To create high-performance equipment, low-performance components, such as those from the old generations, can also be used. For example, if a conditioning stage (amplification/attenuation or filtering) is made with high-end components having increased performance, the costs are appropriate – using “classical” functional ones, the price of the equipment will become competitive. Low-cost devices may have features that do not make them attractive for inclusion in high-performance equipment but certain errors’ analysis may lead to practical and useful results. A converter circuit from PWM pulses to DC voltage was used. Experimental determinations were made using several types of operational amplifiers and errors analysis and correction was carrying out.