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196  Forum 2005-2010 (read only) / Interfacing / Re: PT100 RTD interface on: July 16, 2010, 06:52:25 am
MCP609 has +vcc and gnd only. Am I wrong?
197  Forum 2005-2010 (read only) / Interfacing / Re: PT100 RTD interface on: July 16, 2010, 05:41:09 am
Quote
Well you know enough to spot the gain of the inverting amplifier was wrong.

Am I right?  :smiley

Quote
Note that Fig 5 is not a full schematic, you will need a split power supply as well as some decoupling and a decent layout. That is don't expect it to work well on solder less bread board.

split power supply:
I think you mean " a good Vref and GND". Can I use a 5v precision voltage reference for this circuit and for Arduino Aref?
198  Forum 2005-2010 (read only) / Interfacing / PT100 RTD interface on: July 16, 2010, 04:50:33 am
Hello.

I'm reading this note:

ww1.microchip.com/downloads/en/AppNotes/00687c.pdf
(page 4, figure 5)

and I've got some questions:

If I use a 5V Vref.... will i get 0-5v measure? will Irref be 1mA again?

How can I get aprox 0 volts at -50ºC and aprox Vref  at 350ºC? How can i tune the circuit to use all the ADC's range?

Thank you very much

PD:
Page 5, paragraph 1  -- R10 and R11 set a gain of 7.47 V/V. --
I think that is a mistake. 20.0k / 3.09k = 6.47
I'm not sure because i don't now anything about opamps

PD2:
I think that the solutions of my questions is near the filter and gain stage. Changing gain and adding offset, but I don't now how.

Thanks again.
199  Forum 2005-2010 (read only) / Interfacing / Re: Laser detection security on: July 13, 2010, 05:04:46 am
That project is in my list and i will use this one.

http://www.dealextreme.com/details.dx/sku.13378

I don't know if this laser will work or not
200  Forum 2005-2010 (read only) / Interfacing / how to use a rs422 encoder? on: July 13, 2010, 05:45:26 am
Hello.

I need to use this encoder:

www.connectric.com/Limes.pdf

and I've got some questions:

push-pull or line driver rs422?

what is the easiest way to link it to arduino?

some friend told me to use a transceiver but my electronic knowledge isn't enough to do it. can anybody tell me how to do it?

thanks.

my previous test was done with a computer mouse and interruptions but I think that this time will be more difficult.

thanks again.
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