Abstract: An interval timer circuit (similar to a relaxation oscillator) including a single comparator having first and second inputs thereto and an output therefrom. The circuit includes a first circuit leg having an R-C circuit with a control point therebetween, with said control point being connected to the second input of the comparator. A first reference voltage is established at the first input of the comparator whereby its output changes from a second state to a first state when an increasing or charging voltage at the control point exceeds the first reference voltage. A second circuit leg establishes a second reference voltage at the first input of the comparator in response to the first state at the output thereof. A third circuit leg or discharging circuit produces a decreasing voltage at the control point in response to the first state and when the decreasing voltage at the control point is less than the second reference voltage, the output of the comparator changes to its second state to repeat the process.

Abstract: Within an oscillator circuit of the type wherein positive or negative current is recurrently directed to the gate of a GTO device when the charge voltage levels across first and second capacitors respectively reach trigger levels, voltage sensing circuitry is incorporated to insure that the capacitors are charged during independent periods of time so that the duration of each portion in the frequency cycles is separately controllable.

Abstract: In a relaxation oscillator where the oscillation frequency is proportional to the charge rate of a capacitor, independent current sources are connected through separate switches to change the charge rate of the capacitor and thus the oscillation frequency. Each switch is controlled by signals from a separate detector of a condition which requires that the oscillation frequency be changed. An oscillation frequency increase between the standby and alarm modes of a smoke detector is accomplished in one disclosed embodiment and duty cycle means for controlling the operative period of the alarm indicator during each cycle of the increased oscillator frequency is disclosed in a more particular embodiment.

Abstract: A circuit arrangement for converting an inductance value into a specific frequency particularly for producing a pressure-dependent frequency fully compensated against variations in temperature for injection systems in internal combustion engines. The circuit arrangement comprises a comparator, the output of which is connected to a series circuit comprising at least one diode, a coil with variable inductance and a temperature-dependent resistor, all connected to a current supply line with the end of the coil opposite the comparator output coupled back to a first input of the comparator. The potential of the second input of the comparator can be affected by the output value of a voltage divider between the two current supply lines and a regenerative feedback line emanating from the output of the comparator. During the operation of the circuit arrangement, a pulse sequence is obtained, the frequency of which is determined by the inductance.

Abstract: The VCO is comprised of first and second "nested" oscillating loops. The first loop includes M cascaded inverters interconnected to normally oscillate at a given fixed frequency. The second loop includes N cascaded inverters where the input of the first of the N inverters is connected to the output of one of the M inverters and where the output of the Nth inverter is coupled to the output of a different one of the M inverters, whereby at least one of the M inverters is common to the two loops, and where M and N are integers. A control voltage is coupled to at least one of the N inverters to vary its conductivity and cause the frequency of oscillation of the two loops to change.

Abstract: A pulse generating circuit is provided by charging from a DC power source through charging resistor to a capacitor; detecting the preset value of the charging condition of the capacitor; discharging the charge of the capacitor through a main thyristor by triggering the main thyristor and generating a pulse output to a load by the discharging current. The pulse generating circuit comprises a shunt circuit for dividing the voltage of the DC power source beside the circuit for charging the capacitor whereby the potential of the shunt point is compared with the charged voltage of the capacitor through a three terminal trigger element and the trigger element is turned on when the charged voltage of the capacitor becomes substantially equal to the voltage of the DC power source to obtain the trigger output of the main thyristor.

Abstract: A semiconductor-oscillator comprising a logic circuit having at least one active element, the one input of which is connected by means of a resistor with an inverting output and the same input is connected by a capacitor with a non-inverting output.

Abstract: A fluid level sensor comprising a novel electronic circuit which monitors change in the fluid level in a reservoir through a conductive probe disposed therein. The probe and a capacitor are electrically connected in a circuit which is intermittently energized to create an electrical transient therein. The transient is monitored, and a warning is given when the transient indicates that the probe is not in contact with the fluid in the reservoir. Two embodiments are disclosed as applied to a vehicle hydraulic brake system having a dual reservoir type master brake cylinder with a probe for each reservoir. In one, only a single capacitor is required since the electronic circuit electrically connects each probe with the capacitor sequentially by means of time multiplexing. In the other, a capacitor is required for each probe and the transients in each capacitor/probe circuit are fed to a logic circuit which determines if any of the probes is out of contact with the fluid in the reservoir.

Abstract: An oscillator utilizing a voltage comparator having hysteresis characteristics for producing a pulse train. The width of the pulses in the train is controlled by the charging rate of a capacitor coupled to one input of the comparator and the period of the pulse train is controlled by the discharge rate of this capacitor. The discharge rate and hence the oscillator frequency may be varied in response to a control voltage. Compensating elements ensure that the pulse width is highly stable with respect to temperature variations. The oscillator when in a feedback control circuit, produces oscillations at a frequency whose value is linearly related to the feedback control voltage.

Abstract: A phase control circuit includes an amplifier having a signal combining output, an inverting input signal supplied via a first coupling path with signals to be phase controlled, and a non-inverting input supplied via a second coupling path with such signals, the second coupling path including a reactive element and a variable admittance device. The variable admittance device comprises an operational transconductance amplifier exhibiting a controllable linear transconductance characteristic and an output admittance which varies proportionally to the transconductance in response to applied bias current. Variation of the bias current in a predetermined manner produces a corresponding variation in phase shift imparted to signals provided at the signal combining output.

Abstract: A two-phase pulse signal generator which includes a first triangular signal generator in the form of a closed loop oscillator, a second triangular signal generator for generating a signal which is inverted with respect to the first triangular signal and a couple of comparators for comparing the respective triangular wave signals with a common control signal representative of a control requirement. The two-phase pulse signals are obtained from the respective comparators and the time duration of each of the pulse signals is proportional to the contrl voltage.