BAF 2015 Coverage

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Zen Mod

Zen Mod

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OK
as peace sacrifice ...... Mighty ZM wearing Hawkwind Mickey Mouse ears

:devily:
 

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generg

generg

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Three people besides 2picodumps tried to build this PowerMOSFET version with the Jensen.
They had all the current runaway around 2.8A. And they used goop also.

So the problem with this build is not really the goop, but if the circuit can work at all with this IXFN140 and under which conditions.
Nelson showed the circuit and he showed us the distortion and others specs. So he got the circuit working.
Mike did you try to build this circuit with the parts?

Mr. Pass could you please help us a bit coming out of this not moving situation?
 
2 picoDumbs

2 picoDumbs

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Joined 2013
generg said:
Wonderful, first good news!
Click to expand...

I also have wondered about Rob's concern about whether the base pin should be left floating or shorted to ground or tied to the emitter. I've never played with the optocouplers so no idea.
It seems to work in simulation leaving it floating but that could be coincidental.
So far, I'm quite confident this will work.
 
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generg

generg

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Joined 2009
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The Base pin is open in all circuits I know, M2, MU-Monster etc I saw from Nelson.

I know it is seductive to assume there must something connected......:)
I tried this and the only result was that the circuit did not work any longer.

So I wait for the changes that make your build more similar to the BAF2015 circuit.
 
Nelson Pass

Nelson Pass

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Joined 2001
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generg said:
Three people besides 2picodumps tried to build this PowerMOSFET version with the Jensen.
They had all the current runaway around 2.8A. And they used goop also.

So the problem with this build is not really the goop, but if the circuit can work at all with this IXFN140 and under which conditions.
Nelson showed the circuit and he showed us the distortion and others specs. So he got the circuit working.
Mike did you try to build this circuit with the parts?

Mr. Pass could you please help us a bit coming out of this not moving situation?
Click to expand...

The current for the circuit shown is 3.2 amps, so I don't quite know what
you mean by "current runaway at 2.8 A".

If you want lower current, then you need to change the values of the
resistors sensing current for the opto. If the current is exceeding 3.2 amps
(about 10% tolerance) then I think you want to check all the voltages
and maybe look at it with an oscilloscope to see if it's motor-boating
(will tend to do that with cap coupled source), oscillation at high frequency
or something else.

If it's high frequency oscillation I would look at the stopper resistor values.

If it's motor-boating, check stability with input shorted to ground.

I recall Flocchini experienced problems, but as of 2/10 they seem to have
gone away by themselves.

:cool:
 
M

Michael Rothacher

Pass DIY Apprentice
Joined 2001
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No one said the goop was the issue.

I said it was wise (if not mandatory) to use it. And, duh, it is.

Here's the current source end of my BAF Amp test thingamajig.

It works like glue by the way :)

Chill.
 

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