DIY Nanovoltmeter

For many – one might even say the vast majority – of projects, voltage measurement to the hundredths place is sufficient. For others, you might need more accurate measurements down into the millivolt (.001V) or even the microvolt (.000001V) range, but what about if you want to get down into the nanovolt, i.e. one-billionth of a volt range? It’s a truly small number, which can be affected by a wide range of factors, and building such a device is a non-trivial task.

Non-trivial, but as outlined in Jaromir Sukuba’s build overview, not impossible. In response to the xDevs.com Nanovolt challenge, he designed and built such a device within the contest’s 256 day limit. In fact, he was the only person to complete the build, and for a bit more perspective on its difficulty, there's a discussion about it on the EEVblog.

The new piece of test equipment employs five PCBs for proper isolation, and uses both an FPGA on the largest “Homer” board along with an STM32 processor on the “Marge” PSU board. The three other boards feature Simon-themed names as well, including Bart, Lisa, and Meggie. The outline goes through the design process and choices in some detail, which would be instructive if you want to build on this design.

The requirements of the contest included that the design be open source, so the firmware, hardware, and mechanical components are laid out in the build page. One should be able to build it for around 400 Euros, or roughly 420 US Dollars.