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Old 22nd April 2010, 02:44 PM   #1051
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In the application I mentioned I am using a tube rectifier, but the 5U4GB that is directly heated. It does not take much to raise the B+.

With the 5AR4 I see it much less.

D.
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Old 22nd April 2010, 03:13 PM   #1052
Salas is offline Salas  Greece
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Did you make yours yet? After a real application, most of your questions are going to be automatically answered. Its too simple a circuit. I will review your guide resume later and tell if there is some wrong in the guide.
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Old 22nd April 2010, 04:20 PM   #1053
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Not yet, but things are clear (I hope) now.

As I did this infamous work of going through 105 pages of posts, I thought was nice to summarize.

I hope next week I will have the regulator for the DAC working, and then I will test something more ambitious.

Thanks,

Davide
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Old 22nd April 2010, 04:28 PM   #1054
Salas is offline Salas  Greece
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90% of pages in such threads are chronography. I hope you had a good picture of what people can do right wrong or how they feel about the application, ideas, examples, pride, frustration, learning curve etc. Let us know your experience too.

Regards
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Old 2nd May 2010, 04:27 AM   #1055
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Default Lost in Translation

Salas,

Here are three Japanese candidate for a 400 V 100mA shunt. What do you think ?

It's funny how Japanese can be patriotic, they have all their components series. If you ask for a vulgar BC transistor they look at you like you are a loser :-).

Thanks,

D.
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File Type: pdf 2SJ201.pdf (158.5 KB, 45 views)
File Type: pdf A1626.pdf (134.2 KB, 49 views)
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Old 2nd May 2010, 04:38 AM   #1056
Salas is offline Salas  Greece
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The pnp looks nice for a 400V device. Has nice hfe curve that holds for little current and good dissipation. Should work. The Mosfets look much slower, especially the PMOS VS IRF9610. But the NMOS is double the IRF840 Ciss also. Will change the loop gain shape and BW. There is a big stability margin built in the design, they may still work, but its a big risk to make off hand predictions. Will be inferior to the original most likely.

P.S. IRF9620 is good enough if you can't get IRF9610.

P.S.II Their low Rbb BJTs from ROHM, Hitachi, Sanyo, Toshiba, the Jfets, their Sankens, their laterar Mosfets etc. are works of art.
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Old 2nd May 2010, 05:31 AM   #1057
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I was sure that they have great components, but with my limited knowledge is kind of difficult to understand what I can replace with what.

Additionally they like to invert the pins :-)

D.
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Old 2nd May 2010, 05:33 AM   #1058
Salas is offline Salas  Greece
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Do they carry the IRF VMOSFET series in stores there easy to get?
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Old 5th May 2010, 12:01 PM   #1059
housing is offline housing  Hong Kong
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Default My build of Simplistic Mosfet HV Shunt Regs

Hello Salas,

I have completed and tested the build of Simplistic Mosfet HV Shunt Regs using Quanghao's PCB. It looks nice.

The voltage of my build after CRC filtration is about 308 volts. The CCS resistance is 33R and I use IRF610 as the CCS PMOS. I use 135K as the voltage reference after 2SK170 and 60K as the current limiter for the LEDs. Other components are exactly the same as your model build. My desired voltage is about 270 volts for the DAC-end tube stage that consumes about 30mA.

After the regulator is turned on and adjusting the VR, I got about 252 volts that slowly creeps to about 269 volts in an hour's time and settles down within +-0.5 volt. The voltage across the 33R is 1.803 and I assume that it's working perfectly. Am I right?

I also roughly measure the AC output ripple that's less than 0.5 mV using Fluke 189 but it's fluctating very rapidly (I know this is crude). Is the circuit oscillating? Should I use back IRFP9240 as the PMOS?

Thanks in advance for any response.

All the best,
housing
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Old 5th May 2010, 02:04 PM   #1060
regal is offline regal  United States
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Quote:
Originally Posted by housing View Post
Hello Salas,


I also roughly measure the AC output ripple that's less than 0.5 mV using Fluke 189 but it's fluctating very rapidly (I know this is crude). Is the circuit oscillating? Should I use back IRFP9240 as the PMOS?

Thanks in advance for any response.

All the best,
housing
A shunt regulator won't hold a constant voltage (it will drift with the mains.)

Two things you can do without a scope.

1. See if you have this sort of oscillation on your mains.
2. Hold an am radio up to the regulator board and see if you here interferance, if you do there is an oscillation problem.
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