Microfunguy
Just to update, a description of how I have the wires attached to the terminal blocks (from the diagram in the first posting here).
The first four left hand terminals are used only, they are marked +, - & Alarm.
Terminal one has 9 volt battery positive & 3 kilo ohm resistor.
Terminal two has 9 volt battery negative, 4.7 volt zener diode anode & USB ground.
Terminal three has the joined 4.7 volt zener diode cathode & the 3 kilo ohm resistor (on a short lead).
Terminal four has the USB positive.
Cheers
Col