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Old 14th December 2014, 03:02 PM   #1
akis is offline akis  United Kingdom
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Default Driver transistors choice

I am modifying an existing design as follows:

Current system:
Rails : +/- 12V
Complemetary pairs: BC337/MJE15029 and BC327/MJE15028, three pairs in total

New system:
Rails: +/-24V
Output transistors: 2SC6144 and 2SA2222 - also maybe KSE44H11 and KSE45H11 (higher voltages, less fT)

Because of the increased voltages I think the BC327/BC337 are very close to their limits (Vceo=45V) so I need to find a suitable driver for the 2SC6144/2SA2222 or the KSE44H11/KSE45H11

I was thinking the BC639/BC640 or the MJE243G/MJE253G.

If you have any other suggestions?
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Old 14th December 2014, 03:34 PM   #2
AndrewT is offline AndrewT  Scotland
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Driver Transistors

I had to search. I really should find a way to copy these useful links into some kind of reference file.
Any ideas?
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Old 14th December 2014, 06:20 PM   #3
akis is offline akis  United Kingdom
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Thanks that 's useful to have showing the complementary pairs. However since my output transistors are TO-220, for their drivers I was looking more into TO-92 or TO-225 packages.

I was looking at the ZTX653/ZTX753 - have these been used in amps at all?
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Old 14th December 2014, 07:07 PM   #4
Mooly is online now Mooly  United Kingdom
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Quote:
Originally Posted by AndrewT View Post
I had to search. I really should find a way to copy these useful links into some kind of reference file.
Any ideas?
Notepad is easiest and quickest. Just paste in the URL and add a title above it that means something to you. To use just swipe the URL and copy and paste directly into browser top line.

More elegant, use an office type program as I do here. A click on the topic of interest opens the site and page instantly.

You can save anything special (special to you that you want to keep even if the original site disappears) by saving the web page locally on your PC,

http://windows.microsoft.com/en-US/w...page-as-a-file
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Old 14th December 2014, 07:44 PM   #5
alex mm is online now alex mm  Romania
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Andrew, if you satisfied in .pdf format ....
Regards,Alex
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Old 14th December 2014, 08:03 PM   #6
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Common drivers are MJE350/MJE340.
Common LTP/VAS/current mirror/current source are MPSA42/MPSA92
I have designed loads using these and always had good results.
If you start using fast transistors you start to get problems with oscillation.
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Old 14th December 2014, 08:04 PM   #7
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Common drivers are MJE350/MJE340 or MJE15030/MJE15031.
Common LTP/VAS/current mirror/current source are MPSA42/MPSA92
I have designed loads using these and always had good results.
If you start using fast transistors you start to get problems with oscillation.
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Old 14th December 2014, 08:16 PM   #8
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Quote:
Originally Posted by akis View Post
...New system:
Rails: +/-24V
Output transistors: 2SC6144 and 2SA2222 - also maybe KSE44H11 and KSE45H11 (higher voltages, less fT)...I was thinking the BC639/BC640...
2SC6144 and 2SA2222 are also close to their voltage limit. What about BD139/140 as drivers?
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Old 14th December 2014, 09:45 PM   #9
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Quote:
Originally Posted by AndrewT View Post
Driver Transistors

I had to search. I really should find a way to copy these useful links into some kind of reference file.
Any ideas?
Hi AndrewT,

For personal reference material I use MS OneNote. It has tabs, pages and sub-pages. Great for capturing screen shots, text, URLs, imbedded documents and graphics etc. It automatically tags information with the cut location's URL. Its easy to edit, format and organised information. Lots of other features, such as a search facility, info is automatically saved, sync to cloud...

It's also free. I can't understand why its not extremely popular?

regards
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Old 14th December 2014, 10:47 PM   #10
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Quote:
Originally Posted by akis View Post
........I was looking at the ZTX653/ZTX753 - have these been used in amps at all?
NAP90/ NAIT models used this type of combination for some years with up to 30V rails. ZTX652/752 are the actual parts, in combination with high current TO220s, not unlike those you are considering. The actual types were re-labeled with Naim house codes but being a quasi-complementary design, that is irrelevant. Present day replacements for these would be BD911/912 or similar, in that series.

E-line parts rely on the leads for cooling. Despite their max. current ratings, they will run hot when working hard into low impedance loads with such low gain output types. Trying to cool them via the tiny transistor case won't be enough so ensure there are adequate PCB pads and traces or hard wire them with plenty of space for air movement to improve cooling, if your rail voltages are >20V.
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