Is my eTape faulty? Moderators: adafruit_support_bill, adafruit

[jwinterton]

Hi - I recently installed two 8" eTape sensors from Milone to measure nutrient levels in a hydroponics project. I noticed while calibrating that one is significantly out of spec.

It should be 1500Ω empty, 300Ω full, ± 10%. One sits nicely in this range but the other has an empty resistance of 1059Ω which is well outside the spec and overall its sensitivity seems poor and non-linear compared to the other. I have inspected it and can't see any obvious physical damage.

I really need it to be super accurate - I am hoping to replace an ultrasonic solution with an accuracy of +/- 2mm, so it needs to improve on that (and should from the spec).

Any thoughts appreciated,

Thanks.

[adafruit_support_mike]

Just to check, what resistance do you see across the reference pins 1 and 4?

[jwinterton]

Hello Mike,
The reference resistance is 1388 ohms.
Regards,
John

[adafruit_support_mike]

Thank you.

That value is within spec, and is farther from the measured sensor value than from the nominal value. That supports the idea that something is off in the sensor.

Send a note containing a link to this page and your order number to support@adafruit.com. The folks there will get you a replacement.

[jwinterton]

Cheers Mike - thanks for confirming.