Thanks for all the replies. I'm not building a temperature controlled soldering station
The heater I am using is an 18W heat mat, designed for reptiles. I am using it to heat a small enclosure that (fortunately) doesn't contain reptiles. Instead of buying the expensive heat controller, I thought I would look into how to build one. In future I might build a larger enclosure with a larger heater, the biggest is around 60W.
I have found a diagram of what Diver300 recommends here:
Power Supplies
Diver300's post and that diagram explains it very nicely. I have built 7805 supplies before for DC-DC so am quite happy with that. However I have two further questions if anybody can help:
1) The transformer specification sheet shows 4 connections on the 'stepped down' side, 0 SEC 0 SEC. Which are connected to the bridge rectifier? Why are there two 0 connections?
2) I am assuming that a 50V 1 or 2A bridge rectifier will do, something like
**broken link removed** ? I am unsure here though. I assume 50V because that's the minimum and I'll be using a 12V transformer to step down. Power requirements are quite low and the 7805 only does 1A from memory.