Groner's Low noise measurement amp from Linear Audio vol 3 - spare boards?

[Stefanoo]

Gerber files are here, a little hidden on Groner’s site:
https://www.nanovolt.ch/publications/zip/a_low_noise_laboratory-grade_measurement_preamplifer.zip

You’ll have to purchase Linear Audio Vol.3, available at Amazon, for the required build article.

I thought I read the PCB was two layers board however, looking at the cam files, it seems a 4-layer design.

 

[tombo56]

It is a 4-layer PCB. I’ve ordered PCBs at JLCPCB. Very good quality and low price.

 

[Stefanoo]

thanks Tom for the clarification. I usually use ALLPCBs and find it good quality as well. I used GoldPhoenix in the past, but I think ALLPCBs is slightly better.

 

[Stefanoo]

What is the description of the file stack to distinguish between inner1 and inner2? I don't think it matters much but just to make things equal with all the other implementations out there.

 

[tombo56]

No clarification is available. I left to PCB factory to sort that out.

 

[jackinnj]

In simulation, Mr. Jung's GLED voltage reference would appear to be 3dB less noisy than the 4x 1N4148 reference than Sam used.

 

[jackinnj]

On the other hand, I can't find a current source which is better than the one Sam proposed. Neat trick to use the MMBF5462 to boot-start the CCS.

 

[gentlevoice]

Hi all,

I would like to build this amplifier but before ordering PCBs from JLCPCB I would like to hear if one of you would happen to have a spare PCB that I can buy (preferably from within the EU)?

Cheers & thanks for considering, Jesper

 

[jackinnj]

I had a bunch of boards made up and have plenty. I used Groner's gerber files with no modifications. PM me if interested, will send just for the cost of mailing.

 

[gentlevoice]

Hi @jackinnj : That is a very fine offer, many thanks 😉 ... I will send you a PM later in the day. Cheers, Jesper

 

[jackinnj]

FYI -- I just breadboarded current source and 2V4 voltage reference with through-hole parts -- using Zetex 951 for the PNP's and Zetex 450's for the NPN's. The CCS and 2V4 reference work fine with either J176 or 2N5461 P-Channel JFETs. I could be persuaded to have some boards burned for through-hole.

J175 and 176 are p-channel switches. There are SMT version of both

 

[DNi]

Well, I'd be certainly interested in such a board.
Adding to it an SMD mask for four JFE2140 and the servo could result in an easy to build Groner's LNA V2.