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Silly mistake on a strobe


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Has anyone got one of these.  They are cheap on eBay, but do the job of a disc stabiliser and turntable level really well.  I have discovered, however, that the strobe is inaccurate, just a bit.  I wonder if anyone else has checked theirs. 

 

I have checked this one vs other strobes I have, and this one shows the TT as being a little fast.  I wonder if they made a mistake and made it 33 instead of 33 1/3 rpm or something like that ?

 

s-l500.png

 

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1 minute ago, VanArn said:

For 50Hz and 33.3 rpm , there should be 180rpm stroboscope bars  evenly spaced  around the circumference of the stroboscope.

 

Feel like counting them? :P   Obviously there aren't the correct number, that's why it reads incorrectly under a 50Hz light, but I go cross eyed trying to count those fine lines.

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5 minutes ago, audiofeline said:

Don't bother with the strobe.  Digital tachometers are very cheap on ebay via China.

 

Oh I am not worried.  I bought it mainly as a weight for stabilisation.  Certainly cheap enough.  It just struck me as odd that they get the strobe wrong.  

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1 hour ago, aussievintage said:

 

Oh I am not worried.  I bought it mainly as a weight for stabilisation.  Certainly cheap enough.  It just struck me as odd that they get the strobe wrong.  

When I was at school I studied technical drawing, enjoyed it and was reasonably good at it.  On one visit to the big smoke I went to an expensive art materials shop and bought an expensive technical drawing ruler.  It was really nice, by Linex of Denmark if my memory serves me correctly.  Had a non-slip rubber strip and the scale was held slightly proud of the surface so ink would not run under it.  I took pride in my accurate work, but was confused for months because accurate work on the drawing would be millimeters out when I worked on it later.  I would fix it, then it would be out again.  I think this experience is the reason I'm follicle-challenged now.  One day I thought I would do something silly, and measured the ruler.  The expensive ruler's scale was incorrect.  The changes in my drawing were caused by using the incorrect (expensive) ruler at home and the (cheap and nasty) accurate ones at school.  The teacher didn't believe me, and just thought I did sloppy work.  It taught me a good life lesson - never assume that other people have done their job correctly.

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5 hours ago, VanArn said:

For 50Hz and 33.3 rpm , there should be 180rpm stroboscope bars  evenly spaced  around the circumference of the stroboscope.

There are 180 bars but if you look at it there's a gap between them, caused by where "50 - 33" has been written. So yes, someone has made a pretty stupid mistake.

Edited by Citroen
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I have one of those stabilisers in the OP and also the 'RPM' app on my phone, where you just lay your phone on the platter next to the spindle. The stabiliser indicates the speed is slightly inaccurate but the app says 33.3 rpm. I believe the app!:lol:

Edited by stevoz
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9 hours ago, stevoz said:

I have one of those stabilisers in the OP and also the 'RPM' app on my phone, where you just lay your phone on the platter next to the spindle. The stabiliser indicates the speed is slightly inaccurate but the app says 33.3 rpm. I believe the app!:lol:

Seems they might all be the same.

 

but...RPM app????  Wish I'd heard about this before.  I just grabbed one... wow what an easy way to measure speed.  I was worried about the phone flying off at 78 rpm though :lol:

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