A simple high current power supply is described. It can be assembled from readily available and relatively cheap components which can be itemized as follows: (1) commercial batteries; (2) fast high current switch; (3) feedback sensor; (4) PC with peripherals for controlling the switch. The apparatus was assembled for heating at very high heating rate with a low resistant load such as a graphite or vitreous carbon tube used as an atomizer in electrothermal atomization-atomic absorption spectroscopy measurements. The high heating rate must, however, be combined with a fairly good control of the temperature of the tube at various levels. This was obtained with a PC and relative peripherals which, directly or through a feedback circuit, control the switch. The system can be easily modified and adapted for other kinds of measurements as long as the high noise of the switching does not interfere with signal recovery. With the atomic spectrometer used (Perkin–Elmer Model 1100B), however, no worsening of the signal noise was observed. The level of current that can be used is mainly determined by the switch since, within a certain range, the voltage and the internal resistance of the power supply can be changed by the type of batteries and the way they are connected. ©1997 American Institute of Physics.