Transformer Question

[david_wallis]

I'm just looking at building an opentherm gateway to see if I can talk to my vokera boiler which apparently has an OT interface.

however just looking at the schematic and it has what looks like a 15v transformer, yet shows 24v just before the 7805.. Am I missing something here or can I just buy a 15v Transformer?

Thanks

[raymonvdm]

The gateway is a complete build and after build it is just accepting 230v and uses the onboard transfomer (the blue block) to get 24v to use between the gateway and the thermostat

[hvxl]

I know I have answered this question before... Found it. See this post.