Hi,
I would like to be able to measure a voltage that swings between +15V and -15V using the analog input on the K8055. I need to proportionately reduce the voltage so that it will be in the 0 to +5V range.
What is the best method of doing this? An idea for a circuit would be much appreciated.
Kind regards,
John Orme
Just add 68k resistor between the +5V of the K8055 card and the input A1. Connect your voltage (-15V…+15V) via a 200k or 220k resistor to A1.
The 101k is RV1 + R3 on the card.
Great! Thanks very much for this. Out of interest, how did you work out the values?
Many Thanks,
John O
Hope it works OK too.
First I estimated rough values for the two resistors.
Then I simulated it using the MicroCap 8 simulation software.
In the simulation the input was a ramp wave going from -15V to +15V.
The resistor values are selected so that the output ramps from 0V to +5V.
It was quite easy to find a combination of standard resistor values.
This kind of simple circuits (up to 50 components) can be simulated with the free evaluation version of the MicroCap.
microcapsoftware.com/index.shtm
Great! Brilliant! Thanks!