I am trying to set up an Uno to monitor AC (120V range)and DC voltage (12V). I was told to use an optoisolator for the AC. Should I use one also for the DC?
Second question. I see a lot about the IL300, but the local electronic shop doesn't carry it. Are there others that would be comparable?
Third question. I usually see the IL300 used with op amps and found specifically the op-07. Is there a version of this or a comparable one that has 2 or 4 amps in a single chip?
Questions for you:
If a local store doesn't carry what you need try online. In my experience local stores only carry general items like resistors, pots, and some transistors.
Google this:
sensing detect ac voltage using microcontroller
I google that and found a couple of articles that explain how to detect AC voltage
Depending on the circuit, the op-amp could be amplifier the voltage that IL300 supplies to it.
Depending of what the current of what you are trying to sense is will determine how you are going to step down and detect the voltage.
racksmey:
Questions for you:
- Have looked up what an optoisolator is?
- Have you Google anything on detecting AC voltage or DC votage
- What current will be supplied?
If a local store doesn't carry what you need try online. In my experience local stores only carry general items like resistors, pots, and some transistors.
Google this:
sensing detect ac voltage using microcontroller
I google that and found a couple of articles that explain how to detect AC voltageDepending on the circuit, the op-amp could be amplifier the voltage that IL300 supplies to it.
Depending of what the current of what you are trying to sense is will determine how you are going to step down and detect the voltage.
Yes I have looked up what and optoisolator is and I understand what it does and how.
Yes I have been reading a lot about AV and DC voltage dection
In both cases a max of 30 amps. It is for a camper to monitor and record historic values. I am pretty good on the AC and DC current. the DC voltage would be a simple voltage divider. I was planning on basically using a bridge rectifier to get DC from the AC and a voltage divider to get it down to a 5 volt range. A friend suggested an optoisolator to protect the Uno. This was in the context of 120V AC. My first question was should I use for DC?
Second questions was because I can get an IL300 online and have found some good information about setting it up, but my local store does not have this one, but has 60 or so. I think they are all the type with one source and one detector, rather than one source and two detectors of the IL300. I was just looking for options as comparing data sheets is VERY time consuming and although I do know a bit about electronics and such, much of the datasheet is over my head and I am not sure what specs are necessarily important in the comparison. worst case I will order online.
cjdelphi:
For the ac you current transformer, as for DC, a voltage divider.
You would use a current transformer - which provides excellent isolation - if you wished to monitor current at mains voltage. If you wish to monitor voltage, then you use an ordinary transformer to step the mains down to a scaled voltage, such as 12V, then rectify it and use a voltage divider to reduce it to what you want for the Arduino analog inputs of 0 to 5V. The transformer will provide adequate isolation - that is exactly what they are designed to do (or you would not be using them for any purpose).
I have a suspicion that the 12V DC will actually be what is powering the Arduino anyway, so isolation is not going to be relevant as the ground will be commoned. Just a voltage divider is appropriate. In each case, the voltage divider uses resistors greater than 2k to limit abnormal transients into the analog input, though a couple of diodes to each power rail would be desirable in addition.
Opto-couplers are not so good at coupling linear values unless designed specially for that purpose, so they are not in general appropriate for this application.
Paul__B:
Opto-couplers are not so good at coupling linear values unless designed specially for that purpose, so they are not in general appropriate for this application.
The OP was talking about an IL300 driving an OP07 - how much more linear
can you get????
MarkT:
The OP was talking about an IL300 driving an OP07 - how much more linear
can you get?
Oh well. 
@parrst, do not cross-post. Other thread removed.
Paul__B:
The transformer will provide adequate isolation - that is exactly what they are designed to do (or you would not be using them for any purpose).
An autotransformer would disagree with such a broad statement.
Jiggy-Ninja:
An autotransformer would disagree with such a broad statement.
I bow to your proclivity for captiousness. 
Paul__B:
The transformer will provide adequate isolation - that is exactly what they are designed to do
That's a benefit but I'm not sure it was the design goal.
Paul__B:
(or you would not be using them for any purpose).
Not even for transforming voltages?
fungus:
That's a benefit but I'm not sure it was the design goal.
It certainly is nowadays with the profusion of "Plug pack" supplies with two pins and the requirement for "double insulation".
Note the present concern with the completely unusable Chinese "clone" imports of switchmode phone chargers.
fungus:
Not even for transforming voltages?
Not if they fail to keep the primary voltage separate from the secondary.
