Thanks Brett
How do I know if it's AC or DC? for example have a look at these three on eBay...
GDO 2 - looks like AC to me
http://cgi.ebay.com.au/ws/eBayISAPI....m=320485640680
GDO 7 - looks like AC to me
http://cgi.ebay.com.au/ws/eBayISAPI....m=140382313827
Merlin 2600P - not sure??
http://cgi.ebay.com.au/ws/eBayISAPI....m=170444406769
James