  It is increasingly suspected that the rare R Coronae Borealis (RCB) stars -
hydrogen-deficient and carbon-rich supergiant stars - are the products of
mergers of CO/He white-dwarf binary systems in the intermediate mass regime
($0.6<M_{Tot}<1.2 M_{\odot}$). Only 77 RCB stars are currently known in our
Galaxy while up to 1000 were expected. It is necessary to find more of these
peculiar and diverse stars to understand their origin and evolutionary path. We
are undertaking such a dedicated search. We plan to follow up spectroscopically
2356 targets of interest that were carefully selected using the all sky 2MASS
and WISE surveys. We have observed nearly 500 of these targets using optical
low-resolution spectrographs. These spectra were compared to synthetic spectra
from a new grid of MARCs hydrogen-deficient atmospheric models. Classical RCB
stars' photospheric temperatures range mostly from 4000 K to about 8500 K, and
therefore their spectra look very different showing the presence of carbon
molecules C$_2$ and CN up to $\sim$6800 K and solely atomic absorption lines
above that. We have put in place a series of criteria to distinguish RCB stars
from other AGB carbon-rich stars. We found 45 new RCB stars, including 30 Cold
($4000<T_{eff}<6800$ K), 14 Warm ($6800<T_{eff}<8500$ K) and one hot RCB
($T_{eff}>15000$ K). Forty of these belong to the Milky Way and five are
located in the Magellanic Clouds. We also confirmed that the long lasting
candidate KDM 5651 is indeed a new Magellanic RCB star, increasing the total
number of Magellanic Cloud RCB stars to 30. We have increased by $\sim$50\% the
total number of RCB stars known, now reaching 147. We also include a list of 14
strong RCB candidates, most certainly observed during a dust obscuration phase.
From the detection efficiency and success rate so far, we estimate that there
should be no more than 500 RCB stars/HdC stars in the Milky Way.
