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6V6 line preamp
6V6 line preamp
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Old 22nd March 2018, 01:15 PM   #3331
vgeorge is offline vgeorge  Greece
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6V6 line preamp
Everything uses feedback.
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Old 22nd March 2018, 01:20 PM   #3332
merlin el mago is offline merlin el mago
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Quote:
Originally Posted by vgeorge View Post
Everything uses feedback.
What part of the schematic is the feedback?
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Old 22nd March 2018, 01:48 PM   #3333
Salas is offline Salas  Greece
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Its not the usual loop you see in an amplifier with one resistor coming back from the output and another going to ground, but the small transistors in the regulator react to voltage changes at Vout vs the VRef due to load play and drive the output Mosfet to compensate by adding/removing current to the load, yes? That is feedback. Watching and reacting to a situation. When you write a post in this thread you watch the screen and your fingers run on the keyboard following your thought by your brain overseeing that loop and if they error you delete and replace letters. This is feedback too.
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Old 22nd March 2018, 01:56 PM   #3334
skrstic is offline skrstic  Serbia
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Thanks Mr. Salas.

Quote:
Originally Posted by Salas View Post
Also use IXYS higher voltage DMOS instead of DN2540 Q1 for more safety since the Vinput is close to the DN's limit in this application. Nikos will kindly remind us the exact IXYS type he put.
This IXYS IXTP08N100D2?
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Old 22nd March 2018, 02:09 PM   #3335
Salas is offline Salas  Greece
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Yes that was the one
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Old 22nd March 2018, 02:16 PM   #3336
skrstic is offline skrstic  Serbia
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do not have it in farnell or locally. Can IXTP4N80P http://export.farnell.com/ixys-semic...427372?st=IXTP be replacement? Or IXTP8N65X2...

Last edited by skrstic; 22nd March 2018 at 02:19 PM.
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Old 22nd March 2018, 02:20 PM   #3337
Salas is offline Salas  Greece
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No, the one you linked is a usual enhancement mode MOSFET i.e. it will not be normally on and self bias, needs external bias voltage and its normally off. You look for depletion mode N channel types.
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Old 22nd March 2018, 02:50 PM   #3338
Salas is offline Salas  Greece
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You can alternatively try make SSHV1 on general board though, that uses usual enhancement mode types: Simplistic Mosfet HV Shunt Regs

If you could find a higher voltage P type for its Q1 (with not too many pF Ciss to avoid slow down much) it would also be safer than the original.
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Old 22nd March 2018, 03:01 PM   #3339
merlin el mago is offline merlin el mago
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Quote:
Originally Posted by Salas View Post
Its not the usual loop you see in an amplifier with one resistor coming back from the output and another going to ground, but the small transistors in the regulator react to voltage changes at Vout vs the VRef due to load play and drive the output Mosfet to compensate by adding/removing current to the load, yes? That is feedback. Watching and reacting to a situation. When you write a post in this thread you watch the screen and your fingers run on the keyboard following your thought by your brain overseeing that loop and if they error you delete and replace letters. This is feedback too.
Very well explained as always, thank you Salas.
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Old 23rd March 2018, 08:54 AM   #3340
nikosokey is offline nikosokey  Greece
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My setup.
640VCT
2X10V /2A for regs 6.3V
5VCT/3A
One reg at 70ma (input 345V-385V) output 330V with IXTP08N100D2
Big heatsing SK129 64mm
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Last edited by nikosokey; 23rd March 2018 at 09:07 AM.
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