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Old 28th January 2013, 06:46 AM   #11
Bonsai is offline Bonsai  Taiwan
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Bonsai, thank you very much.. i found many articles worth to read in your site.
Power Amplifiers articles is what i'm looking for
Thanks naf!

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Old 29th January 2013, 09:10 AM   #12
naf is offline naf  Indonesia
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Hi Bonsai,
i'm start to read article on your site about Ovation 250 but when i've donwload schematic and read the article everything has changed totally different.
Circuit Description doesn't match with the schematic...

"The input is via J1 and into the non-inverting input transistor pair Q4 and Q7 via a 160KHz LPF filter formed by R28 and C10 ...... "

on schematic Q7 and Q4 is output Transistor.... please would you update and include original schematic so i can learn.

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naf
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Old 29th January 2013, 10:58 AM   #13
Telstar is offline Telstar  Italy
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downloaded! i'll read slowly later, but it looks very good
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Old 29th January 2013, 01:01 PM   #14
Bonsai is offline Bonsai  Taiwan
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Quote:
Originally Posted by naf View Post
Hi Bonsai,
i'm start to read article on your site about Ovation 250 but when i've donwload schematic and read the article everything has changed totally different.
Circuit Description doesn't match with the schematic...

"The input is via J1 and into the non-inverting input transistor pair Q4 and Q7 via a 160KHz LPF filter formed by R28 and C10 ...... "

on schematic Q7 and Q4 is output Transistor.... please would you update and include original schematic so i can learn.

regards,
naf
Hello naf

This is a design from 2006. I posted a new circuit diagram about a year ago. I will update text on th site in the next few weeks. Thanks for letting me know.
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Old 29th January 2013, 01:03 PM   #15
Bonsai is offline Bonsai  Taiwan
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Quote:
Originally Posted by Telstar View Post
downloaded! i'll read slowly later, but it looks very good
Thanks Telstar!
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Old 29th January 2013, 01:12 PM   #16
naf is offline naf  Indonesia
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Originally Posted by Bonsai View Post
Hello naf

This is a design from 2006. I posted a new circuit diagram about a year ago. I will update text on th site in the next few weeks. Thanks for letting me know.
Thanks a lot Bonsai,
even it's your design from 2006... this i new from me and worth reading it to gain my knowledge.
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Old 30th January 2013, 04:11 PM   #17
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Bonsai, is the BC847 (SMD) in thermal contact with one of the Output devices or is it mounted to be in contact with the Heatsink? Due to unavailability of non-inductive power resistors and wanting to couple the nx-amp with a different protection circuit, I would like to make my own PCB (single sided, preferably). Hence, the question about thermal compensation scheme. Thanks.
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Old 30th January 2013, 09:27 PM   #18
Bonsai is offline Bonsai  Taiwan
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Samuel, no it is not in contact with the Heatsinks.

If you wait a few more weeks I will have THP sold screen boards available.
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Old 31st January 2013, 02:21 AM   #19
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Thanks Bonsai. So how is thermal compensation achieved? Thanks for your generosity with the THP Boards offer. I am a little doubtful about being able to source the NXP parts specified in the Protection Circuitry; hence, mine wanting to design my own boards with another protection scheme. However, I'll look at Element14 and RS for the NXP parts.

Another hint to those having trouble sourcing the specified TO126 transistors - 2SA1538 and 2SC3953 would be great replacements.
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Old 31st January 2013, 03:39 AM   #20
Bonsai is offline Bonsai  Taiwan
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Samuel, almost any 100V TO-220 MOSFET with an rDSON of lower than 10m Ohms will work here. I used the NXP ones ... because I get them free ;-)

But of course, if you want to try a different protection scheme then that's fine.
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