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Old 3rd October 2006, 10:31 PM   #1
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Default Aleph 3 supercharged

Blues posted this a while ago and dubbed it the A3SC. I'll be utilizing BrianGT's A30/Mini boards; we'll call it the A3/30SC. I want to add another set of outputs, as his design seems to be pushing it to the limit, and Brian's board conveniently allow for 3 sets of outputs. Do I need to adjust any values? Particularly R5 (215ohm) on this schematic. I'll be using IRFP244 for the outputs.
My big 1500VA 38volt trafo, when wired at the primaries for 230V, output approximately 27volts unloaded off the bridge, so far so good. I've realized after playing with the ESP101 for a few months, with my setup at around 150watts, it is simply way too much. And I get to use one of my Aleph 2 chassis, i'm happy, and suffer a serious case of DIY A.D.D. (attention deficit disorder)
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Old 4th October 2006, 12:44 AM   #2
Blues is offline Blues  United States
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Hi Mega-Amp,

Gotta support what I put out there so here goes:

If you'd like to keep the 4A dc bias with 3 fets in parallel you can parallel two 0.75R to get about 1.33A of bias on each branch. This will lessen the stress on the fets at about 32W...still read about "Over Heatsinking". R26 at 2k will keep your ac current gain around the 50% region. For R5 to limit the current at about 12Adc or a negative peak of about 9A , it should be 100R.

I think I miscalculated 215R for a 9A limit as stated in the schematic.
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Old 4th October 2006, 12:57 AM   #3
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Thanks for the support Blues,


The chassis is overbuilt for an Aleph 2, so hopefully I'll be ok.


John.
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