Zero Stability Research Articles

Direct-coupled amplifier for the measurement of small currents

Methods for the reduction of grid current noise and leakage currents in direct-coupled preamplifier circuits are discussed. It is shown that, by combining a cathode follower pream-plifier with a negative feedback output circuit, input grid resistors of very high value can be used. The construction and performance of an amplifier using these principles is described. Features of this circuit are a high zero stability and an adjustable time constant.

Two-phase motor drive using static frequency-doubler amplifiers

A variable-speed drive is described in which a 2-phase induction motor is energized by power modulators of the frequency-doubler type. The system provides continuous and reversible control of motor torque. In comparison with similar drives using conventional magnetic amplifiers this system has the advantages of simplicity, high efficiency, inherent zero stability, and reasonably flat torque-speed characteristics. Both steady-state and transient characteristics of the drive are described and analyzed.

A photoelectric compensator with good zero stability

A laboratory made apparatus for long-time recording of small voltages is described. Care is taken to reduce zero-drift. Some details concerning the construction and adjustment of the equipment are discussed.

A photoelectric compensator with good zero stability

A photoelectric compensator with good zero stability

The Design and Characteristics of a High Sensitivity Direct Current Operated Accelerometer

Some of the more important mechanical design details of a newly developed accelerometer are described, together with their bearing on the dynamic characteristics of the unit. The relationship of acceleration range, sensitivity, and natural frequency for the design is defined, and its properties of selectivity and stability are discussed. Various types of coupling circuits in present use with high and low impedance loads are diagramed, and the possibility of greater zero stability by the use of a low level carrier is noted.

On the construction and operation of a simple form of vacuum electrometer

Details including scale drawings are furnished for the construction of a vacuum electrometer requiring no fine adjustment device other than that afforded by the levelling screws. An outline of the theory is given together with experimental data in illustration, which show that the effect of asymmetry may be varied over an adequate range by means of slight tilting of the instrument. A method of construction is described which with the aid of exterior heat screens minimizes heat convection and thermal and contact e.m.f.'s and so secures satisfactory zero stability. The electrical capacity when used with the vane at fixed potential is made sufficiently low to render unnecessary for most purposes the more complicated method of working with fixed quadrant potentials. Reliability, ease of operation and adjustment, together with good zero stability, are the principal features claimed for this design of the instrument, which, by choosing Wollaston strip of appropriate size, may be made to cover any range of sensitivity required up to the limit set by Brownian motion or mechanical vibration.