  Recently there has been an increased interest to apply the sensitive
$\beta$-decay anisotropy detected nuclear magnetic resonance ($\beta$-NMR)
technique to biological studies. A low-field (non-super conducting magnet)
liquid $\beta$-NMR setup was build at ISOLDE to allow such investigations and
to use the resolution gain of liquid-state NMR in nuclear physics. As part of
this setup a magnetic field locking system, a set of printed circuit board
shimming coils, a sample exchange system, a set of compact $\beta$-detectors
and a custom experimental vacuum chamber were developed. The main magnetic
field was stabilized down to the ppm level by the locking system while allowing
the direct determination of the absolute magnetic field. The homogeneity of the
magnetic field was improved to $\leq$ 5 ppm over the sample volume by the
shimming coils. Sample changing times were reduced from hours to mere minutes
by the liquid sample exchange system and during experiments it was possible to
continuously observe the sample from an accurate reproducible position because
of the custom chamber and compact $\beta$-detectors. With these upgrades
low-field $\beta$-NMR experiments can be, and have been performed. The absolute
field determination allows for a novel way to reference $\beta$-NMR
measurements, abolishing the need for time consuming reference measurements.
Possible future applications include the study of the distribution of nuclear
magnetization and (bio)chemical studies.
