 # Current Sensor

Hi. I'm trying to build a device that measure the time a circuit is running. The circuit has a switch and i want to detect when the switch is on (the circuit is closed). I thought to do it by checking if there is current after the switch how can i do it?
Thanks

The type of sensor you need depends on the following:

• What' the current range, less than an amp or 10s of amps?
• AC or DC?
• Is the circuit voltage greater than 50v?

If you don't know then you need to take some measurements using a multimeter.

It has 24V and current between 100A-225A.
I only need to detect if there is current not how much is it

Yescas:
Hi. I'm trying to build a device that measure the time a circuit is running.
The circuit has a switch and i want to detect when the switch is on (the circuit is closed).

I thought to do it by checking if there is current after the switch how can i do it?

Why not simply detect if there is voltage (not current) after the switch.

Use a voltage divider (two resistors) to bring that 24volt down to 5volt (assuming 5volt Arduino).
10k (pin to ground) and 39k (pin to 24volt) would do.
Leo..

You could measure the Voltage drop across a heavy connecting cable which is already in circuit, or include a shunt and measure the drop across that.

Hi, im building a current sensor using INA219 and would like to know how would I go about coding when my arduino is off or on perform this action, Thank you

Azola:
Hi, im building a current sensor using INA219 and would like to know how would I go about coding when my arduino is off or on perform this action, Thank you

This likely would have gone better if you started your own new thread and you need to well define your objective. Everything you ask depends on exactly what you plan to input to the Arduino ADC (Analog In) pins. For example:

I am building or using a current sensor which converts or outputs 0 to 25 amps of DC current to a 0 to 5 volt analog signal. I plan to read this using an Arduino Uno and wish the serial monitor to display Amps, I also plan to use an LCD which is a 4 line 20 character display. Here is my code and can someone help me with this project. My code is as follows: (Include your code using code tags).