# How to use 3 pin current sensor

I have 3-pin current sensor honeywell csnf661

the pins are +V, -V, O/P or I+

I wanted to interface this on arduino and I followed the instruction at openenergymonitor.org

I am not sure if I am doing it right because the tutorial is using different current sensor

YHDC SCT-013-000 CT

Base on the datasheet, does it mean that I need to supply 12-15V?

After supplying voltage on current sensor, I'm still confuse where to connect them since there are only 2 lines (I highlighted them with red lines).

Do I need to connect the +V and -V, or -V and I+?

The sensor that you have chosen appears to be similar to the LEM series of closed-loop-servo Hall-Effect current sensors. These are absolutely awesome sensors and are extremely easy to use.

Do note that the sensor is intended to be used with a bipolar DC power supply of plus minus 12-15 Vdc. The output is a CURRENT which is directly proportional to the input current.

It looks as if this is a 1000:1 current sensor with a nominal input current range of up to 150 Amps. The output current is 1/1000 of the input current.

You can interface this with your Arduino by connecting the sensor output pin to a burden resistor that gives you your desired sensitivity. Do note that because the sensor will supply voltage above and below ground, the Arduino with pick up only positive current.

You can offset the output from the sensor if you capacitively-couple the output voltage from the burden resistor into the Arduino input, along with a 2:1 voltage divider from your Arduino supply rail to bias the analog input at the 1/2 Vdd point.

There are some specifications that you should define first, such as your expected min and max sensed current. With those values you can design your interface to the Arduino.

To use the current sensor, connect 12-15VDC to V+ and V-. The remaining pin is the sensed current output which should be connected to a resistor (with a resistance suited for your min/max values) and then possibly to a voltage divider (if needed). Then this output is connected to your Arduino ADC input to read the voltage, and then performs the computation to get your current value (I = V/R).