Consider a "pre-amplified" pH sensor such as
https://www.omega.com/pptst/PHE9...
There is only a single BNC connection. Does the RTD temperature compensation as well as pre-amplification to turn high-impedance to low-impedance signal really work without a battery or other power source?
IIRC those usually have a self contained battery (button cell) for power.
Jim
Does that BNC connection require DC bias like some microphones? Omega spec sheet says NOTHING about battery; no hint from the controller spec sheet.
YSI talks about 1 to 2 year battery life. https://www.ysi.com/File%20Libra...
Jim
Does that BNC connection require DC bias like some microphones?
Good thinking -- hadn't thought of that...
But I don't think that is the power source, as we just connected to the BNC, used some acid/base fluids, and got some hundreds of millivolts.
Intersting, as the spec sheet is totally silent about battery.
Jim
Intersting, as the spec sheet is totally silent about battery.
Indeed, thus our confusion. The probe was pulled out of a box from Projects Past. Is a pH probe like a resistor such that they are all alike and the datasheet doesn't give any gory details?
... such that they are all alike ...
Follow-on related question: The datasheeets for the pre-amplified sensors don't give a value of how many mV are a pH "count". All the same -- "standard"?
All the same -- "standard"?
Maybe, don't know for sure.
IIRC, a generic pH probe, (probe and front end driver), (dual probe, or whatever it is actually called, that also contains its own internal reference cell), outputs 0 V at pH 7, and +/- 60 mV / pH unit.
I don't recall if increasing pH gives increasing voltage, or vice versa.
That "standard" probe could then get plugged into any of several different display (analog dial or digital) and / or PC interfaces.
If the probe is old it won't be of much use.
pH probes have a life span, and are suppose to be kept wet at a neutral pH when not in use.
They have a reference electrode with a chemical in it, and the reference chemical and the glass membrane all age.
JC
edit: typo
I don't recall if increasing pH gives increasing voltage, or vice versa.
https://www.atlas-scientific.com/_files/_datasheets/_oem/pH_oem_datasheet.pdf
(page 23)
Sensor Data
(uint32_t)
via
Atlas Scientific
pH OEM Circuit
https://www.atlas-scientific.com/product_pages/oem/oem_ph.html
(resolution is 1 milli-pH, 3.3..5.5V, 3..5mA, -40..+125C)
pH probes have a life span, ...
... and are suppose to be kept wet at a neutral pH when not in use.
Atlas Scientific
pH Reconditioning Kit
https://www.atlas-scientific.com/product_pages/chemicals/ph_recon.html
Atlas Scientific
pH
Edits: PIC18, typo
