User`s manual

Circuit Description B-5
Technical Reference
multiplier may be used. The electron multiplier needs to be biased with as much as -2500VDC to
provide gains as large as 10
7
.
Circuit Boards
There are two main PCBs inside the ECU package.
The top PCB has the CPU, RS232, digital ports, the analog electronics for A/Ds and D/As, and the RF
amplitude detection circuit. A small vertical PCB which holds the log I/V converter connects to the top
PCB. A second small vertical PCB holds the electron multiplier’s HV supply. A third small vertical PCB
is used to pass signals and power between the two main PCBs.
The bottom PCB holds all of the power electronics for the RF, filament heater, ionizer bias, and system
power supplies.
Four PCB’s between the two main boards are used:
1. To connect to the probe.
2. For the I/V converter.
3. To pass signals between the main boards.
4. To supply High Voltage to the CDEM.