igorlab
Newbie
For one of my DIY projects, I need a circuit for pH reading. I have seen a lot of different schemas but some of them are unstable, another stable but oversensitive to electromagnetic interference. And when I've found, seemed, excellent schema and use it in few devices one problem has emerged. If disconnects pH electrode from PCB, without disconnecting electrical power supply - all amplifiers (LMC6042) and bipolar power source (A0505S-1W) overheats and make "pshh" with gray smoke in few seconds... maybe someone could give some advice - how this scheme could be modified to prevent component's damaging on disconnecting pH electrode?
p.s. The signal from a pH probe has a typical resistance between 10 MΩ and 1000 MΩ. Because of this high value, it is very important that the amplifier input currents be as small as possible. So pH-measuring supposes the use of a device with great input impedance, so adding of resistor between input cascade and ground is not variant, because it will damage the pH-probe.
I cant add a link to the project on easyeda, due to the forum restrictions, but add the img of the scheme.
Thanks in advance!
p.s. The signal from a pH probe has a typical resistance between 10 MΩ and 1000 MΩ. Because of this high value, it is very important that the amplifier input currents be as small as possible. So pH-measuring supposes the use of a device with great input impedance, so adding of resistor between input cascade and ground is not variant, because it will damage the pH-probe.
I cant add a link to the project on easyeda, due to the forum restrictions, but add the img of the scheme.
Thanks in advance!