hiii guys

i really need a help in my FYP , and its about non contact current sensor which is " Rrogowski Coil "

just to make it short
i have already design the coil and also the amplifier
the coil already work for high frequency ( 1 M ) and the result is 24mV, but my project is about low frequency between ( 1 f - 1k f )

so, i design the amplifier

which is non-invierter and my ( Rf = 100 K ohms , Ri = 1 K ohms )
so, my Gain is ( G = 100 )

when i pass 1M frequency through the coil and i connect the coil to my op-amp


but i dont get any result


could any 1 help me on that ?????????
why there is no result even the Gain is 100

 

Hello,

Can you post the circuit?
What opamp / amplifier do you use?

Greetings,
Bertus

 

im using op amp ( LT1014 )
and my circuit like that ---- > http://www.ecircuitcenter.com/Circuits/opnon/opnon.htm

non-invierting one

 

did you get it ????

 

What values did you use for R1 and R2?
If R1=101 Ohms and R2 = 10k Ohms, you will get a gain of approximately 100.

Post the design details of your Rogowski coil.

 

for R1 = 1k , and R2 = 100k
so, the Gain will be 100 .
and the design look like this
http://forum.allaboutcircuits.com/showthread.php?t=29886

 

This may help you, particularly the references therein:
http://forum.allaboutcircuits.com/showthread.php?t=14911

John

 

Thanx bro
i will try to do it tomorrow and see how its gonna work

 

The LT1014 has Gain-bandwidth product equal to 1 MHz. You use 1 MHz and have a gain equal to 100. That do not match very good
http://en.wikipedia.org/wiki/Gain-bandwidth_product

 

so, what i have to do ????
i have to increase it or decrease the gain ????

 

Hello,

You will need an opamp with a higher gain product ( > 100 MHz ).
I have attached a list of high speed opamps (remove the .txt and load it into excell).

Greetings,
Bertus

 

Yes you must a faster OPAMP. Why did you select the LT1014 in the first place? Also perhaps split up the gain stage. Instead of 1 stage with gain equal to 100 try two stages with gain equal to 10.

 

the coil already work for high frequency ( 1 M ) and the result is 24mV, but my project is about low frequency between ( 1 f - 1k f )

Did you read the article by Cappels here: http://www.cappels.org/dproj/aciprobe/ACCurrentProbe.html

He describes what you need to do to get low frequencies.

What do your calculations (see Cappels) show? Can you describe your coil to us in more detail? What actual frequencies have you tried?

John