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Old 5th February 2013, 09:44 AM   #1191
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by robertor View Post
hi ramallo.
the diagram I find on page 104 of the thread you recommend, is the correct schema with the TL431 as the voltage regulator?
I'd try to build on proto board and having a transformer with 2 secondary to 18v, build it as a pseudo-mono so I can finally trashing this Chinese PCB.
with 18v the value of the resistors (resistor R21 e pot-trimmer R22) on the TL431 will be the same?
thanks for your patience.
Yes, is correct 1k resistor and 10k pot.

The reason of this board is for do fine tuning the voltage value, the distortion values changes a lot with a small voltage changes.

I don't understand well the use of the two secondaries with this board, can you post a schematic or a photo?.

Cheers
Suso
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Old 5th February 2013, 11:02 AM   #1192
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hi ramallo, thanks for the prompt answer.
sorry, i'm just a hobbyist, i have not studied electronics so my technical terms are incorrect.
The first idea was to use a transformer with a double output 0-18v in such a way as to have two separate PCBs, one for each channel.
but 2 Pcb need double the money to populate them with components.
and this is not the moment.
I think instead I will use a transformer with a secondary 32v and follow the pattern as well as it is drawn.
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Old 5th February 2013, 11:07 AM   #1193
tinitus is offline tinitus  Europe
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Quote:
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...... I will use a transformer with a secondary 32v ....
32V ac would result in about +45Vdc
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Old 5th February 2013, 11:54 AM   #1194
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well, will remain the other transformer of which I can, later, use the other secondary to power a small headphone amplifier.
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Old 5th February 2013, 12:05 PM   #1195
cjkpkg is offline cjkpkg  United States
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I really like the idea of using the TL431 instead of a string of zeners!

I like the adjustability of it.
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Old 5th February 2013, 12:14 PM   #1196
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by robertor View Post
hi ramallo, thanks for the prompt answer.
sorry, i'm just a hobbyist, i have not studied electronics so my technical terms are incorrect.
The first idea was to use a transformer with a double output 0-18v in such a way as to have two separate PCBs, one for each channel.
but 2 Pcb need double the money to populate them with components.
and this is not the moment.
I think instead I will use a transformer with a secondary 32v and follow the pattern as well as it is drawn.
45Vdc is to high, 37Vdc is the max value that a 431 can afford. I suggest you that use just one secondary or connect in parallel both secondaries, or like you wrote in your last message, you can use the unused secondary for other uses such as a headphone amp.

Probably if you had electrolitic capacitors under 50V, you burned all of them (as well the 431)
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Old 5th February 2013, 12:42 PM   #1197
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Suso...............many thanks!
i will try in the next days.
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Old 5th February 2013, 02:28 PM   #1198
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one more question: the IRF610 can be a good substitute of the IRF614?
thanx
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Old 6th February 2013, 01:28 PM   #1199
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by robertor View Post
one more question: the IRF610 can be a good substitute of the IRF614?
thanx
For this use will work
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Old 8th February 2013, 10:42 AM   #1200
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the BoZ gave the first stirrings.
supplied with a switching that comes out to 14.8 v, waiting to fix the power supply recommended.
hums like a hornet but .............. also there is music.
so at first glance it seems to get more down the B1 Buffer, but from the profane i am and after building a power supply as planned, I think the power supply it is very important above all not to do humming.

thanks guys.
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