Abstract: A digital scene light detecting and integrating circuit is provided with an automatic preset by which the integrating circuit is presignaled to ramp upward to a preselected reference voltage value at which digital pulse counting can immediately begin, thereby subsequently enabling the precise detection and integration of illumination.

Abstract: A DC-to-DC converter charges a capacitor connected to the secondary of a transformer having a primary connected to a low-level power supply through an input control circuit which, when triggered, connects the power supply to the primary for only a predetermined time interval whereby current flows in the primary establishing a magnetic field that stores energy derived from the power supply. When the current in the primary is interrupted, the field collapses, inducing current to flow in the secondary thereby transferring energy from the field to the capacitor. The control circuit is triggered by a voltage sensor that detects the collapse of the field to zero. The voltage sensor includes a sensor inductively coupled to the magnetic field for developing a sensed voltage having a first level during collapse of the field and a second level after the field collapses to zero, the breakpoint between the levels defining the instant at which the field collapses to zero.