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Old 3rd February 2004, 05:29 AM   #1
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Default Hammond PT and KT88 Design costs.

I was considering using one central PT in this power supply schematic from a 400-0-400 Hammond PT with double the asked-for per-channel current requirements.

Each side asks for 230mA, I intend on using one single 400-0-400 Hammond tranny with 465mA total load.

Would it be possible to keep all components post-tranny in this design the same and just make a central tap for both sides power draw?

The original PSU schematic: http://www.plitron.com/images/Diagrams/vtvkt882a.gif

I have removed the -80v power supply for now so as to simplify the nitty-gritty, I intend on making the -80v supply with a seperate PT later on as all the Hammond transformers have 50v only. not 70v.
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Old 3rd February 2004, 06:02 AM   #2
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LoL wait a minute, isn't that a dead short across the secondary? :P
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Old 3rd February 2004, 06:08 AM   #3
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I've had too much sugar this morning

I think I'll scratch this one rather than figure out why I can't do it... and just go along with two psu's in two chassis with two completely seperate components and front-end amplifiers with seperated chassis earths.
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Old 3rd February 2004, 06:49 AM   #4
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Why not ground the centre tap, then feed each 400v winding end to a separate bridge rectifier?
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Old 3rd February 2004, 07:05 AM   #5
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Hmm, I'll think about it!

Thanks dhaen

Any hints or ideas is much appreciated.
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Old 3rd February 2004, 07:16 AM   #6
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No that won't work, now if I done that then both neutral of the rectified side and neutral of AC side would be the same!, Ie complete meltdown.
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Old 3rd February 2004, 07:17 AM   #7
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Unless I removed the filter caps from ground and placed them on neutral of the rectified side of each channels PSU circuitry.

However I am puzzled as to what will happen with the filament supplys and their associated unmodified 220r and caps, what effect will those see.

Like this:
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Old 3rd February 2004, 07:39 AM   #8
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Quote:
No that won't work, now if I done that then both neutral of the rectified side and neutral of AC side would be the same!, Ie complete meltdown.
Oops you're right... too early in the morning

Why use a bridge rec at all? Why not just 2 diodes, as the transformer was designed for?
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Old 3rd February 2004, 07:40 AM   #9
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I don't know how to use only two diodes with a CT PT...

Care to show me? :P

This is one side of the original PSU schematic for comparison:
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Old 3rd February 2004, 07:44 AM   #10
dhaen is offline dhaen  Europe
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