Timeline for RTD sensor circuit design
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 21, 2018 at 19:25 | comment | added | Spehro 'speff' Pefhany | @EmilyL. LOL. Looking forward to your follow-ups then. | |
| May 21, 2018 at 18:20 | comment | added | Emily L. | CHALLENGE ACCEPTED :P | |
| May 21, 2018 at 17:56 | comment | added | Spehro 'speff' Pefhany | NTC thermistors are great, especially for a narrow temperature range, because they are so sensitive it's hard to do it wrong. | |
| May 21, 2018 at 16:23 | vote | accept | Emily L. | ||
| May 21, 2018 at 16:23 | comment | added | Emily L. | Oh cool thing with the op-amps to create a current source and removing the wire resistance using a subtracting opamp (whatever you call that arrangement). Based on Henry's comment I've decided to o with a NTC thermistor instead, I think it'll suit my application better. I'll accept your answer nonetheless. | |
| May 20, 2018 at 23:44 | comment | added | Spehro 'speff' Pefhany | By wrapping an op-amp, I mean drive the gate of a single MOSFET with an op-amp, use a sense resistor in the source and feed it a suitable reference (eg. 0.25VDC, perhaps divided down from an accurate/stable 2.50V reference). If you look up current source/sink you will find this is a standard building block. | |
| May 20, 2018 at 23:40 | comment | added | Spehro 'speff' Pefhany | Have a look at this Microchip app note for a relatively simple approach (you may have to change some values for your situation). I'm not a big fan of their filtering (seems like a student approach, it would never pass industrial conditions) but if you slap some caps (eg. 10n) across the input terminals to ground it's probably okay for your relatively benign situation. | |
| May 20, 2018 at 23:34 | comment | added | Emily L. | Could you elaborate on wrapping the current sink in an opamp, I don't quite understand what you mean? The edges of the operating region of the opamp if far outside of the expected voltage output range. Should I filter ahead of both op amps? Or just the first? And thank you for your feedback. | |
| May 20, 2018 at 23:21 | history | edited | Spehro 'speff' Pefhany | CC BY-SA 4.0 |
added 347 characters in body
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| May 20, 2018 at 23:12 | history | answered | Spehro 'speff' Pefhany | CC BY-SA 4.0 |