This unit provides fusing (2A) and switching of the supply to the instruments. A diode is connected in series with the supply line to protect against polarity reversal of the battery.
The unit provides a regulated 10V supply for the Sound Level Meter (SLM) and for the on board temperature sensor used to indicate Globe Temperature.
It also provides a simple monitoring system for the state of the main battery.
|1||Battery +Ve input|
|2||Globe Temp +Ve|
|3||Globe Temp -Ve|
|4||12v +Ve output|
|6||Battery and 12V -Ve|
Pins 3, 6 and 7 are all connected to Earth in this box.