i want to read the current of a device and read the current to my computer
does anyone here knows how could I read the current of a simple device into my pC? i have been reading some analog to digital converters lately, but the required input is only the voltage, therefore, it only converts the voltage analog input to voltage digital output, which i can see in my PC. but i also want the readings of the current. is this possible? tnx!
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Tracy Allen
www.emesystems.com
You pass the wire through the center of the torroid.
This eliminates the need to directly attach wire to the circuit in question and having to use an extremely low resistance, high wattage resistor to get a measurement. It works by induction.
Having said that, it is quite a challenging DIY project. There are AC current devices that are sold that do this. I am not sure about DC.
If there is a AC?DC applicance, it may have a digital interface.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
The ferrite toroid is just a dounut shaped piece of ferrite that is usually used as a transformer's core because it responses well to transfering magnetic force.
The idea is to read the magnetic field associated with the current rather than read a voltage differential across a known resistor. You cut a slot to actually place the Hall effect sensor into a position where its ability is enhanced by the ferrite toroid and is able to provide stable readings.
There are two types of Hall-effect sensors. One is a flip/flop logic and no good for this applcation. It turns on when one pole is near and turns off when the other pole is near.·
The second type of Hall-effect measures intensity and you would used it somewhat similarly to a transistor. You would have to engineer it to operate in a linear region, you would have to calibrated to a known current to have useful information, and you may have to create several switched ranges [noparse][[/noparse]like a VOM] to get a full range of information.
Since the output is purely analog, you would have to use an Analogue to Digitial Converter or a digital VOM with computer interface to have the information arrive at your PC.
As I mentioned earlier, a bit challenging for a DIY project.
AS far as design parameters, you give me 0 to +10v, but that isn't current. One would need to know what range of amps too in order to estimate the magnetic field created.
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"If you want more fiber, eat the package.· Not enough?· Eat the manual."········
What is your expected current range?
I'm looking at the same thing. I want to measure DC current at 5V, and make some decisions when the current gets up to about 5.5A.
I think the solution lies close to an Analog - Digital Converter and a shunt resistor, but I'm so new to this don't take my word for it. You measure the voltage drop across the shunt somehow, send it to the ADC and somehow get it to the input pins. I don't know yet.
Have you figured it out? If so' I'd love a leg up.
Tom
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Engineering is the art of doing·something well with one dollar, which any bungler can do with two after a fashion.
http://www.uoguelph.ca/~antoon/gadgets/shunts/shunts.html
Jeff T.
The link that gave you will work and the way that you do this as follows
(1) Take a auto light bulb for a tail light and mesure the amp draw
(2) You need to know what your mil volt scale will be
(3) Take wire size that you are use and strip it··i would say about 4 inchs more or less·and put one lead of the meter·and then other lead and move it down the wire until you get the milvolts scale that you need for the amp scale that you want to use
I would say that to make it easy 1 amp = 100 millvolts and the a/d converter
this might not be right it was a while ago that i did this and this was for panel meter that i did it for
If you tell me the· mil volts scale and what amp, from milamp·to amp ·that you will used
and what wire size that you will use i will try it and let you what will work
There is a project that i will be working on latter next year that i will need to know this info my self
·
I have done this for home made power supplys that i wanted an amp meter and a voltage reading and the· acuracy· is perty good
But BE VERY CAREFULL WHEN YOU DO THIS NOT TO SHORT ANY THING OUT WITH THE BARE WIRE THAT YOU ARE USING
FOR YOUR TESTING
The· acuracy is fairly good if you take different thing to mearsure take a lamp that draws let say 2 amps then take a lamp
that draw 1 amp and one that draws 500 milamp and so on and adj your wire lenght for best· acuracy· in what range that
you need you check with meter that you tested the lenght wire
I hope this help you in what you want to
Sam
Post Edited (sam_sam_sam) : 12/11/2006 5:49:43 AM GMT