using 35v Transformer?
I have a Centre tapped Toroidal here, two sets of 35V / 4,3A = 2 x 208Watt
so i was wondering if its possible i can use this for the F5 if i use half the winding then i could get two sets of 17.5v ? which seems perfect to me, i dont know of any other way to get ~18v i need from this transformer.
Cheers Riki
I have a Centre tapped Toroidal here, two sets of 35V / 4,3A = 2 x 208Watt
so i was wondering if its possible i can use this for the F5 if i use half the winding then i could get two sets of 17.5v ? which seems perfect to me, i dont know of any other way to get ~18v i need from this transformer.
Cheers Riki
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Hi sorry im not that knowledgeable in electronics, basicly is it possible to use only one half of transformer for example..
just use 15volts rather than the full 30, its basicly a 35v transformer i have so i need half that for the F5 psu i think, and i also do not know the drawbacks to doing this if it works, im probably posting in the wrong place for newbie questions lol
I previously built the lovely sounding Zen V4 amp by Mr Pass, but just feel a bit uncomftable with the Psu side of things!
just use 15volts rather than the full 30, its basicly a 35v transformer i have so i need half that for the F5 psu i think, and i also do not know the drawbacks to doing this if it works, im probably posting in the wrong place for newbie questions lol
I previously built the lovely sounding Zen V4 amp by Mr Pass, but just feel a bit uncomftable with the Psu side of things!
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Solution is easy - move to USA or other country with 115v mains, and the transformer will be perfect voltage. 
A bit small VA though
A bit small VA thoughive just answered my own question
2 secondarys
PRI = 230v ac Brown-Blue
SEC 35v ac / 4.3A
SEC 35v ac / 4.3A
two secondarys with no centre-tap, i got it wrong basicly i cant use this with the F5 as the voltage is way to high! hah u learn!
The problem can easily be solved by splitting the single rail with too high voltage into splitted rails using a simple discrete virtual ground circuit, e.g. :
Virtual Ground Circuits
I have used the Sijosae circuit in the above link successfully in my very first 4-FET Aleph-X. You just need to use high power BJTs instead of those small signal devices in the schematics. In my (antique) version, the bias was set at 200mA.
The circuit based on a single BUF634 is also a good one and easy to build.
Patrick
Virtual Ground Circuits
I have used the Sijosae circuit in the above link successfully in my very first 4-FET Aleph-X. You just need to use high power BJTs instead of those small signal devices in the schematics. In my (antique) version, the bias was set at 200mA.
The circuit based on a single BUF634 is also a good one and easy to build.
Patrick
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I'm done taking photos and such and then I'm off to the coast to write
the text. This and the F6 will be done before the end of the month.
There are several versions of the F5 TURBO.
Lots of room to play.
Thankyou so much for the wonderfull sounding amplifiers! the enjoyment for me bulding them, i liked electronics as a child but have realy been first and foremost a musician but had to build the amps and they proved to provide me with the natural sound i needed to mix my own songs
EUVL, thankyou ! im off to the pub to play some music with the band but after shall check this out, thanks muchly!
From spec sheet the FQP TO 220 has much more current capability than the
FQA counterpart
I think is down to the construction methods that are different for P and N channels.
Current for FQP is 19 A for the FQA 12 A.
Agree with you it is scary to use a TO 220 but whit due care and hard work I have been running them for the past 4 months.
Papa said that for the litle ones 40 W is the limit for the larger ones 50 W
I have used Kerafoll 86/83 (as far as I know it is the best interface material for performance) Bar clamps to increase the pressure on the Mosfets
Large cooper heath spreaders and same rather big heat sink.
I believe that the most important thing to wach out for is the Junction themperature, the drain pin is directley conected to this and mesuring close to the mosfet body can give a prety accurate temperature mesurament of the Junction itself .
I am running 2 paralell mosfet at 2.6 A 26 V
1.3 X 26 = 34 W so no where near the 40 W limit.
to look at this another way
supose you have 2 similar amplifiers (same current voltages and sinks)
One use perfectley adequate mica and goop and one 3mm screw to clamp the lot togheter, the sink, supose, will be warm
The second amplifier uses better thermal coupling for the mosfets say for argument sake 1/2 of the previous one
still a warm sink but what will be the Junction temperature?
I have (only way to get them for me ) 100 off each. (less the one I am using)
So for matching pairs I recon 100 is enough ?
I did match the mosfets at 2A 24 V and keeping the temperature of the DUT at 50 C (VGS is temperature dependent)
I made that offer not for making a profit and it stand as that.
I was going to post spec shets but PDF files to large.
There may be other merits of the smaller TO220 case such as lower capacitance and such that may make this a better choice.
I can hardly spell corectley so I will refrain from reading Data sheets
Papa
should I post real F5 TURBO plan , for Greedy Boyz ?
no foolin' this time .......
Yeah and you think I am going to fall for that again...
Yes please (be funny any way) and then I may be wrong and you relly got the real thing this time.
I'm done taking photos and such and then I'm off to the coast to write
the text. This and the F6 will be done before the end of the month.
There are several versions of the F5 TURBO.
Lots of room to play.
Tanks Nelson
"severall version"
Yess please.
Papa
should I post real F5 TURBO plan , for Greedy Boyz ?
no foolin' this time .......
Please do
