First I'll layout the basics of what I'm trying to do.
I have a siemens s7 216 plc with an anlog input module that I want to read a signal from a PH probe, they can't be directly connected because the ph probe provides a high impedence signal that the plc cannot read. There needs to be a middle man, which would be the transmitter that provides either a -5v to +5v signal or 0v to 10v signal at 4-20ma.
I've found a few schematics that seem to look like they'd work for this setup, here they are. I'd like to have to ability to calibrate the probe when its put in a test solution of a ph 7. But thats not really what I'm concered with at this point. This is for a diy project I'm working on, its not for profit and I'm trying to save $250 by building my own, a circuit like this premade goes for roughly that much which I think is redicolous for the average person not business.
Here are the schematics I've found that look promising. I'd like as much input as possible. I deal with mainly electrical aspects of stuff, I'm an electrician by occupation so my electronics background is limited to I know what components are and what they do, but its hard for me to sit there and peice together a circuit by hand on my own.
Schematics
https://www.cyberreefguru.com/electronics/phmeter3.gif
https://www.cyberreefguru.com/electronics/phmeter2.gif[/url]
I have a siemens s7 216 plc with an anlog input module that I want to read a signal from a PH probe, they can't be directly connected because the ph probe provides a high impedence signal that the plc cannot read. There needs to be a middle man, which would be the transmitter that provides either a -5v to +5v signal or 0v to 10v signal at 4-20ma.
I've found a few schematics that seem to look like they'd work for this setup, here they are. I'd like to have to ability to calibrate the probe when its put in a test solution of a ph 7. But thats not really what I'm concered with at this point. This is for a diy project I'm working on, its not for profit and I'm trying to save $250 by building my own, a circuit like this premade goes for roughly that much which I think is redicolous for the average person not business.
Here are the schematics I've found that look promising. I'd like as much input as possible. I deal with mainly electrical aspects of stuff, I'm an electrician by occupation so my electronics background is limited to I know what components are and what they do, but its hard for me to sit there and peice together a circuit by hand on my own.
Schematics
https://www.cyberreefguru.com/electronics/phmeter3.gif
https://www.cyberreefguru.com/electronics/phmeter2.gif[/url]