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thoughts on spinners
OSCAR:
Truth be told, the type of optics used on the spinner have a greater influence on backspin than the size/spacing of the encoder wheel teeth. Manipulating the tooth size/spacing is "fix" for reducing backspin, not necessarily the cause.
Mouse optics are notorious for inducing backspin. A dual optic board such as mine and the Happ board effectively eliminate backspin regardless of the size of encoder wheel used with it. Both my optic board and the Happ board may have difficulty reading a small mouse encoder wheel, however.
For example; you can take a standard 24T trackball encoder wheel and use it on a spinner. If you use mouse optics with this encoder wheel, you can get backspin if you set the MAME Speed setting too high. If you use my optic board or the Happ board, it is nearly impossible to get backspin. I have also noticed that some mice optics are more prone to backspin then others.
seaner:
--- Quote from: OSCAR on March 11, 2003, 11:05:20 pm ---Truth be told, the type of optics used on the spinner have a greater influence on backspin than the size/spacing of the encoder wheel teeth. Manipulating the tooth size/spacing is "fix" for reducing backspin, not necessarily the cause.
--- End quote ---
It's the spacing between the optics in relation to the spacing of the gaps, right. phase difference between the two pickups.
I was planning on using the mouse optics, but not in the way they are used in the mouse.. typical mouse optics mount two photodiodes in one package, hence to maintain phase difference, you need to maintain the same gap spacing. I'm planning on using two such packages, and only tap one of the photodiodes in each, and set the spacing as I see fit.
Obviously using the mouse optics straight out of the box is a bad choice if building a custom disc.
OSCAR:
--- Quote from: seaner on March 12, 2003, 01:41:46 am ---
It's the spacing between the optics in relation to the spacing of the gaps, right. phase difference between the two pickups.
I was planning on using the mouse optics, but not in the way they are used in the mouse.. typical mouse optics mount two photodiodes in one package, hence to maintain phase difference, you need to maintain the same gap spacing. I'm planning on using two such packages, and only tap one of the photodiodes in each, and set the spacing as I see fit.
Obviously using the mouse optics straight out of the box is a bad choice if building a custom disc.
--- End quote ---
This is correct. However if you are setting the distance between the phototransistors, then only you will be able to determine the tooth size/spacing which you asked about in your previous post. Not reading the original post closely enough, I assumed you were using a standard mouse optic pair and asking advice on what would be the correct size encoder wheel to use with them. But since you are modifying the spacing between the optics, then it would be difficult for somebody else to tell you the correct size encoder wheel to use with it.
seaner:
--- Quote from: OSCAR on March 12, 2003, 06:58:38 am ---
only you will be able to determine the tooth size/spacing which you asked about in your previous post.
--- End quote ---
That's very true.. perhaps a better question is what seems to be the norm in terms of pulses per revolution on these spinners? This would determine the spacing relative to the size of my wheel.
Cheers,
Sean
djsting:
Seriously guys, why would you want to reinvent the wheel? ??? Save yourself the time and effort and just buy the Oscar Pro from www.oscarcontrols.com it can be purchased with either a PS2 or USB cable making hookup to your PC extremely simple.