220V AC detection

Hello,

Any cheap and easy way to detect 220V AC?

I just want to log when an appliance is working or not.

Thanks,

Andreas

Any cheap and easy way to detect 220V AC?

Lick your finger and stick it in the socket. You'll have no doubt whether there is 220 present.

You didn't mention safe as a criteria ;)

One way might be to find a cheap 'wall wart' power module rated for 220ac input and DC output. Then you could use a simple 2 resistor voltage divider in the voltage rating is higher then 5vdc and wire that into either a digital input or even a analog input pin.

Something like this might work: http://www.allelectronics.com/make-a-store/item/PS-478/4.7-VDC-850MA-POWER-SUPPLY/1.html

Please be careful wiring around 220ac, it can be very unforgiving.

Lefty

check out:

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1235146158

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1253772264

-j

Here's a suggested circuit (note the changes for 220VAC at the bottom):

http://ruggedcircuits.com/html/circuit__26.html

-- The Rugged Motor Driver: two H-bridges, more power than an L298, fully protected

Here's a suggested circuit (note the changes for 220VAC at the bottom):

Before anyone rush off to implement the above reference, you may want to note that this will put in excess of 300V across the current limiting resistor and this is typically outside specifications for most common resistors.

Also you need to verify that your mains supply is of the star shaped type (has a hot and neutral wire). Many AC generators will not and some countries (I know of Albania and Norway) use a delta shaped mains net.

If you don't know how to handle the above issues properly in relation to your mains supply, you are better off with the proposed idea from retrolefty (using an isolation transformer) and sense on the low voltage side.

Before anyone rush off to implement the above reference, you may want to note that this will put in excess of 300V across the current limiting resistor and this is typically outside specifications for most common resistors.

Good point...most chip resistors are rated for 200V. Putting two resistors in series is a simple enough method to address this. I'll make a note of that.

Also you need to verify that your mains supply is of the star shaped type (has a hot and neutral wire). Many AC generators will not and some countries (I know of Albania and Norway) use a delta shaped mains net.

That's interesting...I did not know that. How does that affect the functionality of the circuit?

-- The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, light sensor, potentiometers, pushbuttons

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That's interesting...I did not know that. How does that affect the functionality of the circuit?

As it is now you're good for star shaped nets as reverse voltage would stay across the 1N4004 diode, but for a delta shaped net you will develop reverse voltage across the led when the two phases reverse polarity. Typical reverse breakdown voltage for a led is around 50V and I see nothing in the YTLP781 datasheet to suggest it is different.

So you would need to protect the TLP781 led from reverse breakdown. This could be a reverse diode in parallel with the led or you could choose an AC photo coupler with dual opposite led's.

I'm still not understanding. The two phases reverse polarity even now. Half the time the voltage input (top pin) goes up to +169V and the other half of the time it goes down to -169V relative to GNDA. That's when diode D1 prevents reverse breakdown in the LED.

I'm afraid I still don't understand how a delta connection would be any different from the point of view of voltage magnitude and polarity reversal. Looks like I'll have to go off and do some more reading....

-- The Quick Shield: breakout all 28 pins to quick-connect terminals

Cheap and easy: http://cgi.ebay.com/USB-AC-Power-Supply-Wall-Adapter-MP3-Charger-US-2P-Plug-/300422883221?pt=Other_MP3_Player_Accessories&hash=item45f2996795

:D

And wire the +5 to a digital input in arduino and gnd to gnd of course

Thank U all for the answers.

What If I ask U to detect 220V AC current?? Any easy solution (I don't want to put my finger in the plug).

Regards

Do you mean 'detect' or 'measure'?

Detect is more than enough

Linear hall effect sensor taped to the outside of the plastic insulated live wire. (not the whole lot - live, neatural and earth).

Easy.

Like this one?

http://cgi.ebay.com/10-x-A1302-RATIOMETRIC-LINEAR-HALL-EFFECT-SONSOR-/220666382054?pt=LH_DefaultDomain_0&hash=item3360bdc6e6

What current do you think it can detect?

thx

Well you didn't state that. It's not a well regarded way of doing it but just for sensing current (no idea on how much - depends on the hall effect sensor) it would work. For sensing 'an appliance' it might work.

You can buy specific sensors designed for sensing current, just search - 'current sensor' on your favourite parts website.

Mowcius

I think I'd be tempted by 4 or 5 discrete components and tape it up good to keep the high voltages at bay........ :)