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Topic: Voltage divider problem (Read 6 times) previous topic - next topic

Boopidoo

Yes, maybe. Do you have some ideas on such chips that I could use with the Arduino?

dhenry

Put a small capacitor on the analog input pin. Anything from 0.1n to 1000n will work.

The issue is that your input resistance is too high.


retrolefty


Yes, maybe. Do you have some ideas on such chips that I could use with the Arduino?


Here are two nice ones that adafruit sells:

12 bit ADC https://www.adafruit.com/products/1083

16 bit ADC https://www.adafruit.com/products/1085

I've got a ADS1115 module from an e-bay firm and was quite impressed with it's features and capabilities.

Lefty

oric_dan

What are the resistor tolerances on those adafruit devices?

Where they say 12 or 16-bit "precision", they actually mean resolution, and not accuracy.
You might be able to discriminate 1 part in 4096 or 65536, but the absolute value may
still be off by 5%, or 204  parts in 4096, or 3276 parts in 65536.

retrolefty


What are the resistor tolerances on those adafruit devices?

Where they say 12 or 16-bit "precision", they actually mean resolution, and not accuracy.
You might be able to discriminate 1 part in 4096 or 65536, but the absolute value may
still be off by 5%, or 204  parts in 4096, or 3276 parts in 65536.



The total word size (bits) determine the steps of resolution possible, the accuracy depends on the reference voltage used and of course the quality of the internal design of the chip. Both those models have an internal voltage reference as well as programmable gain settings, 4 single ended input channels or 2 differential input channels. The datasheet shows all the possible error tolerances and are impressive if you study ADC chips in the past. It's not a cheap chip but certainly a very powerful feature filled chip. Study the datasheet at your leisure.
http://www.ti.com/lit/ds/symlink/ads1115.pdf

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