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Old 2nd February 2004, 01:25 AM   #1
elizard is offline elizard  Canada
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Default Aleph 3 questions

Got a few questions about building an aleph 3. Trying to make up my mind as to what the best value for money amp will be for me to build
(Btw, has to be an aleph 3 since I've a suitable transformer, 400va 2x22v)

Do i need the 2.2mH inductor for the PS? What are the drawbacks of not using it?

Where can I obtain more affordable PCB's than through kristijan (they'd cost me over $70CDN! trying to do this on a tighter budget!).
Or should I just build this on some protoboard?
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Old 2nd February 2004, 05:37 AM   #2
elizard is offline elizard  Canada
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Oh yeah, and the inductors used are simply wire wound correct? If so, is there anything prohibiting me from winding it myself? Wouldn't be too hard to set up a simple jig, wind it, then enamel it, right?
Or should i stop being cheap and buy them (parts express has ones for $10 each, 2.2mH)
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Old 2nd February 2004, 10:59 AM   #3
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Hi elizard,

leave the inductor out, the commercial Alephs dont use it either.
I built mine without inductor, too, and theres no hum. Only when getting about two inches in front of the loudspeaker with your ears you can hear some.
You can also save space without it.

It is easy to build up the aleph3 on a standard board, like this
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Old 2nd February 2004, 04:12 PM   #4
elizard is offline elizard  Canada
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Sweet, both questions answered

What about thermistors and inrush current suppressors? Do I need both of those?
As well, can someone post links (or part numbers) for either mouser or digikey for suitable ones?

Thanks again

(just trying to get an idea of how much it'll really cost in the end. gotta plan this right if i wanna do it so that i dont' run out of money)
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Old 2nd February 2004, 05:57 PM   #5
moe29 is offline moe29  United States
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Digikey part # KC006L-ND Inrush Current Limiter (thermistor)

Nice to have, makes things a bit easier on your PSU. You loose
maybe a volt or so off your rails with it. This part is also seen in
the BZLS article: Earth ground from the AC cord is attached to the chassis for
safety, and is connected to the circuit ground through a power thermistor
(bright idea from Frank DeLuca). This gives some resistive isolation for
prevention of ground loops but goes to small values of resistance in
case of catastrophic connection to the live AC line.


(even if you don't build the ZEN projects, you learn lots of neat stuff reading them!)

m.
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Old 2nd February 2004, 07:56 PM   #6
elizard is offline elizard  Canada
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Awesome, all my questions are getting answered

Thank you.

But I've more ..

The 0.47R resistors, is 3watts ok?
Is a 400VA with 22V on secondaries transformer ok? Or will the rail voltage be too high?

Also, I'll be using 6 33,000uF caps, so that should be enough.

I'm sure i'll have more q's by the end of the day

Thanks again, and I'll make sure to read the zen articles as soon as I have time (i read a couple, but wasn't able to concentrate on them fully, i'll re-read!)
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Old 2nd February 2004, 11:09 PM   #7
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3 watts is OK

You could use a bigger transformer, so maybe it will load
down a bit and you'll get what you want anyway. Otherwise,
I wouldn't worry as long as the temperature is reasonable.
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Old 2nd February 2004, 11:11 PM   #8
elizard is offline elizard  Canada
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The temperature rise should be no more than 25C (I'm using a slightly scaled down version of heatsinks i was going to use for an Aleph 5).

The reason I'm using a 400VA transformer is because that is the one I have on hand. Sadly, purchasing another transformer will cost me $120+ after shipping and tax
So, I chose to make use of what I have around
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Old 3rd February 2004, 12:04 AM   #9
Asen is offline Asen  Bulgaria
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Default About the 0,47 Ohm resistors in Aleph 30

I have MO - 2W and carbon film resistors - 3W on hand. I'm in doubt which ones to choose as far as these are supposed to be MO - 3W. Will 2W be OK? My simulations show they should dissipate 4 times less power.

Thanks
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Old 3rd February 2004, 02:31 AM   #10
elizard is offline elizard  Canada
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Oh yeah, and are the rails going to be too high (will be using 22V secondaries)?
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