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Forum Index : Microcontroller and PC projects : Turntable speed control
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 6779 |
Yep, that's the sort of stuff. Almost impossible to fit to most ready-built turntables There are exceptions at the top end). I have considered a feedback system for this project. A black stripe under the platter would give me one pulse per rev. I could get the speed and shift the motor frequency slightly. There's not much point in sampling more often than that as this is a flywheel system - it takes time to respond. Even correcting after every rev might be too frequent. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Yeah it's a big ol' flywheel. Those guys still sample @500Hz though. I was thinking a SETTICK 1 on the Pico and an encoder resolution to suit. Craig |
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lew247 Guru Joined: 23/12/2015 Location: United KingdomPosts: 1702 |
Jim do you have any details on this? I'm going to need a ctcss encoder/decoder for a project I have in mind (radio interface) If you had anything to give me a head start it would be great |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6097 |
Nothing to detail I needed 91.5 Hz continuous so PLAY TONE 91.5 A standard audio filter and the level reduced to what I needed. I was no doing a decoder. I would use a dedicated IC for that. Jim VK7JH MMedit MMBasic Help |
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| zeitfest Guru Joined: 31/07/2019 Location: AustraliaPosts: 482 |
Just an observation  A certain product of "Danish shortbread biscuits" is packaged in a circular tin, at a premium cost, with two layers of admittedly delicious biscuits. I would guess they are a global merch in supermarkets etc. The lid has a circular pattern of alternating small strips near the outside. Counting them gives 384 ... which is 256 + 128 ie 1 and a half 256. My thought is, that should be useable as an optical counter and so give direct digital velocity/positioning. Maybe even photo-reduced to a smaller size. [There is also another such pattern on the side of the tin but that will have a join in it so maybe not as accurate for a circle, but maybe unrolled for a linear application? ] I haven't tried it though. |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4222 |
Pico can do it. It can decode morse (not as good as a human, but it works), so it can also decode this tone.. Volhout PicomiteVGA PETSCII ROBOTS |
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phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2135 |
https://www.qsl.net/g4usp/Simple%20CTCSS%20CODEC/CTCSS%20CODEC.htm Using a NE567N |
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