The Oriel model 68830 power supply was designed to meet the needs of the researcher who demands a highly regulated source of high current for proper operation of light sources. These sources are from tungsten lamps for VIS-NIR radiation or from ceramic glowers for IR radiation. Constant current operation of these sources of radiation is required whenever a radiometric measurement is being made or whenever a highly stable light output is needed. The light sources will be operated in constant current mode by the Oriel Model 68830 power supply with the output voltage being dependent on the load's impedance. A constant current power supply regulates current even into a short circuit, and the model 68830 is such a power supply. It is also safely limited to 2d amperes or 300 watts. Any resistive load which operates between 0-20 amperes and 0-50 volts, and dissipates less than 300 watts may be connected to the 68830 power supply. The Oriel model 68830 does not only provide a controlled source of current to such a wide variety of loads. It also contains circuitry to allow for viewing the output current, the output voltage, and the output power. There is provision for remote monitoring of these output parameters. Remote capability also includes an input for external control, modulation, or photofeedback. The 68830 Radiometric Power Supply was designed to be a reliable and efficient source of direct current The main power supply section usesxiff-line switching technology with the resultant increase in power conversion efficiency, reduction in weight, and wide input mains operation.