Laney TF300 footswitch

[Gargaman]

Hello, folks.
Got a new amp (used).
Need a footswitch, maybe I'll try and make one myself.
Some doubts:
- What is 'G"?
- Can I.use battery (cells) to provide the 5 volts?
- In case I fail, will ruin the amp?
- Can you see the schematic clearly?

Thanks.

[Slowpoke101]

Check the picture below. It's actually quite simple.

[Gargaman]

 
I suppose that the 'real' ground (pins 2, 6 e 9) is also provided by the amp.
Thanks, mate!