A wavelength‐scan and intensity‐control system for a widely‐used, high‐intensity monochromator is described. The wavelength scan is bidirectional and variable speed, and may be controlled manually or by TTL logic from a computer. The intensity control is effected by use of a programmable dc power supply and D–A converter. Various filters are described which allow an intensity of up to 2×1014photons/cm2s to be achieved in a 1 cm×3 cm area over a wavelength range 0.76–2.50 &mgr;m, at 0.07 &mgr;m bandwidth, with a single grating. (A lesser intensity is available to 3.4 &mgr;m.) This wide range is made possible by the use of second‐order light from 0.76–1.00 &mgr;m. Photoconductivity data in GaAs:Cr and InP:Fe are presented, as an example.