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Old 6th February 2013, 06:40 PM   #2471
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Quote:
Originally Posted by merlin el mago View Post
Andy if I not use pot wich value for grid leak resistor 100K?
Anything from 100K to 470K.

Here is an article for choke input. You need to work out critical inductance.
Choke-input power supplies, Part 1 - Henry Pasternack - Tube DIY Asylum

Lcrit = Vdc / Ima

where Lcrit is the minimum (critical) choke inductance, Vdc is the supply DC output voltage, and Ima is the load current in milliamperes.

So Lcrit for 250v and 33mA (e.g. 2 x 26 at 5mA plus regulator at 23mA) would be 7.6 Henries. So a 10H choke would be fine without a resistor to earth after it in this case.

For 2 x 26 at 5mA each and 20mA shunt reg, total 30mA, you need a choke of 8.3H so again 10H is OK.

Last edited by andyjevans; 6th February 2013 at 06:43 PM.
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Old 6th February 2013, 06:43 PM   #2472
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Thank you Andy, BTW Bartolucci 10H 100mA have:
-Regulation 0,5%
-VDC 200
-DC resistance 10 ohms
Are ok?

Last edited by merlin el mago; 6th February 2013 at 06:48 PM.
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Old 6th February 2013, 07:35 PM   #2473
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Ale I have simulated your PSU, simulator saids have more ripple, or I'm misunderstanding something, see attached image.
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File Type: png 2 x 125VAC #26.png (144.9 KB, 326 views)

Last edited by merlin el mago; 6th February 2013 at 07:48 PM.
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Old 6th February 2013, 09:05 PM   #2474
mogliaa is online now mogliaa  United Kingdom
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Felipe, that's not my design. Either way 12mvpp ripple is not bad at all! Are you planning to use a shunt regulator?
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Old 6th February 2013, 10:07 PM   #2475
euro21 is offline euro21  Hungary
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Felipe, can I do some comments?

Such a low transformer DCR not optimal for (mesh) AZ1. It would be better 100-200R DCR.
IMHO C1 low, thus output voltage also low. There are no high charging current (AZ1 unable to do so) therefore increase C1 up to 1-5uF. If output ripple bothering you, increase C3.

ps. PSUD a little cheating, output voltage about 220V, not 230.

Ps2. Attachment is my working #26 preamp (common raw PSU- each side: SSHV2- cascode CCS loaded 26 -TVC) raw HT supply.
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File Type: jpg HT raw supply.jpg (30.7 KB, 299 views)
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Old 6th February 2013, 10:31 PM   #2476
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Euro21 has a fine design there. The only thing I would question is not using polypropylene caps, especially as the last cap. Maybe the 220uF is polypropylene, though. I just put in 40uf caps because I have a box of them. It's easy to parallel up caps, though polypropylenes caps get big. But motor runs are not expensive, and 220uF is certainly a nice kind of value.
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Old 7th February 2013, 12:16 AM   #2477
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Try to add resistances and inductances of wires into your SIM, variable current drawn, and you will see why ground sign have to be drawn near C3 instead of near C1.
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Old 7th February 2013, 01:25 AM   #2478
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Quote:
Originally Posted by Magz View Post
I have the B+, L/R filaments and remote control power all in the same umbilical, with each pair twisted and shielded. Coleman supplies have 1000uF cap at input, B+ is regulated with VR tubes in the preamp chassis, 26s have cascoded CCS plate loads. My filament supply has ~10mV of ripple when it exits the PS chassis. The pre is dead quiet.
Magz very nice build, do you know what the output Z is?
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Old 7th February 2013, 02:20 AM   #2479
Magz is offline Magz  United States
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Magz very nice build, do you know what the output Z is?
The output Z varies based on the volume setting, since I'm using the autoformer volume controls as my output "transformer" as well as a volume control. The autoformer is fed from the mu output of the 26 plate CCS in lossy parafeed, so the output Z at 0dB attenuation will be about 1500ohm, at -6dB about 375ohm, at -12dB about 94ohm, etc. I usually listen with the preamp volume control between -20 to -6dB, so the output z is less than 375ohm almost all of the time.

I've attached a frequency response plot at various volume control settings, from top to bottom -6, -12, -18, -24dB. The input impedance of my soundcard interface is 20kohm.
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File Type: jpg 26 Frequency Response Quick Sweep.jpg (213.6 KB, 283 views)

Last edited by Magz; 7th February 2013 at 02:34 AM.
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Old 7th February 2013, 02:52 AM   #2480
jpak is offline jpak  United States
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Quote:
Originally Posted by Magz View Post
The output Z varies based on the volume setting, since I'm using the autoformer volume controls as my output "transformer" as well as a volume control. The autoformer is fed from the mu output of the 26 plate CCS in lossy parafeed, so the output Z at 0dB attenuation will be about 1500ohm, at -6dB about 375ohm, at -12dB about 94ohm, etc. I usually listen with the preamp volume control between -20 to -6dB, so the output z is less than 375ohm almost all of the time.

I've attached a frequency response plot at various volume control settings, from top to bottom -6, -12, -18, -24dB. The input impedance of my soundcard interface is 20kohm.
Cheers, didn't realize you were using the AVCs on the output. I'll have to read through the last 30 pages of this thread to catch up.
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