An oscillator circuit wherein two conductivity cells are arranged in a circuit to provide a conductivity ratio which is converted into a linear variation of the period or frequency of the oscillator.

Oscillator circuit for providing a conductivity ratio of sea water

A method and apparatus using a known water-absorbent polymer as a capacitor which is operated at a DC voltage for measuring relative humidity. When formed as a layer between porous electrically-conductive electrodes and operated in an RC oscillator circuit, the oscillator frequency varies inversely with the partial pressure of the moisture to be measured. In a preferred embodiment, the capacitor is formed form Nafion and is operated at a low DC voltage with a resistor as an RC circuit in an RC oscillator. At the low voltage, the leakage current is proper for oscillation over a satisfactory range. The frequency of oscillation varies in an essentially linear fashion with relative humidity which is represented by the moisture being absorbed into the Nafion. The oscillation frequency is detected by a frequency detector.

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Water-absorbing capacitor system for measuring relative humidity

The unbalance of a measuring bridge is measured by means of a frequency variation or period variation of an oscillator. The measuring bridge may, for example, be a four-arm strain-gage bridge. In order to assure a linear conversion of the unbalance, which represents the quantity to be measured, into a frequency or period variation two control loops are required. One loop injects an unbalance compensation current into the bridge via a null balancing system. The variations in the latter system cause a variation of the frequency of an oscillator via, for example, the resistance variation of a photo-sensitive resistor. The second loop ensures that a second equivalent impedance in the frequencydetermining network influences the oscillator in the same way, so that the square root of the two impedances yields the linear relationship. The invention indicates how by the choice of the oscillator the control loops can be simplified, for example, by using multiplier circuits as variable potentiometers, and how in a simple manner either a frequency variation or a period variation can be obtained as a measuring result.

Circuit arrangement for converting a bridge unbalance into a frequency variation

Ignition pulses are supplied to an internal combustion engine from a breakerless electronic ignition system wherein the ignition pulses are produced in response to the movement of teeth on an electrically conductive trigger wheel past an inductive sensor. The inductive sensor is part of a LC tank circuit of an oscillator normally producing an oscillatory output signal which is detected by a bistable demodulator, and as a tooth moves into close proximity with the inductive sensor energy from the tank circuit is lost through an inductive coupling with the trigger wheel until the oscillatory output signal is terminated. The bistable demodulator responds to the absence of an oscillatory output signal by producing a timing signal which causes an ignition pulse to be supplied to the engine. The trigger wheel rotates in synchronization with the engine, and the initial timing of the ignition system is determined by setting the relative positions of the sensor and the trigger wheel. To advance or retard the initial timing of the ignition system, a resistor is connected across the tank circuit by a controllable switch to control the energy level in the tank circuit and hence the time required to terminate the oscillatory output signal. The initial timing of the ignition system may be set with the resistor electrically connected across the tank circuit, and upon the occurrence of engine conditions may result in undesirable ignition knock the controllable switch may be rendered nonconductive so as to retard the timing of the ignition pulses. Alternatively, the initial timing of the ignition system may be set with the resistor electrically connected across the tank circuit so that under certain engine operating conditions the switch may be rendered conductive to advance the initial timing of the ignition system. The switch connecting the resistor across the tank circuit may be a transistor which is rendered fully conductive or nonconductive by control signals produced according to predetermined engine operating conditions, or alternatively the conduction of the transistor may be gradually varied from fully conductive to nonconductive so as to serve as a variable resistor gradually increasing or decreasing the resistance across the tank circuit and thereby gradually advancing or retarding the initial timing of the ignition system.

Breakerless electronic ignition system

A circuit which is responsive to sixty cycle voltage coupled to the circuit by a human body from a proximate 60 cycle power line. An input terminal when touched by a person's finger has coupled into it a 60 cycle voltage which is amplified and causes the electronic circuitry to assume either a conducting or non-conducting state at its output which is maintained after removal of the finger from the terminal. The output of the circuit is connected to a controlled device which is controlled by the circuit output state.

Horwitz Joshua

Papers

Oscillator frequency control