Hello folks,

I am trying to automate the following circuitry (see attached doc.) using an Arduino, relay and a current sensor. The aim is to find the currents at each load (10kΩ, 1kΩ, 2000pF, and 20000pF). My Arduino connections are as follows:

• Relay COM terminals (K1, K2, K3, and K4) are connected to point P.
• NO relay terminals are connected to each load (10kΩ, 1kΩ, 2000pF, 20000pF).
• The other end of each load is grounded.
• A 5V power supply is connected to the relay VCC, and the relay ground is connected to the common GND pin.
• Relay IN1 to IN4 are connected to Arduino digital pins D2 to D5.

I used an Adafruit INA219 current sensor. The expected values are:

• No load: Less than 1.3 mA
• 10kΩ load: Less than 1.8 mA
• 1kΩ load: Less than 3.1 mA
• 2000pF load: Less than 3.1 mA
• 20000pF load: Less than 10.0 mA

I connected the current sensor like this:

• Vin+ to point P
• Vin- to the load side (one at time)
• SCL to SCL Arduino
• SDA to SDA Arduino
• VCC to 5V
• GND to GND

However, I am not getting the correct measurements. I don’t know where I went wrong. Any suggestions, like using a multimeter instead of the current sensor and taking readings with the Arduino, or any other advice, would be greatly appreciated!

Thanks in advance!

 

It might be that the resistance of the current sensor and the resistance of whatever else you are using to measure the current are affecting the current. A series resistance usually affects the current. So that could be the problem.
This analysis is based on an experience based guess, as we are not given the information needed for a reasonable evaluation. That could include actual data.