Abstract: A position control circuit having a demodulator with automatic tuning capability for use in an electro-hydraulic positioning system used to position a servo device. The position control circuit includes the demodulator, an analog to digital converter with an input voltage range, and a microcontroller. The demodulator has a gain and is operable to convert a feedback signal from the servo device to a position signal having a lower voltage value when the servo device is at its 0% position and an upper voltage value when the servo device is at its 100% position; the lower voltage value and upper voltage values being a function of the demodulator gain.

Abstract: A peak amplitude detector for use in a synchronized position demodulator associated with a linear variable differential transformer. The peak amplitude detector adjusts for phase shift in the transformer and maintains the full bandwidth of the transformer. The detector obtains the maximum positive or negative amplitude of the sinusoidal signal at one of the secondary windings of the transformer by first counting either a positive or negative half cycle of the signal and then while down counting one half of the counted half cycle sampling the amplitude of the sinusoidal signal. The sampling ends when the count reaches zero.