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Old 10th August 2010, 12:06 PM   #1
GregH2 is offline GregH2  Australia
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Default Building an Aleph 5...two quick questions

So here they are:

1) For the 1 ohm (power mosfet source resistors) and 0.47 ohm ( x4 output resistors), is a 5 watt rating for each sufficient?

2) What kind of capacitor is recommended for the 680pf and 10pf caps? Silvered Mica, Ceramic?

Your advice is most appreciated.

Greg.
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Old 10th August 2010, 12:47 PM   #2
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Hi Greg,
5W is plenty, I used 3W mil spec. Dissipation is less than 1W.

I can't remember any discussion about those caps, I used silvered mica.
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Old 10th August 2010, 01:06 PM   #3
GregH2 is offline GregH2  Australia
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Thanks Bill. My simple calcs using ohms law suggested the same thing but I found a design on the web that used 10W resistors so I thought I'd better check
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Old 10th August 2010, 02:07 PM   #4
galop is offline galop  Slovenia
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1.enough (maybe try metalfilm 2w)?
2.silver mica
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Old 10th August 2010, 04:33 PM   #5
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Oh yeah, it will bias higher than your paperwork says so don't get nervous unless your heatsinks are marginal.
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Old 26th August 2010, 02:21 PM   #6
GregH2 is offline GregH2  Australia
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Hi Guys,

I actually am building an Aleph 2 now, but thought I would post this question here rather than start a new thread.

Just wondering if 0.5 watts is a high enough rating for the 9.1v zener diodes used to bias the input current source and protect the input fets from static?

Your advice is appreciated.

Regards,

Greg.
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Old 26th August 2010, 02:37 PM   #7
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Should be fine for rails under 2000Vdc.
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Old 17th March 2011, 09:09 PM   #8
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hello.

i am having problems with my Aleph-5.
actualy, it is the power suply what is giving problems.
i am using 2X30v what gives me 40.8v after reg.
is this a problem and if so, what can i do to get it right?
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Old 18th March 2011, 08:18 AM   #9
h_a is offline h_a  Europe
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Sounds a bit like you bought a 30VAC toroid that gives 30xsqrt(2)=42.3 VDC as output voltage (minus 1.4 V of the recitfier bridge plus the voltage regulation of the toroid).

If so, you can either use the higher voltage to feed your Aleph5 (and lower bias to get power dissipation down, maybe not so nice option) or get a 21 or 22 VAC toroid.

Hannes
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Old 18th March 2011, 09:42 AM   #10
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the toroids do give 2 x 30v and i do whant to use them.
i bought it all together as a set from someone who did not have the time to finish the project.
so if it is possible to use the, then i would like to know how to lower the bias.
i am using the pcb from KK.
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