Over the past year and a half since posting the series of pages about the measurement pre-amplifier I’ve designed and built, I’ve received emails from multiple people who were interested in building the pre-amp. I’ve happily shared with them the remaining boards I’ve had from that first batch I ordered at the time. These few boards were all given out, and I’ve therefore ordered a few extra boards to be able to keep offering these boards to people who would like to build such an instrument for themselves. Unlike the first batch, this time I’ve printed boards that fixed the issues I’ve reported when building my own unit and were fixed by a “bodge” over the original board. These modifications to the board design (and the writing of this post) were all done well over a year a go when I’ve originally assembled my unit, but I didn’t see a need to post them until this point in time.
This post is meant to share the updated schematic, as well as to offer additional information that can be of help to people who would like to assemble such an instrument. I didn’t make any functional changes to the pre-amp at this revision, therefore I will offer no additional measurements in this post.