The "Big Thing" - Ed Sommer - Tweakers' Asylum

The "Big Thing"

24.3.80.6

Posted by Ed Sommer on July 20, 2000 at 10:47:16

In Reply to: Re: No doubling measured posted by Jon Risch on July 18, 2000 at 19:09:10:

I have no interest in using C-M chokes in surge protectors. I agree with you on standard rod wound inductors for that use. I don't like to hear that C-M chokes cause double the output voltage when hit with a diff. spike, because they don't. I agree that current flowing in one winding will induce a voltage in the other winding, thats the whole idea of the C-M choke, but it will not cause a double of voltage.

Think of it this way, the top coil receives the spike, the spike is above ground in voltage, (or below if you want to think of a negative going spike), and it wants to flow to ground. So it is an un-balanced voltage and it is ground referenced. Well the voltage that was induced in the other coil is BALANCED voltage it only wants to flow back to the other side of its own coil, not to ground. Trying to flow to the other side of its own coil it will have to go thru the top coil and will be choked out because it is a common-mode signal, (remember it IS balanced) and that is what a C-M choke does.

The other point on why it will not double is the caps on the output shunting the spike to ground and providing a ground ref. point at the output of the winding.

This was not an attack of you or your surge supressor, it was just to defend common-mode chokes. They are VERY important in low RFI power supply design and I don't want people to be afraid to use them because they think they are going to double the voltage.

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Follow Ups Full Thread

Topic - REVIEW: DIY by Jon Risch AC filter according to JR Power Conditioner/Surge Protector Review by Lukasz F. at Audio Asylum - Lukasz F. 10:03:53 07/15/00 (22)

DIY AC Filter Design Info - Jon Risch 11:36:29 07/15/00 (21)

Suggestion for you web page, Jon - J Epstein 10:55:11 07/21/00 (1)

Re: Suggestion for you web page, Jon - Ed Sommer 12:50:29 07/21/00 (0)

Please explain doubling - Ed Sommer 16:52:58 07/15/00 (16)

Re: Please explain doubling - Jon Risch 19:54:17 07/15/00 (15)

Re: Please explain doubling - Ed Sommer 09:54:14 07/16/00 (14)

Re: Please explain doubling - Jon Risch 22:21:38 07/16/00 (13)

No doubling measured - Ed Sommer 18:40:17 07/17/00 (7)

Re: No doubling measured - Jon Risch 19:09:10 07/18/00 (6)

The "Big Thing" - Ed Sommer 10:47:16 07/20/00 (4)

Re: The "Big Thing" - Jon Risch 16:58:10 07/21/00 (3)

Re: The "Big Thing" - Ed Sommer 10:47:23 07/22/00 (2)

Examples - Pete Fleming 18:32:28 07/22/00 (1)

Re: Examples - Ed Sommer 10:30:15 07/23/00 (0)

Re: No doubling measured - Ed Sonner 10:38:31 07/19/00 (0)

Re: Please explain doubling - john curl 10:58:22 07/17/00 (1)

Mr. Curl - Ed Sommer 10:31:15 07/18/00 (0)

Still can't see doubling - Ed Sommer 10:30:34 07/17/00 (2)

Re: Still can't see doubling - Allan Moyse 22:25:49 07/18/00 (1)

Re: Still can't see doubling - madalo 16:34:30 07/21/00 (0)

Re: DIY AC Filter Design Info - Lukasz F. 12:37:51 07/15/00 (1)

Input cap is important - Ed Sommer 17:08:57 07/15/00 (0)

Follow Ups

The "Big Thing" - Ed Sommer 10:47:16 07/20/00 (4)

Re: The "Big Thing" - Jon Risch 16:58:10 07/21/00 (3)

Re: The "Big Thing" - Ed Sommer 10:47:23 07/22/00 (2)

Examples - Pete Fleming 18:32:28 07/22/00 (1)

Re: Examples - Ed Sommer 10:30:15 07/23/00 (0)

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