There is provided a resonance circuit using piezoelectric vibrator such as a quartz resonator, a coil, a capacitor, or an element equivalent to them in combination. When two resonance circuits having different resonance frequencies are combined, it is possible to configure an oscillation circuit and a filter capable of freely adjusting the frequency characteristic by utilizing the phenomenon that by changing the excitation current or voltage of the respective resonance circuits independently from each other, antiresonance frequency of the entire composite resonance circuit can be changed.

Composite resonance circuit and oscillation circuit using the circuit

Sound generation apparatus to simulate the sounds made by a jet engine. By adding the outputs of two nominally identical oscillators constructed using non-precision components which cause them to have slightly different output frequencies a sound closely simulating whine is obtained. Amplitude of sound is controlled by the use of field effect transistor shunts which have applied to their gates signals representing the parameters which affect the level of sound heard by a listener.

Aircraft sound simulation system

A complex resonant circuit includes: a first current path performing a first gain control to an AC power signal being supplied; at least one second current path performing a second gain control different from the first gain control to the AC power signal; at least two resonant circuits provided on the respective first and second current paths, having mutually different resonance or antiresonance points for the AC power signals passing through the respective first and second current paths and capturing the respective AC power signals; at least one compensation current path performing a compensation phase shift to the AC power signal; a compensation circuit, provided on the compensation current path, for removing an unnecessary component of the resonant circuit; and an analog operational circuit performing analog addition or subtraction on the AC power signal having passed through the first and second current paths, and the compensation current path.

Antiresonant frequency-varying compound resonant circuit

A piezoelectric vibration device includes a single piezoelectric substrate, at least three electrode pairs formed on the single piezoelectric substrate, and two external connection terminal pairs, wherein the three electrode pairs are connected to the two external connection terminal pairs so that two different vibration modes individually appear at the two external connection terminal pairs.

Complex resonance circuit and oscillation circuit using the same

A pulse generating circuit, operative to produce a comparatively low frequency train of pulses or a sine wave for driving an electromechanical timing mechanism, comprises at least two quartz crystal oscillators having comparatively high output frequencies which differ from one another. The differing frequency oscillator outputs are supplied as inputs to a gate which, in turn, produces an output pulse whenever coincident pulses are supplied to its input. A comparatively low frequency signal is accordingly produced at the output of the gate without the need of conventional frequency dividers.

Harold Seidel

Papers

Low frequency oscillator controlled by the difference frequency of two crystals