Simple Symetrical Amplifier - Page 42

Lazy Cat · 24th August 2011, 01:12 PM

Quote:

Originally Posted by radio

Hi Lazy Cat (Hi Slovenija)!
I have a few questions about this amplifier.
Is it can replace the bias transistor BC550C with BD139 or some are needed changes?
For the output transistors can be used ate MJ15003/MJ15004?
In the end, I ask you in a few sentences if you are able to explain how this amplifier?
It will be interesting for electronic amateurs!?
thanks and cheers !

Hi there

I will check both Vbe/temperature curve dependency and if OK, than we could use BD139 because of an easier fixation to the main heatsink.

MJ15003/MJ15004 are "strong" enough, have small hFE + gain bandwidth but it would work, though I have never used them in fast CF amp as SSA is.

Lazy Cat · 24th August 2011, 01:30 PM

Quote:

Originally Posted by juma

That's what happens when we have a thread with 100 schematics and neither of them has a clear, distinctive name...

The best we can do now is to refer to them by post number.

It is basically an educational thread so that's the only way to do it. Maybe you've noticed that when it is the post with schematic published, I put always a different SSA name of the post and the yellow exclamation mark.

radio · 24th August 2011, 01:33 PM

Quote:

Originally Posted by Lazy Cat

Hi there

I will check both Vbe/temperature curve dependency and if OK, than we could use BD139 because of an easier fixation to the main heatsink.

MJ15003/MJ15004 are "strong" enough, have small hFE + gain bandwidth but it would work, though I have never used them in fast CF amp as SSA is.

What you propose transistors in TO-3 casse because i have a large refrigerator for this type transistors!
Regards

Lazy Cat · 24th August 2011, 01:43 PM

MJ15003/MJ15004 TO-3 devices are conditionally acceptable, if you have them, you can give them a try, but I suggest to use more modern semiconductors for SSA design, because of its essence comming from the bandwidth.

radio · 01:58 PM

Quote:

Originally Posted by Lazy Cat

MJ15003/MJ15004 TO-3 devices are conditionally acceptable, if you have them, you can give them a try, but I suggest to use more modern semiconductors for SSA design, because of its essence comming from the bandwidth.

I have MJ15024/MJ15025 that are better?
thanks
P.S.
I expect an answer and the other my questions?

AndrewT · 24th August 2011, 02:12 PM

You "expect" or you "hope for some answers".
Which?

MiiB · 24th August 2011, 02:17 PM

some seems to think that this fora is purely for information.....others sees it as sharing and contribution....which i guess is the main intent....

Bigun · 24th August 2011, 05:20 PM

Bigun-AKSA version of SSA: I've started a simulation file to get a feel for how this thing works. I'm not there yet - first incarnation has insufficient gain.

MiiB · 24th August 2011, 05:31 PM

R5-R1 and R10-R6 resistor sets sets the gain....so by increasing R-5 and R 10 you can adjust to the desired gain..

Nico Ras · 24th August 2011, 07:09 PM

Hi All,

I think there are three "tested" schematics here, the L-MOSFET, Michael's (MiiB) BJT version and Andrej's IGBT version.

If I may suggest that Alex would could start a thread where his PCB layout and the associated "tried" schematics are posted for those who want to build and try this superb design for themselves without having to search 400+ posts, but keep that thread totally uncluttered of comments other than PCB layout comments.

Why I am suggesting Alex if he has the time is that he is the only one that has a schematic and BOM that matches up with a PCB on his computer.

Discussions and new ideas remain here on this thread. Any comments on this suggestion?

Regards

Nico

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24th August 2011, 01:43 PM	#414
Lazy Cat diyAudio Member Join Date: Sep 2007	MJ15003/MJ15004 TO-3 devices are conditionally acceptable, if you have them, you can give them a try, but I suggest to use more modern semiconductors for SSA design, because of its essence comming from the bandwidth.

24th August 2011, 02:12 PM	#416
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	You "expect" or you "hope for some answers". Which?

24th August 2011, 02:17 PM	#417
MiiB diyAudio Member Join Date: May 2005 Location: Denmark	some seems to think that this fora is purely for information.....others sees it as sharing and contribution....which i guess is the main intent....

24th August 2011, 05:31 PM	#419
MiiB diyAudio Member Join Date: May 2005 Location: Denmark	R5-R1 and R10-R6 resistor sets sets the gain....so by increasing R-5 and R 10 you can adjust to the desired gain..

24th August 2011, 07:09 PM	#420
Nico Ras diyAudio Member Join Date: Nov 2005 Location: Amanzimtoti - East Coast of South Africa	Hi All, I think there are three "tested" schematics here, the L-MOSFET, Michael's (MiiB) BJT version and Andrej's IGBT version. If I may suggest that Alex would could start a thread where his PCB layout and the associated "tried" schematics are posted for those who want to build and try this superb design for themselves without having to search 400+ posts, but keep that thread totally uncluttered of comments other than PCB layout comments. Why I am suggesting Alex if he has the time is that he is the only one that has a schematic and BOM that matches up with a PCB on his computer. Discussions and new ideas remain here on this thread. Any comments on this suggestion? Regards Nico