Using a HB-25 Motor Controller and a BS2e to control a turntable?

jay117

hello,

This is my first post here. I am work on automating my recording lathe, its from the '40s so all the mechanical aspects are there..

I am currently looking into the HB-25 Motor Controller to control a 1,800 rpm 1/4HP motor. The platter is 17", and I have a 0.740" pulley for a belt drive configuration.

@ 1800rpm a pulley of 0.740" would give me a platter speed of 78.35rpm, I would like to slow down the motor to 78.26rpm, 45rpm, or 33.33rpm for the speed that was selected.

would the HB-25 Motor Controller alone work, or would the addition of a Position Controller Kit be a good idea?

My main concern about a Position Controller Kit is that it seems to need a distance to travel, and I need the unit to set the speed and go when the start button is pressed, and to stop once the stop button is pressed.

Since the unit is for the mastering of vinyl records, I also need to make sure the speed is rock solid, with no wow and flutter. Am I on the correct path?

$WMc%

The HB-25 should work fine assuming:
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The motor is DC
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No more than 24volts MAX (And this is a little out of spec for HB-25 )
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The motor doesn't draw more than 25 amps
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Your gonna need a speed encoder of some kind. An Optical chopper placed on the motor would work well.( This is just a disk with evenly spaced notches or holes to make and break a light signal)
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Your gonna need to write a PID program in the Stamp to INPUT the speed you wont, Drive the HB-25, Read-in the Optical chopper, Then adjust the HB-25 to match the speed you wont.
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The Stamps work pretty fast and they should have the RPMs perfect in the short intro time before the recording starts on a vinyl record, And keep the RPM constant through the hole recording.(This depends on how well you wrote your PID controller code)
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Finally, I would record the whole recording to digital and then edit it in some digital software.
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Google PID control........(this will help you understand how a PID controller works)
Google BS2 PID code...(this will help you write some code)
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Hope this helps you to get started. This is not a real hard project to do at all. You'll be surprised at how well you can control the motor RPMs.
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If you have more questions or you get stuck, Thats what the Forums are for.
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P.S. Welcome to the Parallax Forums

jay117

Thanks for the welcome and the info.. The method you describe sounds a lot like the position detection kit. I wonder if I can just use a hall effect sensor, or something similar.

EDIT:

Found a great post about PID and Stamps: http://forums.parallax.com/showthread.php?77656-PID-Control-Intro-with-the-BASIC-Stamp

$WMc%

Yes you could use a hall-effect sensor. Just remember to keep the flying magnets far away from the vinyl record.
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Take a look at this
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http://www.parallax.com/Store/Sensors/PressureFlexRPM/tabid/177/CategoryID/52/List/0/SortField/0/Level/a/ProductID/90/Default.aspx
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Its the Melexis 90217 Hall-Effect sensor. I used this a lot to measure RPM (counting) and proximity. It works great and is easy to use.
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Radio Shack carries some small 1/8" magnets R.S.part# 64-1895, This is a 2 pack. I would use at least 4 magnets but 8 magnets would be better.
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I'm not familiar with the Position Kit. This might be an easy retro-fit for your project?
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Cool link to a BS2 PID post. This post explains PID in a nut shell, Way better than I could have explained it.

Iguanaman

Need simple software to control HB-25 for propeller 40 pin chip. any help would be nice. Thank you. 30 oct 2018(tue)

Publison

Iguanaman wrote: »

Need simple software to control HB-25 for propeller 40 pin chip. any help would be nice. Thank you. 30 oct 2018(tue)

Welcome to the forums. You should ask this in the Propeller 1 forums.

tomcrawford

OBEX has 1 entry for "HB-25". Searching the forum gets lots of hits for HB-25, both spin and C.