we're using a trace.

@samchoy88 https://github.com/samchoy88 what's your opinion?

[image: screen shot 2015-03-22 at 18 30 07] https://cloud.githubusercontent.com/assets/281642/6768976/80c2125a-d0c1-11e4-8daf-096d3bf841ef.png

— Reply to this email directly or view it on GitHub https://github.com/PaxInstruments/t100-electronics/issues/46#issuecomment-84583859 .

charlespax commented 9 years ago

Do you think we should do this on the T400 as well?

@samchoy88 thoughts?

charlespax commented 9 years ago

What should be the value of that inductor? It doesn't have a value in the Eagle schematic.

charlespax commented 9 years ago

@samchoy88 what do you think?

charlespax commented 9 years ago

For the next revision let's make a decision on the best solution.

charlespax commented 9 years ago

Please change this to a 0 Ohm resistor. I'm going to produce a batch, so I want the BoM to be correct for the factory.

charlespax commented 9 years ago

@kehribar this can be closed, right?

commit 1bf0f2758d1781c4f25094f72275e58422c0bae4
Author: kehribar <ihsan@kehribar.me>
Date:   Tue Aug 25 20:27:17 2015 +0300

    New library added. Inductor changed to resistor. Logo placement.