Sorry for the long rant here, I really didn't mean to go on this long!
N91FA - looks like one of the ones I eventually ended up avoiding - having found some irons with the 4 pin mic connector, then found replacement elements for them, the elements looked to only have the heater wires coming out, which would mean the temp is measured by testing the element resistance - which is pretty sensible, if you think about it. Wish I'd known they contain a thermcouple - would have been ideal - but for the extra cost of needing a transformer.
I actually found some quite nice irons with built in adjustable temperature control - according to the forums I've been reading (the SID project on dangerous prototypes has provided some very useful info) these do contain some kind of sensor. But for the fact I already have the pid controller I would have got one. long!
N91FA - looks like one of the ones I eventually ended up avoiding - h
Re the strange combination of 220v irons with US plugs - these are very common on eBay. Some vendors even throw in an adapter for your country. Some of them have an extra wire with a mini croc clip on, for grounding.
I hadn't noticed the 220v 24v out thing - I'm hoping it's a typo - there looks to be a lot of copying and pasting between the listings for different irons. Not to mention widespread use of Engrish (
**broken link removed** if you need a giggle in that department). I think I may have actually looked at this iron a few times and avoided it for this reason - obviously frustration got the better of me there.
One reason for picking that iron was the wide range of bits available. As far as I can tell it should be fairly easy to modify as well.
Total cost. I got the pid controller last year off eBay for about £8 - I just kept bidding on them until one finished within my price range. They usually go for about £16 I think (oh, here's one like I got:**broken link removed**). Much cheaper than the parts to build my own. The reason I got this pid controller was because I had a cheap 30W iron I got from Wilkinson for under a fiver years ago - similar to this one: **broken link removed** except with a blue handle. They're very common in diy shops and reasonable for the cost (cheap but not nasty). I was going to modify it slightly and fit the theremocouple which came with my cheapo Mastech multimeter using some kind of little collar I was going to make. The plan was to make a box with the pid controller in it, a thermocouple socket bought off eBay (which never arrived, and I moved house in the meantime, so bye bye 99p) and a standard single mains socket to plug the iron into.
So cost was £8 for the controller, £1.31 for the thermocouple, £4.89 for the iron - so £14.20 in total. Any other needed parts I already have.
But then of course, having settled down after the house move, I thought I'd investigate the iron to see if I could get a thermocouple inside the barrel (yes, it is possible), but the element started to fall apart. So at that point I was stuck with the pid controller which for the required temperature can only work with a K type thermocouple, and no iron. It was only after I started digging on the internet and found other homebrew soldering stations which use irons which already have a sensor in them that I started looking at these. Although I could have used a Solomon style iron I didn't think they look comfortable to use. It was only after about 3 days of looking at soldering irons I decided to get a mains iron and stick with my original plan, although I did opt for getting a different thermocouple, since this one has fork terminals fitted and looks pretty sturdy. I'll have to replace the sensor though - I'll try cutting off the casing, but may end up cutting it off altogether and twisting the wires though unless I can weld them somehow. (In a previous thread on the subject someone mentioned dragging the end along a carbon block to do this).
Well anyway I've gone on far too long with this and I'm going to bed