This is a great product and I highly recommend it to anyone. It measures current from AC or DC without any loss in load voltage. However there is a minor inherit problem. Because the output is Ratio-metric, which means with no load the out is 1/2 of Vcc. It also means if Vcc changes the output will also change that could cause inaccurate readings.

To fixed this simply add a very stable 5V voltage reference thats capable of 20ma. I use these everywhere in my solar panel monitoring project

Does sparkfun actually read these? Last post was myself 7 months ago and nothing has come of it.

Is there an actual wiring diagram for this product? How do you connect the terminal wires from which you are trying to measure a current? Do you just thread the cables through the 2 holes, or do you connect them with "X" size screw? Or do you solder a copper wire to the sensor holes? Do you solder it to one of the 4 little solder points, or anywhere to the hole? The tutorials and examples are garbage compared to what I am used to with sparkfun.

FYI For non-power circuits this is likely not enough sensitivity. On the scale: 185mV / 1A, this is equivalent to 38 A/D counts per amp for 10 bit (1024 count) resolution (Arduino). That is equivalent to 26mA per A/D count resolution, as the A/D works at 4.9 mV / count. Could you make a more sensitive version?

If you're using this to monitor DC motor current, watch out for the motor magnets. When mounted a couple inches from our PM DC motor we got a huge (~0.5 amp) offset in the ACS712 output. So, back to the sense resistor for us. Aside from that the ACS712 seemed good.

Is there any chance we could get this board with the 20 or 30 amp IC?

@SparkFun Some suggestions for next time you order more of these for stock. I love this chip, but the PCB design renders this BOB nearly impossible to use.

1. Pull the ground plane fill away from the screw holes. If I tighten a nut down on these, it grounds out on the fill copper because it's too close to the holes. Don't even fill on that side of the chip; just leave the PCB bare.
2. Use smaller holes. It's only measuring up to 5A - we don't need #6 screws for that. Holes that accommodate a 3.5mm screw terminal would be optimum because we could solder in wires or a screw terminal.
3. Add a couple holes for a .1 in header, like you did on the low-current version of the board. Except make sure they line up so it can go into a breadboard.

Is there any chance we could get 20 of "ACS712" in one board?

I vote for the 20 amp version as well. I would buy a few of them right now.

I am considering using this breakout board with the ASC725-20AB, which can handle upto 20A, instead of the ACS712, which handles 5A. The new chip that I would replace would be connected to a wall outlet (max 15A b/c of the circuit breaker).

Do you think the "survival of the device up to 5 times overcurrent conditions" would let it be ok if I draw ~ 15A on this breakout replacing just the chip?

BEWARE!! this breakout do not provide isolation to measure AC mains. The board layout do not have the required creepage (distances in the pcb surface) to measure voltages far from the microcontroller ground. A gap of 2mm under the IC and no ground plane in the bottom layer is needed to take advantage of the isolation offered by the IC manufacturer. " 2.1 kVRMS isolation voltage from pins 1-4 to pins 5-8" .

Hi, I want to measure 5A output of a 220V 150/5A current transformer via this module. How do I do this?

I need to monitor the amperage of a 460v 3phs pump. The load will be 2-3 amps, and I want to use one sensor on each of the legs. Will this sensor handle that voltage?

In case this saves someone some time (since I just worked this out the hard way)... you can't use a current sensor with a stepper motor. Stepper motors run at full current all the time (so they can lock their position) so you can't detect (for example) an increase in current draw with an increase in load for current-control of the motor.

What formula is everyone using to convert Vout to current?

Going by the graph I found in the datasheet I used the following:

Current = [Vout - (Vcc/2)] * 5

At 0.5A, I get more or less accurate readings but wild swings at 0.01. People below me in the commends have said they go 6mA accuracy and I'm wondering if I'm calculating wrong.

Yusif Nurizade

When I measure AC current Vout is AC voltage or DC Voltage? Thanks

What type of capacitors are those on the wiring example? Where can I find them?

Is it possible to measure slightly more current than 5A with this? Say 7A or 8A?

Can i measure 220V AC current with this one or any acs7xx sensors?(acs714)

the 1nf cap should be included.

If we are measuring AC current, does it matter which terminal we connect the hot and neutral to?

I have a line that sometimes carries 230V AC and other times ~400DC when it is rectified. I could not identify from the datasheet if AC and DC have different properties for this sensor, if voltage is much of an issue or if it is ONLY the current it senses...

I will probably swap out the op-amp for a peak detector amplifier, I just need a Current/No Current detector that does not need re-calibrating with every current change . Can anyone advise me!!

When measuring AC current, does it simply give a sine wave output voltage centered on Vcc/2? I didn't see anything specific in the datasheet about AC input/output, just that the output is above Vcc/2 for positive current and below Vcc/2 for negative current. So that's why I'm thinking that it just gives me the corresponding sine wave output (again, centered on Vcc/2). If so, has anyone used it with a microcontroller to measure AC current? And if so, how did you rectify the output into a suitable DC voltage for the ADC? I'm guessing the simplest way (which isn't so simple) is to run the output through an op-amp to stiffen its output impedance (and besides that, I need to amplify the output anyway because I'm measuring fairly low AC current, less than 250mA) with Vcc/2 as one input thereby centering the op-amp's output signal at ground (the datasheet shows an example of that; also, without split power supply rails, an AC signal into an op-amp would just give me every other "hump" of a half wave output, like one side of a center-tap xformer), possibly cap it to reduce the ripple, and then run that final output into the ADC. The last thing I want to do is bring in split power supply rails just for getting a better rectified AC output. What a mess...

Has anyone does this? I feel the coming pain of lots of testing and screwing around to get this right, so I'm hoping someone's already done this who's willing to help a brother out :)

Thanks in advance for any ideas at all! :D

alright, the example code in the Wiring Example is meaningless. I've tested my code with both ACS712-05B and ACS712-20A versions. Accuracy is within =- 3mA

code: https://forum.sparkfun.com/viewtopic.php?f=6&t=33605&e=0

I just tried using the ACS712 board but for some reason I only get 0.60v of response from the Vout even if i don't put any current source, which should give me 2.56v if the Vcc is 5v. Could it be that it got burnt when i was solding it? Or is there another posibility?

what kind of header can you use for the big holes?

Just a quick warning to not use this to sense your main Utility Line. Most of them in the US have a 200A breaker, which means that you could see as much as 200A in the line, which from the description above sounds like it would burn out the sensor.

That said, most house circuits have 20A breakers, which shouldn't burn out this part, but it might not give you the data you want.

Hi All,

Is it possible to use this sensor to measure the input voltage being supplied to the controller to which this sensor is attached? Or is this only used to measure voltage/current on everythign but the power source to allow the sensor to operate?

Thanks

Noob question here: What terminals should I add to the current pads to connect 14AWG wire?

i would suggest uploading a new photo of the red PCB

30A demo board
There is also a 20A demo board.

hows about getting a version of the ACS714 like Pololu?? A +/-30amp version is a bit more suitable for robotics. I have used them and they work very well, would probably fit on this board.

Here's a link to the Allegro dev kit for 20A:
http://www.allegromicro.com/en/Products/Part_Numbers/0712/ACS712_Demo_Board.pdf
note that's 4oz copper on top/bot with via stitching... see page 7 of the above link
... most quick turn PCB's houses don't do that heavy a copper... and if they did it would be $$$
Link to the store $20.00:
http://prostores2.carrierzone.com/servlet/AllegroMicroSystems/Detail?no=386

Not sure if its in stock tho...

WAM
http://home.comcast.net/~ajawamnet/wc/wamcover.htm

Don't you think this is a bit overpriced?

Could we get the cross sectional area, conductor width, and #oz. copper for the current traces? I'd like to compare them to the IPC Temperature Charts to see if your breakout board (with the ACS712-5A already supplied) can handle the 30A version.
Or, if it's already been proven to work superbly under that condition (tested at 30Amax), I could just take Sparkfun's word for it. Thanks!

Suggestions for the next revision:
Mark the 'positive' current direction on the board mask, for the two big holes (with an arrow ideally, or + and -).
Also, standard size holes for the current connectors would be nice, to make it easier to connect headers. Perhaps in addition to the big holes?

I'd like to solder some standard male headers to the current pads, in order to be able to plug the board into a breadboard for prototyping.
Could anyone advise as to if that would work (filling the remaining space with solder), or give some tips?

Is there a description of how to calibrate these things online anywhere?

Anyone know if this is suitable for the mains? say 3A max @ 240v AC (UK). I had a quick skim through the datasheet, and didn't seem to find anything :/