- on Microcontrollers
- Published in issue 2/2002 on page 0
High Power Adjustable Load
with power limiter
An adjustable load resistance is indispensable for the realistic testing of power output stages. This circuit provides an electronic alternative to the use of inconvenient high-wattage resistors.The circuit described here has two modes of operation. It can function as an adjustable current sink or as a variable load resistance. At a voltage of between 0 V and a maximum 100 V the sink current can be set in the range 0 A to 20 A. As a load resistance it can be set to values from less than 1 ? to more than 100 k?. The maximum power dissipation is in the region of 100 W. The circuit is designed for operation with DC voltages, but with the addition of a rectifier can also be used with (low frequency) AC voltages. A carefully constructed and calibrated unit can deliver a linearity of better than 0.5 %.