Salas hotrodded blue DCB1 build - Page 135 - diyAudio
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Old 9th September 2011, 10:09 AM   #1341
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by johnwmclean View Post
Andrew for typical 50VA single secondary 15V winding ~1.6A, does one typically half that value to calculate continuous DC output current for ~830mAdc?
The way I have interpreted the manufacturers' datasheet on de-rating for a capacitor input filter, that is what I find.
That continuous DC current from a capacitor input filter ~= 50% of the AC current rating. This allows approximately 70% of the Power that the transformer is rated at and matches well with that de-rating factor I mentioned seeing in almost every transformer manufacturers' data.

A few Members disagree with my interpretation.
But if that de-rating factor is ignored and one tries to draw the full power rating on the DC side, then what effect does I^2R have on the heating of the transformer when feeding high current pulses into the windings? Short higher current pulses that have exactly the same energy as a sinusoidal waveform heat the winding more. That extra heat has to be accounted for. In my opinion that's why the Manufacturers apply the de-rating factor when the transformer is not supplying sinusoidal waveform currents.
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Last edited by AndrewT; 9th September 2011 at 10:14 AM.
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Old 9th September 2011, 10:18 AM   #1342
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Thanks Andrew for the explanation.

Last edited by johnwmclean; 9th September 2011 at 10:25 AM.
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Old 9th September 2011, 06:56 PM   #1343
syklab is offline syklab  Hong Kong
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Hi,
I am try to gether components berfore the board arrive and noted the Vishay Z-foil resistor 220R is very hard to find and none in HK. Can anyone recommend a place to buy this from? Tried Michael Percy but close until October. Also found this Vishay Military Wirewound Resistor 24.3 Ohms 10W 1%, is that good for setting the CCS?

Thanks

Vishay Military Wirewound Resistor 24.3 Ohms 10W 1% | eBay
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Old 9th September 2011, 07:03 PM   #1344
Tea-Bag is offline Tea-Bag  United States
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skylab,
Did you try texascomponents directly?
They make the Z-Foils for Vishay.
TX2575 is the top one.

http://www.texascomponents.com/pdf/Zfoil.pdf
Their email is at the bottom of the document.

Partsconnexion also carries them, but at a higher markup.
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Old 9th September 2011, 07:08 PM   #1345
syklab is offline syklab  Hong Kong
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Texascomponents desn't have a web store for placing order. I guest have to email them.
I will try partsconnexion too.

Thanks
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Old 9th September 2011, 08:25 PM   #1346
syklab is offline syklab  Hong Kong
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Thanks Tea-Bag,

Just placed order with partsconnexion (Vishey for 220R, caddock for 220K, Kiwame for 10R and 3.3R 5W and 4 220R PRP to try out).

Now just need to wait for the parts and board.
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Old 10th September 2011, 05:17 AM   #1347
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Source information

http://www.diyaudio.com/forums/blogs...-resistor.html

Naked Z-foil TX 2575
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Old 12th September 2011, 05:21 PM   #1348
qusp is offline qusp  Australia
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Quote:
Originally Posted by johnwmclean View Post
Not a fan? Well the Buff32 may be better straight into the F5X, but Iím going to give this a crack and see what becomes...
Hey John, nah its not that, love your work as always and the flames are a gas , I assume this was tongue in cheek (and i certainly hope so now ive stuck my foot in it) i'm just not sure I see this as really being balanced, as its just 2 single ended circuits referenced to ground and fed a differential signal. i need to fire mine up (pretty much identical to yours and finally got the iron now, so just need the time for casework)

I will admit i'm a little uncertain of the need for it in your system (or mine thus my snails pace building schedule), but understand the compulsion to build build build and why not when you can produce such nice looking kit.

how are you finding the volumite, i'm interested to hear your thoughts on that after I really pushed it as an option for you. perhaps via email though.
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Old 13th September 2011, 10:34 PM   #1349
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Thanks Jeremy, that makes total sense.

I've been listening through the Beta22 with ears to the grill it's almost impossible to detect the dcb1 in the circuit (all very short cables), which is testament to it's fine transparency. At the moment I'm preferring the DCB1 in circuit, there seems to be an increase in energy, transients seem more relaxed. It's minor, I need more listening time, longer cable runs may pronounce a definite improvement I don't know yet. I'm eager for you to complete yours now, for your impression.
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Old 15th September 2011, 06:19 PM   #1350
syklab is offline syklab  Hong Kong
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Quote:
Originally Posted by AndrewT View Post
irfp240/irfp9140 are a better matched pair than irfp240/irfp9240, if the lower 100Vds limit is acceptable.
Hi Andrew,
Can I use IRFP140/IRFP9140 instead ?
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