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Simplistic Mosfet HV Shunt Regs
Simplistic Mosfet HV Shunt Regs
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Old 3rd July 2012, 07:44 AM   #3081
Salas is offline Salas  Greece
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Simplistic Mosfet HV Shunt Regs
As a plain inductor then. That's loading it no doubt. How much bias current your preamps run on 26 tubes? 6+6mA or 10+10mA?
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Old 3rd July 2012, 08:28 AM   #3082
vgeorge is offline vgeorge  Greece
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Simplistic Mosfet HV Shunt Regs
About 6mA per tube. I have my shunts set at 40mA, one per channel.
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Old 3rd July 2012, 02:28 PM   #3083
albertli is offline albertli  Canada
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Salas, George,

OK 40mA for the reg.
Yes my power amp with 100k input and I'd like to try anything recommended for I want to pull the best from both opt and the reg. I'd firstly try using the primary as choke with Murdorf silver/gold 0.47 then go on with resistive load so to compare.
Will report asap.
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Old 5th July 2012, 01:39 PM   #3084
albertli is offline albertli  Canada
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Salas & George,

Has done the compare with the RC & LC. I still like the LC, only 100H with 1660 10mA, it sounds a bit smoother to me. I need more higher B+ for the RC 22k load. RC measured a bit better with square wave up to 7K, 10k still acceptable and turned really ugly above 12k. LC is good up to 5.5k, sounds more open and not that congest/compress as 4.5:1. It also looks good down to 50 Hz. I'd like to try the LC route further with higher inductance choke, 200-300H. Will the reg handle the total of 600H, or I'll need another reg for the other channel ??
Albert
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Old 5th July 2012, 04:49 PM   #3085
vgeorge is offline vgeorge  Greece
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Simplistic Mosfet HV Shunt Regs
100H is a bit low for the #26. I use the 1660pp which is more than 200H.
You can always put two chokes in series.
The reg can handle the total current for two channels, even if you use more induction, but two is better than one.
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Old 6th July 2012, 05:41 AM   #3086
albertli is offline albertli  Canada
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Thanks George,
I have couple 0.22 FT-3 teflon on hand, would compare with the Murdorf silver gold. I already put the order for 4 156c chokes, and would try to follow Andy's route with 2 156c in series. Will let you know asap.
Albert
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Old 22nd July 2012, 10:55 AM   #3087
studiostevus is offline studiostevus  Netherlands
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Ok guys, help me in my thinking:

I have just designed, etched and soldered my first Salas HV shunt reg (SSHV2). I would like to use it in a line stage, which will be a ~12mA load @ 200V. Hence I use a 15K dummy load (200/0.012=16.6K).

My raw supply is as follows (dual mono):
Transformer -> EZ80 -> CLCLC (-> SSHV2)

On the 100K bleeder resistor I am using, the PSU gives 220V.

When I attach the SSHV2 with a 15K load, I observe the following:
- SSHV2 led goes on (that's a good sign!)
- Input voltage is 125V... that's less that without load, but so much??
- Output voltage is 125V
- Across R5 (T.P.) I measure 95mV (so 9.5mA CCS)
- Turning any of the pots does not change output voltage/current

Am I missing something? The transformer has 100mA windings so should not be sagging so much....
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Old 22nd July 2012, 10:57 AM   #3088
studiostevus is offline studiostevus  Netherlands
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I would have been pretty proud if it had worked...

The whole reg is mounted on a huge heatsink
Click the image to open in full size.
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Old 22nd July 2012, 11:43 AM   #3089
merlin el mago is offline merlin el mago
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Quote:
Originally Posted by studiostevus View Post
Ok guys, help me in my thinking:

I have just designed, etched and soldered my first Salas HV shunt reg (SSHV2). I would like to use it in a line stage, which will be a ~12mA load @ 200V. Hence I use a 15K dummy load (200/0.012=16.6K).

My raw supply is as follows (dual mono):
Transformer -> EZ80 -> CLCLC (-> SSHV2)

On the 100K bleeder resistor I am using, the PSU gives 220V.

When I attach the SSHV2 with a 15K load, I observe the following:
- SSHV2 led goes on (that's a good sign!)
- Input voltage is 125V... that's less that without load, but so much??
- Output voltage is 125V
- Across R5 (T.P.) I measure 95mV (so 9.5mA CCS)
- Turning any of the pots does not change output voltage/current

Am I missing something? The transformer has 100mA windings so should not be sagging so much....
DC input must be 20VDC higher than Vout target

CCS target must be 20mA more spare for proper regs power consumption to good output impedance spec so setup your CCS current accordingly 12mA target + 20mA shunt needs you must set your CCS to 32mA

Last edited by merlin el mago; 22nd July 2012 at 11:45 AM.
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Old 22nd July 2012, 11:50 AM   #3090
Salas is offline Salas  Greece
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Simplistic Mosfet HV Shunt Regs
Try load your raw supply for ~30mA first, no reg associated. Does it hold?
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