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Old 1st April 2006, 11:25 PM   #1
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Exclamation Questions, aleph, your ideas

Hello All
Back to it, just got myself married and ready to finish off my first project, my Aleph-x

After spending weeks reading thread after thread ive decided just to build it and learn the hard way instead of getting bogged down in facts and figures.

but here are a few basic questions that i must ask
1- Is using a single throw double poll on the phase and Neutral any advantage on switching just the phase on the main incoming?

2-Of the eight mosfets mounted on heatsinks is it better to group resistors with them or mount these resistors on the PCB and running wires to the fets?

3-Using Bleed resistors for the power caps, dont these caps power down through amp after turnoff?

4-When looking at digi-key and looking for say a capacitor, there are so many options, is there a parts list someone has done?


Cheers for any input!!
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Old 1st April 2006, 11:38 PM   #2
jleaman is offline jleaman  Belgium
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Might want to "NOW" ask wife if you are allowed to do this task HHEH


What kinda parts do you need ? Cap's can be expencive. Digi key has them but once again they get $$$ There is a person on this forum that is always selling them Coulomb maybe email him ?
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Old 1st April 2006, 11:57 PM   #3
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I still wear the pants, its just the material is starting to fray.

Ive got some Marcon power caps second hand, tested great.
What I meant was you know the size you need but when doing a search on digikey you get eg 544/p, 544/pw 544/abbsux etc etc.
Just wondering if someones done all the hard work and they have a list of part numbers for aleph-x

Cheers
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Old 1st April 2006, 11:59 PM   #4
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by freakyone
I still wear the pants, its just the material is starting to fray.

Ive got some Marcon power caps second hand, tested great.
What I meant was you know the size you need but when doing a search on digikey you get eg 544/p, 544/pw 544/abbsux etc etc.
Just wondering if someones done all the hard work and they have a list of part numbers for aleph-x

Cheers

Oh ok i see what you mean.. I would still ask anthony as he is really good at this..
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Old 2nd April 2006, 07:59 AM   #5
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Hi,

1. the advantage is that when you turn off the amp there canīt be any mains voltage inside. I donīt see any other advantage and you will still need some kind of soft start.

2. The gate resistors should be at the fets, the source resistors can be placed where you want them.

3. Yes but not to 0V, a small voltage stays and can still cause some nice sparks if the capacity of the caps is big enough. The bleeding resistors can be quite large in value. I used 0,6 watt types (value somewhere between 2k2 and 5k6).

4. There is a parts list from Hifizen (look at the Wiki). There really arenīt that many caps needed in the amp except for the power supply. In the amp 220uF / 25V Panasonic FC will do fine. The compensating caps in the current sources can be anything small (Wima FKP for example) and the 5-10pF in the feedback path could be silver mica or a piece of drilled wire.

William
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Old 2nd April 2006, 09:54 AM   #6
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Thanks William!

Regarding Question 4
C3 and C5 are the current sources (wima fkp)

is C1 and C6 the Panasonic FC?

And another thing, 5w .39R wirewound, good choice for the source resistors, metalfilm seems only to handle 3W in that size, not to sure 3W would handle the jandle

Cheers in advance
Dan
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Old 2nd April 2006, 10:13 AM   #7
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forget the question on capacitors having a blonde day!
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Old 2nd April 2006, 10:22 AM   #8
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Hi Dan,

C1, C6, C3, C5, C12, C13 = 220uF/ 25V Panasonic FC. C1 and C6 can be as low as 6,3V.

C9, C10 = 2n2 - 4n7 wima fkp

C2, C8 = 5-10pF silver mica

C7, C8 is not needed in my amp but would also be Wima FKP

3watt is more than enough (0,39R is enough for 2.8A (eff) per fet!) so I would go for a metalfilm, not a wirewound.

William

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Old 5th April 2006, 11:08 AM   #9
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Thanks william!!

This may be a silly question, prepare yourselfs
Now Schottky retifies, ive used two pin recs but never three pins.
Is there two recifiers in one with a common pin?
this recifier has the case type TO-220AB rated at 10A and 45V


So if thats the case and Im using dual bridge per mono Id need a total of 4 per channel

Cheers in advance
Dan
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