Electrical Engineering Stack Exchange
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Questions tagged [common-mode-choke]

A type of choke in which two coils are wound on a single core in order to pass differential currents while blocking common mode currents.

A type of choke in which two coils are wound on a single core in order to pass differential currents while blocking common mode currents. See Wikipedia's information about common mode chokes.

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Common mode choke - symbol and orientation

I was wondering why there are different symbols for common mode chokes and if/how they affect the way I have to connect them. (Upper image is incorrect but left here for understanding the comment from @Felthry) Most often I see type 1 and there is…
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Using CM Y capacitors after CM chokes

Below shows the effect of a CM choke on the CM interference: And below is a CM choke with ferrite ring for a USB cable(there is no capacitor installed): In above examples there are no Y caps to earth ground installed yet the CM choke seems to…
cm64
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Common Mode Choke question

I have one question which I encountered during usage of common mode choke. Question : "If a common mode choke is used on the main power / ground input, ensure that no I/O circuits effectively bypass the ground side of the common mode choke. For…
user220456
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Can a common mode choke be used at the output of an SMPS?

If there is CM EMI on DC power supply lines, can a CM choke be used at the output of SMPS supply? Im asking because all CM examples I saw are for AC power lines.
floppy380
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Why are there different ways of winding a common mode choke?

Below shows two types of CM choke winding: Image source: Common Mode Chokes - Basic Knowledge | Würth Elektronik Is there a difference between the two in application? They are both used in literature, yet I haven't seen a single sentence about the…
floppy380
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Common mode choke - short?

I am experiencing weird behavior with a common mode choke and had a few questions. The circuit in question is this: I am using a desktop power supply at 28V and 200mA current. This is the first time I've powered this board. Immediately, the voltage…
jgauthier
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Common Mode Choke Usage

I am using a ACM70V-701-2PL-TL00 Datasheet to attempt to filter out A/C ripple in an in-vehicle audio device. I've run the input 12v through one channel of the choke and I attached the other channel to the same ground pour on both ends. This is not…
t3ddftw
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Common mode choke - alternative part

I have sent out a PCB for manufacture and the manufacturer has suggested an alternative part. The application is a mains powered (220V AC 50Hz) device. The common mode choke is being used to filter EMI on the power lines. The original CMC is a 30mH…
jhorwood28
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Common mode choke selection for 5V 1A smps power supply

I am designing a flyback smps power supply circuit and having trouble deciding the exact common mode choke that I should use. My power supply specs are as follows: Input - 80-270 VAC 50/60 Hz Output - 5 VDC 1 A I found a similar circuit but…
Whiskeyjack
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How does a CM choke reject common-mode noise while allowing the signal of interest?

As far as I know a CM choke is nothing but a transformer(?). How does it block common-mode noise and pass the signal of interest? Should we think of it as an LR filter? And how to size it if we know the signal of interest? A pictorial explanation…
user1245
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