The following modifications will allow the Mighty Ohm Geiger counter board to operate on 5 volts instead of 3 volts.  This modification is required in order to make the serial output of the geiger board compatible with the Arduino Uno.

Modify as follows:

1. Change R6 to 1K ohm
2. Change R11 to 330 Ohms

After making the resistor changes above the next step is wiring the Arduino to the geiger board.

Power & Ground
1. Connect +5v from Arduino to Geiger PCB Pulse J6 pin 1.
2. Connect GND from Arduino to Geiger PCB Pulse J6 pin 3

Serial Data
1. Connect Arduino D5 to Geiger PCB Serial J7 pin 5