An adjustable threshold color detector (ATCD) is demonstrated, based on a hydrogenated amorphous silicon (a‐Si:H) and silicon–carbide (a‐SiC:H) p+‐i‐n+‐i‐n+‐i‐p+ multilayer. The ATCD is able to discriminate between blue (λ=450 nm), green (550 nm), and red (≳650 nm) illumination by varying the externally applied voltage within a few volts. The operation of the detector can be explained regarding the ATCD as three independent devices connected in series: a p+‐i‐n+, a n+‐i‐n+, and a n+‐i‐p+. The novel feature is the n+‐i‐n+ cell. It acts as a short circuit under strong illumination, whereas in dark it is equivalent to two low quality back‐to‐back diodes which introduce a shift in the threshold in the photocurrent detection. Thanks to the large number of physical parameters such as layer thickness and band gap the ATCD appears extremely versatile. © 1995 American Institute of Physics.