Jostykit AE500 - Jan Soelberg 250W

[ROVSING]

I just dusted my bookshelf of and found 2 books by Jan Soelberg called AE80, came to read about this AE 500 Amplifier, and then i wondered if anyone have any experience with this ?
I know it's old but at the time it should be a very good and expensive amplifier build on mosfets, with 4 securing circuits build in.(mostly for securing mosfets - they were expensive at the time).
Have any of you guys ever heard this amplifier, and could it be a possible DIY project ? or isn't it worth spending time on ?
Please give me your opinion on this.

[shf1107]

Hello Frandsen.

Very nive finding I suppose. I did search local libraries and the internet several times to find the AE500 amplifier, but could not find the book or any hints on the internet.

Can you possibly scan the diagram and post it here. I would also like to compare with newer designs.

PS! Jostykit is closed and Jan Soelberg is not with us any more, dont think anyone would mind posting here.

Søren

[steenoe]

Can you possibly scan the diagram and post it here.

I am sure that I can help Rovsing with that He just needs to show up with the book Soelberg was quite a genious

Steen

[ROVSING]

I will visit you tomorrow steenoe and bring the book, problem is that the schematic is very "small" in the book, the book also includes BOM, and schematics fore the psu used at the time named NT500 it included 4 trafoes, but there must be an easyer way to make this today.
by the way the Amplifiers right name is AF500 and not AE500 as i wrote in the header.
There is also Smaller amplifier constructions in the book.
Could be fun to make one of this - if its worth spending time on.

[ROVSING]

To Søren

It is actually 2 books named Anvendt Elektronik one of them is a learning book easy to understand about electronics in generel the other book contains Jostykit constructions with good explanations about how it is working.

[shf1107]

Hi Rovsing

I do know the books. In the mid 1980'ies the local library had them, and I did read both books.
But they have disappered from the library now, stolen or scraped maybe?
Therefore I would like to have a look one again.

Yours Søren

[ROVSING]

Hello Søren

Is it only the pages about the AF500 your interested in or is it both books ?
I could send you some copies of those pages, including the pages about the NT 500 PSU if you want it.
Where in southern denmark do you live ?

[shf1107]

Hi again Rovsing

It is mainly the AF500 (and the powersupply) I have been looking fore as I am planning on building a DIY power amplifier.

I am living in Sønderborg. In the weekend, probably sunday, I am going to visit Odense anyway. Maybe we can meet, so there would be no need to pay for posting copies.

You are welcome to email further details.

Yours Søren

[steenoe]

Here is the schematic. If you want the BOM or PSU let me know.

Steen

[ROVSING]

Short about the securing circuits

Output current limiter
2 zeners over gate/source in this case 2 10v zeners and 2 insulationdiodes
limits output current to 20 A

DC fault relays

R33, R35, R34, C16, C19, T2, T3, T4, T6
are the securing circuit it measures continously if the DC comes out of the amplifier fore longer than 0,3 sec. and if - it shuts down the relay in the loudspeaker output, it is also coupled together with T1 on the fet output if idlecurrent is to high it will also shut down.
Actually the relay is shut down by turning on the amplifier, and when everything is in order and the circuits are stabilized and calmed down it will turn on.

Overheating relay

by 80 degrees C pulls one relay and inputsignal will go down with 20 DB or 10 times
100 degrees C pulls second relay and inputsignal will go further 20 DB down or totally 40 DB - 100 times down.
sound will be so weak that it can't damage output no matter how much you turn up volume.

I have translated this from Danish i hope it's understandable current, voltage, bias is not exactly my favorit words, i might have used them on wrong places