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WHAT'S YOUR ENGINEERING QUOTIENT?

Problem 1—Your company makes a valve manifold for undersea use containing eight solenoid cartridge valves, each with two #8 studs for terminals. The manifold is typically mounted on a remotely operated vehicle (ROV).

Your task is to design a small PCB that fits over both terminals of a solenoid. The PCB will contain a two pin wafer type connector, suppression components for the inductive transient from the solenoid, and an LED to indicate if the solenoid is energized.

The LED can be observed through the plexiglass cover of the manifold by a monochrome television camera mounted on the ROV. The free space inside the manifold is flooded with hydraulic fluid. The fluid may be either Tellus 32 or a MIL spec fluid. The Tellus 32 is a very pale yellow color fluid. The MIL spec fluid is a deep red.

The LED must be visible through an inch or so of fluid. What color LED should you select for maximum visibility?

ANSWER

Problem 2—What does this circuit do?

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