When were ECM Compspeed controllers introduced?

Does anybody know when ECM Compspeed controllers were introduced?
There is a thread on rec.models.railroad where Mikes Train House (MTH) are
sueing the DCC suppliers for using back EMF control in their modules. They
claim they patented back-EMF control in 1980.
I moved to the US in the late 1980s and I remember people using Compspeed
Reply to
Christopher A. Lee
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I feel sure they were around in the 80s so if they did they might have a case?
Reply to
fwiw I have a photocopy of a page from elektor date july 77 which has a diagram of a back emf controller so the concept was common knowledge back then , but I think that patents only deal with implementations of ideas , so they may be claiming a particular implementation ie circuit config ...
I did one on my vic20 a long time ago (dont remember the date :-)
I wont rant about the problems of patents , but they do not encourage innovation IMHO and as for the american patent office , it is said they will patent anything ... now where's that application for water :-)
Steve Houseman
Reply to
steve houseman

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