The reed switch provides an emergency on/off switch that allows divers around
the vehicle to easily deactivate power to the thrusters. The Duke AUV team
uses the RI-80 SMD Series switch. The reed switch works as a magnetic on/off
device. When a magnetic field is placed over the switch, the reed switch flips
to low resistance and allows current to flow. When the magnetic field is taken
away, the switch flips to high resistance and no current is able to flow.
Since the switch can only safely carry 350mA
of current, the switch line does not directly interact with the thruster batteries.
Instead, a 9V battery is connected in series with the reed switch, and the
two open leads are placed across a Crydom relay. When the magnet is placed
over the reed switch, the circuit is completed and 9 Volts drop over the relay.
The 9V activates the relay, which in turn allows the positive +30V thruster
power to reach the terminal blocks on the power board. The reed switch is
podded inside of a 2 pin Subconn Low Profile series connector. The Subconn
cable is mounted underneath the chassis against the bottom acrylic shell.
A horseshoe magnet attached on the outside of the vehicle provides the magnetic
field necessary to trip the reed switch.
Data Acquisition Card
Wireless Ethernet Card
Power Management Board
Doppler Velocity Logger