Author Topic: current sensor  (Read 384 times)

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Offline m.jayid

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current sensor
« on: April 18, 2021, 01:26:25 pm »
Hi everybody.
CAn someone please explain me.
What is the relation between the input and output of this amplifier. (please see attachement)
And what is the purpose of the elements in the circuit. (capacitors , resistors ...)
This sensor is used at the output of an inverter.
Thank you so much.
Edit :
I am not very much familiar with electronic.
In fact I would like to know which type of amplifier is this and what is the relation between the input of the amplifier and its output.
What is the purpose of C77 .
What is the cutoff frequency of the filters used in the circuit.
Thank you  .
« Last Edit: April 18, 2021, 02:03:09 pm by m.jayid »
 

Offline t1d

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Re: current sensor
« Reply #1 on: April 18, 2021, 01:42:36 pm »
Your questions seems (to me) to be a bit vague, but here is the short answer... The blue coil senses the current of a wire that has been passed through the hole that is in its center. The op amp circuitry conditions the signal that was captured by the blue coil, so that the signal information can be used by the circuitry that will display, or use for some other purpose, the current information.

Is that what you need to know? If not, please explain things in more detail. Also, please tell us what is your level of electronics knowledge, so we will know where to start.
« Last Edit: April 18, 2021, 01:44:35 pm by t1d »
 
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Offline m.jayid

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Re: current sensor
« Reply #2 on: April 18, 2021, 02:01:46 pm »
Thank you for your answers .
I am not very much familiar with electronic.
In fact I would like to know what is the relation between the input of the amplifier and its output.
What is the purpose of C77 .
What is the cutoff frequency of the filters used in the circuit.
Thank you  .
 

Offline strawberry

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Offline Stray Electron

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Re: current sensor
« Reply #4 on: April 19, 2021, 01:02:05 pm »
   I'm confused. Are the two circuits shown in the first photo supposed to be the same? They're NOT! 

    Figure 238 shows pins 1,2 and 3 all tied together but in figure 239 they are the output, - input and input respectively.

    The device that you show in the second photo (you don't show it's part number) may be nothing more than a current transformer and MAY not contain any active circuits.  Without a part number and a complete description it's impossible to tell.

   In the circuit in figure 238, the line being monitored appears to attach directly to 6 pins in the device but the part in the second photo the insulated line being monitored simply passes thru the the device and doesn't connect to it electrically.

   You're not even comparing apples and oranges, this is more like Apples, rabbits and tennis balls! Except for the fact that they monitor current, none of these circuits have much in common.

   C77 is there to dampen the feedback of the op amp.  It's a common technique, look it up. Get the data sheet for the part it should tell you how to calculate the cut off frequency, but be aware that the cut off will be gradual and not abrupt. These simple one pole RC filters are only intended to block high frequency noise that is orders of magnitudes higher in frequency than the expected signal.
« Last Edit: April 19, 2021, 01:26:40 pm by Stray Electron »
 


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