Forssell Opto Compressor

[Svart]

I vote for both IC and transformer pads/holes on the PCB. why limit one's choices?

 

[tk@halmi]

[quote author="Svart"]for FET opamps are we talking about a tl082/92 or something like the opa604/opa134?[/quote]

More like the OPA604. That opamp is hard to beat when you run it off +-24V rails.

It is becoming increasingly more difficult to make JFET input DOAs because high gain & high voltage devices are quickly disappearing.
I have been working on one for a few months based on the 2N5566.

 

[Svart]

so when are we going to see some prototype testing/numbers guys?

 

[hitchhiker]

I'd like to see the Quad8 work here, but I don't know what their input
impedence can be set at.

Lance

 

[soundguy]

seems like lots of people have made the melcor amp and have api transformers, thats probably what I woudl lean towards, melcor opamps and a 2503, have a nice api flavored optical limiter.

dave

 

[FredForssell]

If anyone is interested in using a JFET-992/993 type discrete opamp as a gain make-up/buffer amp in your opto project, here is a PDF containing a schematic for a dual channel board. This board has servo amp for DC offset control, and + and - 24 VDC regulated power supplies.

The schematic is at http://forsselltech.com/schematics/Dual%20Amp%20PCB%20Schematic.pdf

A zipped file containing the schematic, PCB top and bottom layer printouts, and all gerber files is available at http://forsselltech.com/Dual%20Amp%20PCB.ZIP

Edit: Dot gone!

 

[rafafredd]

Great!

The link you posted is not working. You shoul delete the last dot "." for it to work right!

Thanks a lot for the schems and Layout!

 

[Svart]

anybody get a prototype working? it's like waiting for a new baby.. :shock:

 

[Bryson]

[quote author="rafafredd"]Great!

The link you posted is not working. You shoul delete the last dot "." for it to work right!

[/quote]

He gets an 'A' for punctuation though.

 

[hitchhiker]

Could ch 2 connect directly to the first side chain for a simple stereo comp?

Lance

 

[Svart]

this thread better not die! I really like the idea of this. anyone try it all out yet?

 

[Bauman]

I'm considering to include this boards on next batch I'll fab. Anyone did a check as Fred suggested??

 

[rafafredd]

Fabio,

don´t fabricate the boards based on the Forssell PDF files. Look at that:

There are tracks that are almost touching and if you look carefully, there are actually some shorts in there.

I don´t know the method he used to output the PDF files, but it did not work as it should. Maybe you can get the original gerbers with him.

 

[Bauman]

Rafael, ok.
I just need the gerbers to fab
I got some nasty pdf generated the other night... very strange sometimes...

I'll check those board.

cheers!
Fabio

 

[rafafredd]

Fabio is your ab_designer.... email box working? I´ve sent an email about boards fab yesterday. Did you got it?

 

[StephenGiles]

Has this died a death?

 

[StephenGiles]

Hi Kubi - I expect you are right! Are you having this crazy summer waether over there in Germany? I am 20 Km south of London, and today it is very humid, 24C and hot when the sun comes out, but we have had some rain and thunder too!
Stephen

 

[StephenGiles]

I agree. We just spoke to some neighbours who were in Sorrento near Naples last week, and the temperature hit 41C!
Stephen

 

[FredForssell]

If it has died, I hope it's not becasue of the pdf printout. The gerber files are fine.

 

[TomWaterman]

Hi!

I hope this hasn't died, it has been very interesting so far.

Would there be a way to a include a sidechain link so that two units could be used for stereo?? I would like to build two mono units for tracking but I bet they would also work well on stereo busses and such....

Cheers Tom