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Common mode choke - short?

jgauthier

Mar 22, 2013
54
Joined
Mar 22, 2013
Messages
54
Hello,

I am experiencing weird behavior with a common mode choke and had a few questions.
The circuit in question is this:
1669745792790.png

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 dropped to 0.64, the current went to 200mA and the power supply indicated an overload.

I troubleshot this, down to the TCK0-128 choke.

** So I put this on a bread board. Just a 3 Ohm current limiting resistor and the choke. I get the same results.
First question is what is going on (What am I doing wrong)

As far as I can tell there is no pin indication on the choke. However, looking at the data sheet pin 1 can only be 1 of 2 pins.

1669746900362.png

As follow up questions, I just noticed the dot notation and reading about this seems to indicate that positive polarity should go on the dot.

If that is true, my above schematic may be wrong since 1 is battery ground and 2 is battery positive, where as 4 should be positive and 3 should be ground. This this a concern?

Thanks!
 

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kellys_eye

Jun 25, 2010
5,296
Joined
Jun 25, 2010
Messages
5,296
Input is on 1 and 4, output on 2 and 3. Your connection is effectively shorting the input.
 
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