Generic pressure sensors -SOLVED

[zboblamont]

Didn't find exactly what I was looking for in a forum search...

Bought two of these (Chinese?) pressure transducers and 1/2" adapters with the intent of monitoring pressure (initially at 2 points) in the pumped water supply which has various headlosses in the line.
These are listed as 5v supply, 0.5-4.5 output for 0-0.5MPa, 20mA consumption, beyond that only claims the response is "perfectly" linear.

The Node is 3.3v, 5v is available on-board from an external PSU, but the voltage output will have to be scaled down to suit the ADC pin, even more so if aiming for Vref 1.1.
Normally a high value resistance ladder would suffice, but concerned over effect on response (presumably a variable resistance device), checked output resistance to ground, at atmospheric ca 6.7 Mohm, purportedly corresponding to 0.5v.

It occurred to me that if it IS a variable resistance it should also function the same at 3v, so any here able to offer any insights, experience, or tips ?

[Yveaux]

@zboblamont can't you just try it? Nothing will break when powered below 5v, but you would have to apply the pressure somehow

[zboblamont]

@Yveaux Yes, but was hoping someone had already gone through similar experiments, and could advise what did/didn't work ;)
Your post prompted a reminder there is a 1/2" valved drain cock for the water meter/PRV in the bathroom... This would simplify testing without having to make plumbing alterations for the final locations :)

[Sasquatch]

It is most likely OP amp output you are seeing,
connect 5v, resistors as needed and multimeter to resistor output, check if works satisfactory, simple....

[zboblamont]

As a postscript to my own question should someone be looking at similar later, in practice the sensors were found to work perfectly well at 3v3.
Described as 5v working, 0.5-4.5v signal range, the effect is pro-rata at 3v3 in terms of voltage but the ADC output is identical for VCC scaling - viz, ZERO pressure is 10% of 1024 the range is 80%