An illumination activated circuit for supplying power from an oscillatory source to a load. A light sensitive device is arranged in the output circuit of the source such that the signal provided by the source to the load is initiated only when illumination above a certain intensity is received by the device, the device being in effect a dynamic load for the source.

The disclosed oscillator configuration is suitable for being provided in monolithic integrated circuit form and provides a sawtooth output signal having a repetition rate which is controllable and which is substantially independent of temperature variation. The oscillator circuit includes a comparator which senses the voltage across a discrete timing capacitor and switches states to control the charge and discharge of the capacitor. The oscillator configuration insures that no conductive semiconductor devices are connected to the timing capacitor during the relatively long charge time of the capacitor and that all transistors connected to the capacitor during the short discharge time are saturated to minimize the effects of the thermal changes of the active devices on the capacitor charge and discharge times. Moreover, the oscillator circuit requires only two power supply levels and one timing control terminal to facilitate its use in minimum lead integrated circuit packages including other circuits.

Illumination activated transistor relaxation oscillator

Temperature stable relaxation oscillator having controllable output frequency

An oscillator that has a substantially-constant voltage source configured such that it does not require the voltage source to be tuned to a particular voltage to oscillate a particular frequency. The oscillator has greater precision and reliability since the inputs of the comparator are periodically switched to reduce the effects of comparator bias and to equalize the voltage stresses on the inputs of the comparator. Greater precision is also achieved through the use of a discrete resistor and a discrete capacitor to define the frequency of the oscillator. The present invention provides an oscillator and method to generate a periodic signal that is tamperproof because the circuitry that defines the period is either integrated onto the integrated circuit or contained within the package containing the integrated circuit. The oscillator may be used as a frequency reference in a speed governor circuit and that speed governor may be included in an integrated circuit such that the speed governor disables a functional block of the integrated circuit when the clock frequency exceeds a frequency limit.

Oscillator based tamperproof precision timing circuit

The operating condition of a producer of intermittent radiation, such as a motion-picture projector or a television receiver, is monitored by a detector circuit including a photoelectric transducer followed by a filter with a pass band centered on the interruption frequency The detector output is used to control the lighting of a lamp or the drawing of a curtain in a room where ambient illumination is to be suppressed or reduced during operation of the monitored apparatus In one embodiment, the band-pass filter is inserted in a negative-feedback loop which suppresses the frequencies falling within its pass band A band-stop filter may be connected in cascade with the band-pass filter to block the passage of signals due to other radiation such as ambient artificial light

Load-control system responsive to operating condition of producer of intermittent radiation

Accurate and reliable multivibrators are achieved having most of the advantages of on-chip circuits and producing signals with long cycle periods. An off-chip capacitor (1) in an RC timing circuit is charged during the period defined by on-chip capacitor (31) and resistance (33 and 11) RC timing circuit. The cross-coupled circuit has switches (17) and (19) on at least one side, each effective to connect operating potential to respective ones of the two RC circuits. Each has at least two switches (190) and (270) connected in parallel on the other side of the circuit, each operated by respective ones of the two RC circuits of the first side to hold the other side to ground until both RC circuits have operated for preselected periods. Bootstrap voltage from a capacitor (51) is employed to gate the switch FET (45) to the off-chip capacitor (1) strongly on.

Mosfet multivibrator with dual timing

Radiation detection device

Light-inhibiting marine flasher

1,037,525. Transistor multivibrator circuits. M. HORINO. April 30, 1964, No. 17979/64. Heading H3T. [Also in Divisions G1, G4 and H2] A transistor free-running multivibrator circuit has a photo-cell associated with a time constant element of the circuit so that when the light is at a predetermined level the circuit takes up the circuit configuration of a monostable multivibrator and oscillation ceases. In Fig. 3 (not shown), photo-cells E, E 1 are connected one across each cross-coupling capacitor. When one is illuminated oscillation ceases and the corresponding transistor remains conductive. When both are illuminated both transistors become conductive. The collector loads may be relays and one relay may be used to cause a Xenon lamp 1 (Fig. 4, not shown) to flash. When the relay is operated a capacitor 4 charges through relay contact P 1 and contact P2 is open. When the relay is released contact P 1 opens and P 2 closes to produce a trigger pulse at the trigger electrode causing the capacitor to discharge through the lamp.