08-19-2025, 04:34 AM
(This post was last modified: 08-19-2025, 04:37 AM by Onepointbrewing.)
Im having trouble with a pressure transmitter (4-20mA @24v).
It suffers from decay over a period of time. I asked chatGPT to help out and it says that its caused by “the repeated conversions act like a little pump that drags the node down, so the reported value “decays” over minutes/hours”
Ok so I get it (sort of) so I installed a 250ohm shunt resistor between the ADC IP (the op of the sensor) and GND. It also suggests installing a 0.1uF cap in the same spot (in parallel w the shunt resistor)
1: this stabilizes the measurement for approx 2-3hrs and then the decay resumes. Would a lower resistsor give me a more reliable time duration???
2: Not sure about the 0.1uF cap except for reducing line noise…
Is this correct and can someone point me to a picture somewhere in the internet that shows a cct diagram.
Thanks
i have isolated the code and its not to do with the code, its the electronics side.
So is the cct below a better way of fixing the issue????
It suffers from decay over a period of time. I asked chatGPT to help out and it says that its caused by “the repeated conversions act like a little pump that drags the node down, so the reported value “decays” over minutes/hours”
Ok so I get it (sort of) so I installed a 250ohm shunt resistor between the ADC IP (the op of the sensor) and GND. It also suggests installing a 0.1uF cap in the same spot (in parallel w the shunt resistor)
1: this stabilizes the measurement for approx 2-3hrs and then the decay resumes. Would a lower resistsor give me a more reliable time duration???
2: Not sure about the 0.1uF cap except for reducing line noise…
Is this correct and can someone point me to a picture somewhere in the internet that shows a cct diagram.
Thanks
i have isolated the code and its not to do with the code, its the electronics side.
So is the cct below a better way of fixing the issue????