Abstract: A mechanism/device (29) in association with a radiographic cassette (20) in which X-ray film (28) or the like is exposed. Upon exposure, an LED (39) continually blinks, indicating exposure to the user, thereby obviating double exposure of the film. A test and reset circuit (80) informs the user at any time of the operational status of device (29). Device (29) comprises a sensor (30), a photodiode (47), a conduit formed by a bundle (31) of optical fibers which conveys light energy from sensor (30) to photodiode (47) that converts it into an electrical current controlled by an electronic circuit (35) which includes LED (39). Circuit (35) includes a detecting and amplifying circuit (51), an oscillating circuit (68), a latching circuit (65) for maintaining blinking of LED (39), and the test-and-reset circuit (80).

Abstract: A speed detector, for use with a tone wheel having metal teeth, employs two coils positioned in offset relation near the tone wheel for interacting with the tone wheel teeth and thus changing their respective inductances. The coils preferably include iron cores to enhance magnetic coupling. One coil is in a phase sense oscillator circuit and the other is an a tuned sensor network. The oscillator is coupled to, and drives, the tuned network. The change in coil inductances effects a phase shift of the resulting signals in the oscillator and the tuned network, the magnitude of that phase shift typically being double that for a comparable single coil system. The output signals of the oscillator and tuned network provide inputs to a phase condition detector which looks for a reversal in their phase sequence and uses such event to provide timing reference pulses for a final determination of speed in a known manner.

Abstract: An electronic vehicle slow-speed warning system operable automatically to activate the vehicle stop or brake lights if the operator neglects to do so while the vehicle is moving forwardly below a predetermined speed. Both the vehicle backup and stop lights are activated during backward travel at any speed. The warning system is designed for installation in conventional motor vehicles and is constructed entirely of solid state components free of moving parts. The system is selectively operable with either a frequency or optical speed signal sensor and with or without a micro processor.