# Data logger project

Joined Feb 21, 2019
17
Hi,

I am looking to use this data logger for a small project. I need to be able to read positive and negative voltages but it uses 0-5 V inputs.

Is there was a way for the analog inputs to be referenced to 2.5 V, allowing me to input a +/-1 V sensor? Anyone familiar with the board they are using for the data logger and know if it has such a feature?

The solution would look something like this:
sensor voltage = 0 V, data logger sees +2.5 V
sensor voltage = 1 V, data logger sees +3.5 V
sensor voltage = -1 V, data logger sees 1.5 V

Thanks
Dean

#### KeithWalker

Joined Jul 10, 2017
1,392
Hi,

I am looking to use this data logger for a small project. I need to be able to read positive and negative voltages but it uses 0-5 V inputs.

Is there was a way for the analog inputs to be referenced to 2.5 V, allowing me to input a +/-1 V sensor? Anyone familiar with the board they are using for the data logger and know if it has such a feature?

The solution would look something like this:
sensor voltage = 0 V, data logger sees +2.5 V
sensor voltage = 1 V, data logger sees +3.5 V
sensor voltage = -1 V, data logger sees 1.5 V

Thanks
Dean
Yes, you can do that. Insert a stable, low current 2.5V DC supply between the common reference of the signal and the common reference of the supply. Make sure that they are not both grounded. The accuracy of the results will depend on the stability of the supply.

Joined Feb 21, 2019
17
Yes, you can do that. Insert a stable, low current 2.5V DC supply between the common reference of the signal and the common reference of the supply. Make sure that they are not both grounded. The accuracy of the results will depend on the stability of the supply.
Thank you, would this be as simple as just putting a voltage regulator to the 5 V supply and connecting it’s output to the analog input along with the signal? So the input will see [(signal)+(2.5)] volts.

Or have I missed something?electronics is not my main occupation

Joined Feb 21, 2019
17
Thank you, would this be as simple as just putting a voltage regulator to the 5 V supply and connecting it’s output to the analog input along with the signal? So the input will see [(signal)+(2.5)] volts.

Or have I missed something?electronics is not my main occupation
I don’t think I am correct above. Maybe the voltage regulator is acting like a pull up resistor but on the common ground and pulling up to 2.5 V instead of high/low.

#### KeithWalker

Joined Jul 10, 2017
1,392
I don’t think I am correct above. Maybe the voltage regulator is acting like a pull up resistor but on the common ground and pulling up to 2.5 V instead of high/low.
Like this:

Joined Mar 10, 2018
4,057
A passive technique to offset a V, attached.

Regards, Dana.

#### Attachments

• 12 KB Views: 3
• 7.5 KB Views: 4