SURFACE PRESSURE METER Russian patent published in 1994 - IPC

FIELD: measurement technology. SUBSTANCE: surface pressure meter has Wilhelmini balance, controlling coil, ferromagnetic core connected to holder of balance cup and located inside coil, Wilhelmini plate, system to fix deviations of core from position of equilibrium and system to compensate current in coil. System to fix deviation of core from position of equilibrium is manufactured in the form of capacitor one plate of which is anchored on core and the other one - on end face of coil coupled with inductance coil in oscillatory circuit. System to compensate current in coil has operational amplifier, ammeter, reference frequency generator, unit of phase frequency autotuning and oscillation amplifier. Reference frequency generator is connected to one of inputs of unit of phase frequency autotuning to which other input oscillation amplifier is coupled with output. Oscillatory circuit is linked to outputs of oscillation amplifier. Output of unit of phase frequency autotuning is connected in series with coil through operational amplifier and ammeter. EFFECT: improved precision of measurement of surface pressure and tensions of liquids and films. 3 dwg