This past week I’ve been helping my dad design some replacement boards for the HP/Agilent 3458A multimeter. I don’t know much about what these actually do, but he says that this board is the heart of the 3458A. Apparently it is some sort of DC reference board which uses the LTZ1000. Anyway the protoypes seem to have tuned out great. He thinks he might try to sell his boards on ebay. The cool thing is that we tried hard to keep everything pin compatible so they should work fine in an actual 3458A or standalone in a project like this one.