Abstract: A system for sensing metallic debris in fluid flow, including an inductive probe utilizing one or more capacitors with a single turn resonant coil disposed about the flow passageway wherein a second, co-linear, multiple turn coil is provided about the passageway and loosely coupled via mutual inductance to the resonant coil such that the two windings produce a step-up transformer with increased impedance to closely match the impedance of the electrical output cable. This impedance matching reduces output signal loss permitting the sensitive components of the system to be remotely located from the usually hostile environment of the probe. Additionally, a toroid element of low loss, low reluctance material is disposed between the probe and its conductive housing to provide a guiding path for the magnetic "lines of force" of the sensing field produced by the probe, to avoid losses in the housing.

Abstract: A stabilization biasing circuit is provided for an avalanche photodiode. The stabilization biasing circuit allows for a wide range of light levels to be inputted to the avalanche photodiode, while the avalanche photodiode operates under extreme temperatures. The stabilization biasing circuit also provides for an automatic gain control, thereby enabling the electrical output signal of an avalanche photodiode to be relatively constant over a large range of inputted light levels and temperatures. Absence of optical input is identified as an increase in diode noise due to avalanche breakdown.

Abstract: A voltage-controlled oscillator capable of very high ratios of modulation to oscillation frequency is disclosed embodying a resonant circuit with an inductance and two tuning diodes connected with opposite polarity in series across the inductance, a cross-coupled feedback amplifier circuit with two matched MMIC inverting amplifiers capacitively cross-coupled to the resonant circuit for driving the resonant circuit into oscillation at its resonant frequency to produce an output carrier wave, and a transmission line resonator connected to the resonant circuit between the tuning diodes to couple a wide band frequency modulating voltage thereto for modulating the output carrier wave.