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Old 3rd February 2004, 07:48 AM   #11
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Hmm, I had better get to learning something

Ok so does that design have an output equal to both the 400v taps, ie 800v or does it add current and not voltage?
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Old 3rd February 2004, 08:05 AM   #12
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I think we have it Johnny boy

Excellent so this is essentially what I had to do in the first place to go from a normally tapped transformer to CT transformer :P

Rev 3.
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Old 3rd February 2004, 08:12 AM   #13
dhaen is offline dhaen  Europe
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In this case you could use separate diodes for each channel
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Old 3rd February 2004, 08:31 AM   #14
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Something's telling me this won't work...

Could someone else verify this final plan:

Sorry for all of the image postings but I can't explain it well in text ;\
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Old 3rd February 2004, 12:56 PM   #15
SY is offline SY  United States
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That looks OK. You can lose the 10 ohm resistors- the input cap is reasonably sized, and they'll only waste power and increase ripple. The fusing on the secondary side may or may not be problematic.

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Sorry for all of the image postings but I can't explain it well in text ;\
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Old 6th February 2004, 02:45 AM   #16
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Now everything told me that this schemat does not work, and I was right, it does not work..

I ran a 12v center tapped testbed for this design.

Giving a reading using the center tap as neutral and one of the taps as active on my DMM I was to naturally conclude that it was AC, my DMM correctly displayed 12volts AC and 0v DC.

Now when I placed the diodes into position I got 12volts DC reading off of two of the diodes at which were connected together and 24volts AC out of the diodes!!

Is this normal!?

The transformer is normally rated as 12-0-12...
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Old 6th February 2004, 02:59 AM   #17
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Do I need to have a load on the other two diodes inorder to 'bring the voltage down'?
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Old 6th February 2004, 03:24 AM   #18
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Ahh yes the AC hum, it must be DC because it manages to drive a 12volt load perfectly fine without any overload, infact the transformer is so weak in current that the fan brings down the voltage to 10v and the fan sounds like it is running at 10volt instead of the normal high-squeal 12volts...

So I am therefore concluding that the DMM is merely reading the AC ripple and translating it as if it was true AC, However I am going to check up on this by placing a large 40v capacitor in-line and reading it with an Oscilloscope.
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Old 6th February 2004, 03:29 AM   #19
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Ahh all I was seeing was simple stupidity upon my behalf, it was merely the DMM reading what it should, twice as many volts for a correct reading of half a waveform.
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