The paper presents a new calibration algorithm for current output R-2R ladders. The R-2R ladders are popular because they are easy to realise, but the resistance tolerances limit their linearity properties. However, it is possible to achieve higher linearity with self-calibration techniques. A formerly published algorithm by Cutkosky is available for the so-called Cutkosky R-2R ladders. A similar algorithm can be applied to the current-output ladders, which are widely used as MDAC or DAC. In the paper the Cutkosky divider is shortly discussed, and then a new description is presented as basis of the calibration algorithm. The calibration algorithm is discussed in details, and the error budget is analysed. A simulator was also written to verify the theory.

High precision, high Q-factor and small phase shift of output with input voltages in the case of an angular frequency change within broad limits is described in the paper. New tuned amplifier is grounded on the self-adapting principle of operation. Dynamics analysis of a double loop, non-linear modulating system is grounded on the usage of the generalized method of linearization by the describing function.

The use of instrument transformers in virtual electronic instruments poses certain problems. This paper points to some of these problems and the possible ways of dealing with them. Specific examples dealing with improvements made to the standardtype inductive measurement transformers, as well as some unconventional models of instrument transformers are presented.

To maintain the group of standards it is necessary to periodically compare the members of the group with each other and to obtain a measure of the deviation of the values of the members from the mean of the group. The mean of the group can be calculated by using a set of equations. In the national metrology institute of Turkey this work is carried out to reduce the time for calculation for the resistance measurements. The measurements are done automatically and the results are evaluated by using the computer program. By using this program, compared resistance values, history of the resistors and graph of each resistor are obtained very easily. This program can be adapted to the other group of standards i.e. mass standards, voltage standard cells, capacitance standards.

The following paper is a presentation of the digital system used for measuring interference in low frequency range that occurs in low-voltage power supply. It discusses how the hardware of the system, controlled by graphical programming environment LabVIEW v.4.0 National Instrument, has been realised. Furthermore, it presents basic functions, which the virtual part of the system performs. The paper gives special attention to the methods used in determining quantities, which describe deterministic as well as stochastic types of interference. Additionally, the paper defines the conditions deciding about inaccuracies of the evaluation of estimators.