Feel Free to yousendit to [log in to unmask]
On Apr 14, 2013, at 10:34 PM, Dan Nelson <[log in to unmask]> wrote:
> What in the world is this Edison "tuning disc" #3342B21 ?
> It sounds like 800hz tone but they didnt have tone generators back then did they? maybe tuning fork over and over.
> Many thanks for info on what it was for and how it was made