Capacitance Decade Box

David built this capacitance array for lab experiments today.

Fiber Optic Link

We've started work on a fiber optic link. The scope trace shows the response of our PIN silicon photodiode receiver circuit (top) to the IR diode transmitter (bottom). This result is with the detector and transmitter in very close proximity. The next step is operation with a fiber cable (we have a 10m patch cable to experiment with).

Variable Power Supply

This weekend, as an additional project, David built the variable power supply shown in the photo. It delivers a continuously variable voltage from 1v to 17v by adjusting the silver potentiometer shaft.

Dive Throttle Arm

This is the throttle arm young David designed and constructed. Note the fine thread on the brass rod that supports the black handle. This was his first time using a tap & die set and he did a exceptional job threading the shafts and tapping the aluminum arm.

PWM Motor Control Board

This is a photo of the control circuit board for the ROV dive motor. The dive motor is located in the center near the bottom of the ROV. It is a conventional pulse width modulation control circuit. The mosfet has substantial copper heat-sink surface area attached. This is required due to the high current drawn by the motors when driving a propeller underwater (average 2.5 amps). The rate at which the ROV descends is controlled by a potentiometer located on the surface control panel. In addition, we have successfully prototyped real-time modulation of the pulse width (hence motor speed) by an Analog Devices accelerometer (with op amp stage to amplify and transition between different circuit supply voltages). This design shows very good sensitivity to acceleration in the vertical axis. It will be incorporated to provide increased stability of the platform for the video cameras and FST or future manipulators.

Depth Pressure Vessel

This is the completed depth pressure vessel. The fitting on the top will connect by tube to a pressure sensor (Honeywell) which has a linear voltage output of 15 mv/psi. At 33 feet, the volume of air will be half the total. We need to build an op amp circuit to drive the signal to the surface to a digital panel meter on the control console.

Video Camera Case

This is the newest underwater case design for our video cameras. I tested this today in 12 inches of water for 30 minutes (in the basement work sink) with no signs leaking. I used 2 inch acrylic tube with matching rubber washers found at the local hardware store. The next step is to build an internal support for the video camera and decide on the best option to seal the external wire feed.

FST

This view shows a nearly complete FST assembly with the plunger release mechanism (aluminum arm) and trigger solenoid (white cylinder on top). We made good progress today fabricating a housing for the trigger solenoid and initial mounting on the FST body.