The control circuit is under prototype design right now.

 

Our high level design for the control circuit is very simple.  The controller is mechanically separate from the amplifier, so that the amp (and its potentially loud power supply) can be installed at a distance from the operator.  The controller consists of two separate sections, an analog radio/band selection  section, and a microcontroller based monitoring and display section.

 

The radio/band selection section is a simple set of switches that allows the user to override the automatic radio and band selection logic contained in the input/output switching board.  It includes a three position toggle switch to select Left Radio, Right Radio, or automatic.  It also includes two band selection switches (one for each radio), each with six positions.  In automatic mode, the amplifier is controlled by computer inputs to the two DB25 connectors on its back panel.  In manual mode, the toggle switch chooses which radio is active, and the rotary band selection switches choose which band the amplifier should tune to.

 

The microprocessor based monitoring and display section uses a PIC18F4XXX microcontroller to perform two important functions:

 

1) The microprocessor monitors a set of amplifier conditions, and shuts down the amplifier if any of them exceed pre-determined acceptable maximum or minimum levels.

 

2) The processor uses an LCD display to provide the user with status information about the amplifier, including information about any of the monitored conditions that are become and issue and caused a fault.  The processor is not in the loop for PTT or filter control - but it can disable the amplifier by turning off a transistor that is in the PTT switching circuit (and thus disabling the PTT relays).