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Old 31st May 2019, 6:26 pm   #31
af024
Octode
 
Join Date: Jan 2003
Location: Ashby-de-la-Zouch (it's not by the sea)
Posts: 1,254
Default Re: Bell and Howell TQII 1652 16mm projector

Thank you for your further comments guys. Was that was some kind of (sine wave?) audible tone recorded into a metal disc off the motor shaft? Wow, I didn't know that. I must confess to being rather sensitive to any kind of variation in pitch. I even graters on me when a record isn't pressed concentrically around its hole! So somehow it seems like I need to press on with a tacho feedback-type solution.

By the way, I was also worried about the 30V peak to peak coming from the tacho, that's why I proposed a potential diver before submitting it to the chip.

I haven't tried to de-pot the original module as yet. I'm quite uneasy about doing so as there's still a niggling doubt (ok, hope) that it might be ok. I guess wouldn't think twice if I had a workable spare. That way we'd all know what was inside the little beggar. I guess I'm going to have to work up to it if I can't with your help, come up with a suitable modern substitute.

Thank you again.

Regards,

Andy
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Now where on earth did I remove that from?
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