I have the earlier 1962 articles where there tat-ii and tat-iii are described. can someone provide a tat-iv schematic, from the march 1969 MR, or at least describe the basic difference between the tat-iii and tat-iv?
Here is some information about the TAT-IV that I found on the Internet. I don’t think the Heath Company is still around. I built many Heathkits in the days of vacuum tube circuits, but I haven’t heard of them for many years now.
http://newsgroups.derkeiler.com/Archive/Rec/rec.models.railroad/2008-05/msg00243.html
Check your PMs
They quit making Heathkits some time in the 1980s. I too built many Heathkits and I miss them, but there are very few do it yourself hobbyists left nowadays. I guess one reason is that electronics have become so sophicated and complex and they can crank out the stuff so cheaply now that it’s not worth building your own. It was fun though. The former Heath Company is now known as Heath-Zenith and deals with things like doorbells, wireless lighting controls and security lighting.
Heath’s ‘successors’ are companies like Elenco Electronics, who still offer many kits, but focus more and more on kits that build toys…
THere’s also the much newer TAT V, which actually uses integrated circuits and you might have a chance of actually building - the older TAT throttles use transistors that in most cases are no longer available, especially the germanium ones. In some cases they had to be hand chosen for the desired leakage, too. Great designs, for sure, but they’ve mostly passed into obselecense these days. If you have a workign one, great, but if you are attempting to build I belive the components of the TAT V are all still avaialble from one or more of th big electronic suppliers.
–Randy