Timeline for Help on understanding how a strange RTD reading circuit works
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 20, 2018 at 11:42 | comment | added | Andy aka | @hadez you did good!! | |
| Apr 20, 2018 at 10:20 | comment | added | hadez | @Andyaka EUREKA ... Your reference to CMR solved it for me. It was the bottom sense resistor that was baffling me (which as you stated is used for CMR). Thanks a lot. | |
| Apr 20, 2018 at 10:02 | vote | accept | hadez | ||
| Apr 20, 2018 at 9:15 | comment | added | Henry Crun | This supports both 2 wire and 4 wire RTD connections. In 2 wire, you also measure the temperature of the connecting wires. In 4 wire the connecting wires can be removed, if you know the current, and the current measurement R lets you work that out | |
| Apr 20, 2018 at 8:34 | comment | added | Andy aka | Well, an RTD needs a series resistor and given that the InAmp is differential using two resistors makes a lot of sense common-mode-rejection wise. Bear in mind that this site isn't a discussion site. You asked a question and I gave an answer. Sure, spin-offs are allowed up to a point so that's 33% of your quota used. Think about your next question carefully and don't make it too long-winded. You might surprise yourself and figure it out along the way. | |
| Apr 20, 2018 at 8:29 | comment | added | hadez | Why use the two resistors at the top and bottom of the circuit? I mean the two that are connected using analogue switches. | |
| Apr 20, 2018 at 8:25 | history | answered | Andy aka | CC BY-SA 3.0 |