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Old 21st May 2012, 09:48 PM   #41
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Quote:
Originally Posted by SRMcGee View Post
buzzforb:

You are apparently going to use Antek's AN-6224. Antek also offers 800VA and 1000VA toroids with 25V secondaries. Can you help me understand why the risks associated with the extra 1 volt are more compelling than the advantages of either of the significantly larger transformer alternatives?

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i belive it is more the 600VA option
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Old 21st May 2012, 09:49 PM   #42
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Originally Posted by dimkasta View Post
For now I will stick to 18V toroid, 23V rails and 1,3A per channel.

Too many things can go wrong and I do not feel confident yet experimenting.

I m still considering the huge toroids though
sounds wise just haul out if you need help
thats the reson we're here
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Old 1st June 2012, 12:16 AM   #43
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I have been a bit silent cause of of too much crazyness going on at work...

Currently trying to decide what caps to get for the PSU.
I have the store's PSU boards and I am thinking of using all 12 cap positions by soldering 4 on the bottom side and 8 on the top side.

Something that is bothering me is selecting the voltage between 35V and 50V. The rails are going to be ~23V (18V socondaries) so either should be adequate.
The 35V dimensions will allow for 4x33KuF + 8x22KuF = 308KuF
The 50V dimensions will allow for 4x22KuF + 8x15KuF = 208KuF

I am seriously considering the 308KuF @35V option (it s about 15euros more expensive)

The drawbacks are that I am going to need double the space in the chassis and that mounting the board on it will be a bit trickier.
I will also probably need a soft start (which I already have anyway, again from the store).

Any suggestions or comments?

Last edited by dimkasta; 1st June 2012 at 12:23 AM.
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Old 1st June 2012, 12:28 AM   #44
6L6 is offline 6L6  United States
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Both the 35v and 50v caps are more than enough rating for the project. Pass himself uses 25v caps in the factory F5.

Both of your capacitance ranges are more than enough, and will work quite well. Again, looking to the factory-build F5, it uses 120,000uf total, or 60,000uf per rail.

The CL-60 thermistors are the soft-start protection in the original circuit, but as you surmise, with 300,000uf of capacitance in the circuit, a 'more official' soft-start might be appropriate.
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Old 1st June 2012, 10:07 AM   #45
AndrewT is offline AndrewT  Scotland
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The capacitance requires a slow charge circuit.
The transformer requires a soft start circuit.
The two circuits are different.

One can cobble together a combined circuit that does both jobs, but the slow charge part is severely compromised by being fitted on the primary side. Slow charge should be fitted on the secondary side.
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Old 1st June 2012, 10:19 AM   #46
Zen Mod is offline Zen Mod  Serbia
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yeah

over-engineering is way to go

living in Athens , with European (220-240Vac) mains , means that 10-15R/10A NTC (placed in primary side , of course) will perfectly do the job

if more conservative , then "classic" soft start gadget circuit but with NTC's instead fixed resistors - will be perfect and really soft start solution .

usual ones , with fixed resistors , aren't universal solution ...... charging time must be tweaked to ensure non-sparking of shorting relay contacts ; using NTC's instead fixed ress. , especially with prolonged delay , will ensure long life and proper operation of shorting relay contacts
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Last edited by Zen Mod; 1st June 2012 at 10:32 AM. Reason: hickups
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Old 1st June 2012, 10:50 AM   #47
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Any specific suggestions for the 10-15R/10A NTCs ?
I looked on mouser, but I cannot find anything in those ranges.
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Old 1st June 2012, 10:57 AM   #48
AndrewT is offline AndrewT  Scotland
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CL60 is perfect for a high power 110/120Vac primary.
Put one CL60 on each of these primaries and you have an excellent soft start.

This shows in some of Pass schematics. The two 110/120Vac primaries have a CL60 on each.
When you need to series connect the 110/120Vac primaries for 220/240Vac operation, you still need the two CL60. This time the CL60 are effectively in series.
Note that in both supply situations the CL60s are NEVER in parallel.
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Old 1st June 2012, 11:02 AM   #49
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I remember from the Turbo article, Pass recommended CL30 ones. sorry for being a noob, but I don t know their difference.
ps
I m on a 220/240V grid.
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Old 1st June 2012, 11:06 AM   #50
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Download the datasheets.
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