Unusual amp from 1987

[minek123]

This is how HexFet quasi may look like.
Simming is not completed yet..

 

[Prohodimez]

Mr. Minek, can I use a pair of 2SK1530 in an MLK QUASI amplifier? The resistor Ratings are unchanged?

 

[minek123]

I don't see why not, but I would recommend re-doing the simulation with models of these transistors. They have lower input capacitance (which is better), than OnSemi hexfets.

 

[stanislav1957]

The LMC has a large loop gain, and it doesn't care about VK distortion. OOS will fix everything.
Лучше с латералами симметричный выхлоп .
With laterals, it is better to use a symmetrical VC.

 

[minek123]

2SK1530 is not lateral. this is vertical mosfet.
Millenium Crescendo amp was using them. Usually, for some strange reason, without drivers, so people may think they are laterals..
See this thread:
Designing amp with 2SJ201/2SK1530


It looks like they need lower current to drive them, that's why no drivers... But they are still vertical.

 

[Prohodimez]

DENON1520AE

 

[Prohodimez]

What do you think of these?

 

[Pano]

Prohodimez you are under moderation approval until you build up a certain post count. You must wait for a moderator to approve your posts. Please wait and do not post the same thing repeatedly.

 

[minek123]

TK30J25D - from that schematic (Denon) looks like they use them just like any other vertical fets.
Should work.
BUT - if you want to experiment - better have spice models for them, and/or good oscilloscope
If you are planning to buy them - why not go for OnSemi hexfets?

 

[Prohodimez]

FQA28N15 is 2 times cheaper. Another question. Is it tedious to install Q3, Q4 on the heatsink?

 

[minek123]

Which schematic are you referring to? From which post?

 

[Prohodimez]

#1021
What are the parameters for selecting LEDs.. Match?

 

[minek123]

That amp (post #1021) hasn't been built or tested yet.
This is going to be my next amp to build.

Check out posts #326, #313 - HexFet quasi Wiederhold77 -
that was already built and tested, and has PCB designed.

 

[minek123]

Schematic from #1021:
1) Q3 doesn't need heatsinking.
2) Q4 - it's running at 350mW, so I guess it will survive without heatsinking, but I would recommend placing it on heatsink anyway.

 

[minek123]

> What are the parameters for selecting LEDs.. Match?

No matching. Just pull them from the bag, and solder to the PCB

 

[Prohodimez]

I made a device like this. It works fine, but I tested about 500 LEDs to get the result.

 

[minek123]

What's the "result"?

 

[stanislav1957]

А что мешает использовать диоды КД522/1N4148 ? Здесь не нужны идеинтичные пары источников образцового напряжения в генераторах тока.
And what prevents the use of diodes KD522/1H4148 ? In current generators, there is no need for ideal pairs of reference voltage sources.

 

[Prohodimez]

Here is another scheme.

Description by LED type.

Working layout. If you do not need to select LEDs in your development, then this is fine.

 

[minek123]

Here are my "final" (?) sims of one complementary HexFet version,
and two versions of Quasi HexFet (with FQA and IRFP260 devices, there are very small differences).
Looks like Maxim's build will be BJT version (triple output), I'm only planning to build HexFet version.
For quasi - not sure yet if I'm gonna use IRFP260 or FQA devices, I guess depends on correct matching.
Have good experience with both of them.