Hello everyone,

I want to build a circuit that can signal an Arduino that an AC voltage is present in a cable or not. I am not interested in measuring the AC volt/current. Since I have no experience working with AC circuits, I would prefer a contactless solution.

I am clueless on how to proceed

 

What is the AC voltage?
120/240V?
50/60 Hz?

 

Use an AC field probe

http://www.circuitdiagram.org/non-contact-ac-voltage-detector.html

 

What is the AC voltage?
120/240V?
50/60 Hz?

230V 50Hz

 

Here is the safe way of doing it:

Get an old 4Vdc to 5Vdc (no higher) cell-phone charger that looks like this:

Cut off the output plug, and wire it to a load resistor, like 470Ω or 1KΩ. Check the output voltage across the resistor with a DC Voltmeter. If 5Vdc or less, wire the 0V output end of the resistor to the Arduino Vss (Gnd), and wire the +5V output end to an Arduino Port pin.

 

see circuit in post #3, contactless detection

 

see circuit in post #3, contactless detection

Won't work if no current is flowing in the sensed circuit.

 

Do you need contact-less voltage detection even in the absence of current?
Max.

 

http://www.circuitdiagram.org/non-contact-ac-voltage-detector.html

 

Thank you for all the replies. Like I said, I have never worked with AC powered circuits before. Basically what I want to know is: is there AC power in the cable, yes or no.

 

Here is one from another site.

Max.

 

... I have never worked with AC powered circuits before....

Good reason to use the cell-phone charger...

 

What kind of cable are you working with?

Ken

 

It is a standard "household" cable that is rated at 20A. I think just to clarify further: I want to monitor several mains appliances/devices to see of they are still receiving AC power from the grid.

Something like: TV power ON; Fridge power ON; Fan power OFF; and so on. The idea is to determine whether there is a general power failure (blackout) or just one circuit breaker tripped.

 

A volt stick.

http://www.ebay.com/itm/201283987337?redirect=mobile

 

A volt stick.

http://www.ebay.com/itm/201283987337?redirect=mobile

This looks interesting. I'm sure I'll be able to open it up and hack to provide input to the Arduino. At that price point, it is probably cheaper than a DIY solution as well.

 

This looks interesting. I'm sure I'll be able to open it up and hack to provide input to the Arduino. At that price point, it is probably cheaper than a DIY solution as well.

In many cases these electricians neon type testers require that the unit be held by the operator for them to operate via earth leakage, the return path is a very minute current through the body.
Max.

 

I have at home a stud finder with wireing detector. it is for findi9ng studs in walls and live circuits in walls. it uses a coil like the previous diagram (numbedr 11) and works by induction. even a circuit drawing no current will show its there. ou might try a small ausio transformer, remove the Bridge from it and the open end of the E shaped core should pick up ac induction.

 

Hello everyone,

Again, thank you for all the replies. I also came across this: http://electronics.stackexchange.com/questions/94782/capacitive-ac-voltage-detection

I built the circuit on a breadboard, and it works very well. I have not actually connected it to an Arduino yet, just tested it with a DMM.