Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [ph]

In chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline.

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Considerations for PCB guard ring trace for PH probe

Long time lurker first time poster. I have questions regarding PCB guard rings in a pH meter circuit. I know that a typical combination pH electrode has really high output impedance so you want low leakage on the PCB as well as low input offset…
Andy
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Assistance with schematic notation "R@2V" for pH monitor

I've been building a circuit I found online for a pH monitor, while most of the circuit seems straight forward I get caught on the "R@2V" notation, a guess would be maybe resistance at 2 volts? I'm not completely sure and if so not certain how I…
Tim Kalinowski
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Ground loop impedance when measuring pH of salty/conductive liquids

I have a reservoir of conductive liquid (~2000 μS). Inside that liquid are two sensors: a pH sensor and a conductivity cell. The conductivity cell is a two-terminal device and submerged. When excitation voltage is not applied the sensor electrodes…
Rherma
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PH Probe Unstable Measurement

I've recently set up a small circuit for PH measurement using a BNC PH electrode. A picture of my circuit can be seen below: The linear reference REF1 alongside opamp U1A serve to generate a 2.5V buffer voltage so that the voltage generated by the…
Platytude
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Building a pH meter circuit - is it feasible?

Let's say I have a budget of $15-20 to build a pH meter. I will then read the analog values from a microcontroller or such, but I want to first focus on somehow getting a reliable pH value on a shoestring budget. First of all, is this even possible…
T.K.
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ESD protection for pH measurement electrode input

I want to puild a pH meter, which uses a normal glass electrode. Such an electrode behaves as a pH dependend voltage source (<+-500mV) with very high internal resistance (10MOhm - 1GOhm, depending on the electrode). As a consequence, the voltage…
Medo42
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pH sensor buffering, gain, and offset with one inverting opamp

I'm working on the above mentioned circuit. I'm a hobbyist with little electronics training so don't laugh if something terribly dumb comes out of my keyboard please. Anyway, a different question on stackexchange had a comment that opamps don't need…
user3758018
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pH sensor project: trouble with RF interference

I built this pH sensor project on a breadboard and I'm having a big problem. The output on the voltmeter is completely erratic, and I'm pretty sure it's due to RF interference. When I connect the probe (via BNC connector), moving the cable or my…
karl333
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Ground loop when measuring in process pH

I have been experiencing a very difficult to solve ground loop problem with my pH measuring system. My basic setup is a standard pH electrode running through an op-amp to an ADC which communicates through I2C to a Raspberry Pi. Calibration of the…
Chesrae
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How do I hijack a reading from the circuit of my digital meter

I have a tri - meter (ph, ppm, temp) that reads and displays readings on three LCD screens. I'm trying to hijack the measurement at some point in the circuit and read it in through on of the inputs on my Arduino. Can anyone tell me where I might…
user379468
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Creating a pH Sensor Simulator

I'm currently trying to create a pH sensor glass electrode simulator capable of generating a millivolt output that can be read by a pH sensor. I'm not trying to simulate the pH sensor output, rather the input to the electronics on the sensor that…
Patrick Voorhoeve
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EC and pH sensor in plc automation

I am working with automation using pH and EC sensors. Both are of 4-20mA communication standard. When at a time single sensor is placed in liquid(in 1000 litre tank) then everything works fine (correct value is given). But when both sensors are…
Jashanjot Kaur
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PH 4502 electrical interference EMI when in aquarium

I'm trying to get a regular ph reading in an aquarium. The sensor works well when the probe is in a small quantity of water(i.e. a glass) but has large variations in larger water quantities (i.e. aquarium). The circuit uses an ads1115 and a node…
gedorin
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Why does an ISFET need a reference electrode?

I'm trying to understand why an ISFET needs a reference electrode. I have looked up several answers online but still dont understand. I have drawn out the doping, a MOSFET and the ISFET: In my mind, a change in pH changed the H concentration…
Leo
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pH sensor voltage versus pH

I am currently in the process of making an ultra-low power pH captor and I'm running in a problem. The voltage I get from my pH probe does not fallow the Nernst equation (which states that the voltage should increase/decrease of 59 mV per pH unit).…
Nathaniel Brochu
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