Simplistic Mosfet HV Shunt Regs - Page 406 - diyAudio
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Old 17th August 2013, 06:00 AM   #4051
stajo is online now stajo  Sweden
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My start for removing HF noice would be a small, 10 nF or so 1000 V poly or silver mica right after the rectifiers. Even more effective would be to use (C)-L-C choke input and start with the 10 nF. In practice it would act like choke input (DC=0,9xAC). Very effective also for HF
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Old 17th August 2013, 06:47 AM   #4052
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Quote:
Originally Posted by merlin el mago View Post
In my PSUDII simulation the last RC 1 ohm 3uF just before the load increase the ripple.
Circuit is oscillating. Increase last R from 1 to 10 Ohm

But really. Trying to combine DHTRobs passive filter layout with active filtering changes the whole idea. I think you should ditch that. Putting resistance after the shunt just puts their good job in the closit. Short twisted wires directly as close to the load as possible from shunts, nothing inbetween. If HF noice/trancients is a problem, try decoupling near bridge.

Last edited by stajo; 17th August 2013 at 07:05 AM.
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Old 17th August 2013, 07:25 AM   #4053
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Sims 1 and 10 ohms for visualisations
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Old 17th August 2013, 08:41 AM   #4054
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Quote:
Originally Posted by Salas View Post
Just change the sensing resistor to 1 Ohm now. Looks like it will push the borderline just so that may prove a good help.
Right, so got this now sorted and is working like a charm. Increased raw supply to allow output voltage increase but small drop in the CCS, changed CCS FET and added bigger heatsinks to minimise temperature drift at maximum current. To run this regulator at 85-90mA you need them clearly! Thanks for the tips
See further notes here: Adjusting the shunt regulator | Bartola Valves

cheers,
Ale
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Old 17th August 2013, 09:24 AM   #4055
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Quote:
Originally Posted by stajo View Post
My start for removing HF noice would be a small, 10 nF or so 1000 V poly or silver mica right after the rectifiers. Even more effective would be to use (C)-L-C choke input and start with the 10 nF. In practice it would act like choke input (DC=0,9xAC). Very effective also for HF
Can't do it because I need B+ before SSHV2 minimum 300VDC

Quote:
Originally Posted by stajo View Post
Circuit is oscillating. Increase last R from 1 to 10 Ohm

But really. Trying to combine DHTRobs passive filter layout with active filtering changes the whole idea. I think you should ditch that. Putting resistance after the shunt just puts their good job in the closit. Short twisted wires directly as close to the load as possible from shunts, nothing inbetween. If HF noice/trancients is a problem, try decoupling near bridge.
If I increase resistor value change the filter value

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Sims 1 and 10 ohms for visualisations
Also you reduce ripple if you increase the value of last capacitor but the same problem like resistor = value of filter will change
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Old 17th August 2013, 09:25 AM   #4056
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I think I'll let it go and run without filter
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Old 17th August 2013, 09:35 AM   #4057
stajo is online now stajo  Sweden
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How did you conclude that you have a HF noice problem? How does it look like, what is the frequencys? Or is it a Citroen-thing: Beautiful solutions to none existing problems
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Old 17th August 2013, 09:38 AM   #4058
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Because in other PSU for other load I compared with or without filter and my ears prefered with filter.
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Old 17th August 2013, 09:52 AM   #4059
Salas is offline Salas  Greece
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Quote:
Originally Posted by mogliaa View Post
Right, so got this now sorted and is working like a charm. Increased raw supply to allow output voltage increase but small drop in the CCS, changed CCS FET and added bigger heatsinks to minimise temperature drift at maximum current. To run this regulator at 85-90mA you need them clearly! Thanks for the tips
See further notes here: Adjusting the shunt regulator | Bartola Valves

cheers,
Ale
Happy end then. And a nice documentation of the proper utilization moves. Congrats.
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Old 17th August 2013, 04:00 PM   #4060
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Quote:
Originally Posted by merlin el mago View Post
Because in other PSU for other load I compared with or without filter and my ears prefered with filter.
This in itself is no evidence for the presence of HF noise. It may stem from various reasons.
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