Normally a voltage drop would mean too much current but 220k and 150k is plenty of resistance.Double-check the resistors with a multimeter to make sure they really are that value (I know you're sure they are, but that's the symptoms...)
Good morning Divinitus. First a question. Are there other items, circuits, instruments, etc. in your project that depend on the source (Vin) remaining stable and constant.
From what you have described so far, voltage isn't the issue. You are wanting to measure *time*, the measure of which can be mathematically massaged to give you the viscosity measure you are looking for. Is my understanding correct?
If so, you may want to investigate using OpAmps for the so called sensors rather than a voltage divider. This would transition you out of the *analog* world and take you into the *digital* world. Much easier to measure time.
It sounds like the impedance of the Vin is very very high if it is being dragged down by a load of 370K.You have connected the grounds together haven't you?
What is the source of "Vin"?
It sounds like the impedance of the Vin is very very high if it is being dragged down by a load of 370K.
Quote from: James C4S on Mar 28, 2013, 05:37 pmWhat is the source of "Vin"?Basically the connects to the machine with a 4 pin connector. All voltages are DC. 24v for the stand to operate on, 1 pin for the upper optic voltage, 1 pin for the lower optic voltage (both a max of 12v) and a ground. The stand itself operates on 24v from a power supply that is also powering other components. The supply isn't the issue as it was well oversized, it's the circuitry inside the stand and the voltage divider.
The supply isn't the issue as it was well oversized,
Any possible alternative to a voltage divider....
Quote from: Divinitous on Mar 28, 2013, 05:16 pmAny possible alternative to a voltage divider....In theory: 10 times more resistance in your divider should mean 10 times less voltage drop (more or less).You could try putting bigger resistors in there, eg. in the megaohm range. The Arduino ADC input has 100 megaohm resistance so there's still some margin to work with.