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  #11  
Old 01-15-2017, 04:36 PM
yooper yooper is offline
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I'll try to explain this without a picture , where the AC goes to the common point of two diodes you see that the arrow on one diode points one direction and the other diode is opposite direction , this is why you would need 2 reverse polarity diodes , one for each AC input lead -by reverse meaning the threaded end of the diode is opposite polarity of the other diode .
Clear as mud , eh ?
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  #12  
Old 01-15-2017, 04:48 PM
Rufus Rufus is offline
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Originally Posted by yooper View Post
I'll try to explain this without a picture , where the AC goes to the common point of two diodes you see that the arrow on one diode points one direction and the other diode is opposite direction , this is why you would need 2 reverse polarity diodes , one for each AC input lead -by reverse meaning the threaded end of the diode is opposite polarity of the other diode .
Clear as mud , eh ?
Is that how I have it in the diagram I drew?

Thanks
Tim
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  #13  
Old 01-15-2017, 04:53 PM
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How do I upload a image from my computer ? The insert image icon wants to do it from a url link ?
After you write your post go below to manage attachments and use that to attach your pics.
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  #14  
Old 01-15-2017, 04:59 PM
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How do I upload a image from my computer ? The insert image icon wants to do it from a url link ?
Scroll down below your message window, click the Manage Attachments button.
This opens a little window of your computer hard drive that works about like Windows Explorer.
Click the top "Choose File"
Navigate to your picture & click it.
In the lower right corner of the attachments window click "Upload" & wait a few seconds. A thumbnail of your picture should appear below the typing window.

Remember to close the manage attachments window when you're done.
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  #15  
Old 01-15-2017, 05:01 PM
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MAC702 MAC702 is offline
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For a full wave bridge rectifier he will need two separate heat sinks if he has 2 forward and 2 reverse diodes , if the diodes are all the same polarity he will need four separate heat sinks .
Why? That doesn't make sense to me.

A heat sink is a heat sink, not part of the electrical circuit (except probably grounded to chassis.)

Isn't this an example of one on a single heat sink?
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Last edited by MAC702; 01-15-2017 at 05:09 PM.
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  #16  
Old 01-15-2017, 05:05 PM
Rufus Rufus is offline
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Why? I'm going to do some research but that doesn't make sense to me.

A heat sink is a heat sink, not part of the electrical circuit (except possibly grounded to chassis.)

I don't deal with a lot of components like this, but I'm pretty sure I've seen a lot of full-wave bridge rectifiers mounted on a single heat sink.
I don't have that kind of bridge rectifier. I am using 4 separate diodes like this one here. That is why I need 3 different heat sinks. One for the 2 bottom diodes as in the drawing and 1 for each of the top diodes.

Link to the kind of diode I have ordered.... http://www.ebay.com/itm/150A-POSITIV...-/261092065367


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Tim
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  #17  
Old 01-15-2017, 05:05 PM
yooper yooper is offline
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Quote:
Originally Posted by MAC702 View Post
Why? I'm going to do some research but that doesn't make sense to me.

A heat sink is a heat sink, not part of the electrical circuit (except possibly grounded to chassis.)

I don't deal with a lot of components like this, but I'm pretty sure I've seen a lot of full-wave bridge rectifiers mounted on a single heat sink.
Where diode is bolted to the heat sink is part of the circuit , the base of the diode is " hot " .
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  #18  
Old 01-15-2017, 05:12 PM
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So in this case, that diode's heat sink would be insulated from the chassis. Okay that makes perfect sense. That's the key I was missing in my tired brain. Long afternoon. Guess I never thought about how those big diodes were mounted before. Duh.
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  #19  
Old 01-15-2017, 05:17 PM
Rufus Rufus is offline
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I could make the enclosure out of mild steel but have the heat sinks insulated from the enclosure, perhaps mounted on some wood.

Thanks
Tim
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Last edited by Rufus; 01-15-2017 at 05:30 PM.
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  #20  
Old 01-15-2017, 05:41 PM
yooper yooper is offline
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I could make the enclosure out of mild steel but have the heat sinks insulated from the enclosure, perhaps mounted on some wood.

Thanks
Tim
Or .. you could put those diodes on the shelf , take the easy way and order that bridge rectifier that I linked in your other post
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