EEVblog Electronics Community Forum
Products => Other Equipment & Products => Topic started by: Kiriakos-GR on August 07, 2010, 10:48:54 am
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I was in need to measure my power drill rotations per minute ,
so to accurately adjust the speed at the specs of the drill bit that i will go to use.
Started searching and got this one ... many digits ( 99.999 RPM ) and looked well made from outside.
Got it for 10 EUR , and passed all my tests , inner quality + accuracy .
So here it is , my new Digital Tachometer ..
http://www.ce360.cn/Home/ce040_Eng/productshow.asp?id=19&mnid=1039&classname=DIGITAL%20TACHOMETER&uppage=/Home/ce040_Eng/product.asp (http://www.ce360.cn/Home/ce040_Eng/productshow.asp?id=19&mnid=1039&classname=DIGITAL%20TACHOMETER&uppage=/Home/ce040_Eng/product.asp)
Plus my patent , an Velcro collar , with some of the special reflective tape on it ,
so to be totally reusable , and to eliminate the need of buying extra reflective tape in the future.
Test bed , my PLL controlled direct drive Turntable .
The results , more than perfect .
The specific Digital Tachometer XXXXC+ , can measure from 2Cm to 50Cm distance ... in my tests
I got good readings from 2 meters far .. ;D
Enjoy the view ..
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Photos continued ...
Testing 33+1/3 RPM & 45 RPM
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And a nice video about turntable records .. ;)
https://www.youtube.com/watch?v=je1QjRbDu1E&feature=player_embedded#! (https://www.youtube.com/watch?v=je1QjRbDu1E&feature=player_embedded#!)
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I took one look at that and thought wow - I made something similar for my second year project at uni. Wasn't as well packaged though.
Neil
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Whats the highest rotational speed it can measure?
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how does it work? i wonder if this thing can measure accurately across different value of radius. if it detects the linear motion speed, then we have to take into account the DUT radius, isnt it?
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I was in need to measure my power drill rotations per minute ,
so to accurately adjust the speed at the specs of the drill bit that i will go to use.
Started searching and got this one ... many digits ( 99.999 RPM ) and looked well made from outside.
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it can display that but can it actually measure that?
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how does it work?
Well I can verify with it anything like rotation speed with examples :
Power Drill speed
Computer fan speed
Turntable speed
Or the speed of the axle of any motor ..
That's enough for me, as in what I can use it for.
About the how ? check and evaluate the picture of the PCB ;)
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it can display that but can it actually measure that?
I had tested it from 33RPM to 2000RPM , above that I do not know.
But I guess that as long its based on the light , even the ancient synchronization tubes ( pistol shaped light) that was used to adjust the car engines rpm in relation with the spark plugs circuitry ( the translation does not help me here ) we called it as " avans " probably its from France , or another word in English could be as pre-coarse adjustment of the engine .. Any way it should be able to read at list 10.000RPM
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About the how ? check and evaluate the picture of the PCB ;)
i dont have to check the PCB, only the sensor. what i can see is perharps a photoresistor. so it has to be some light emitting or reflective part on one part of the outer rim of the rotating device for the PR to detect. if its the IR/laser LED, then i dont get how its going to sense. the keypoint is the theory behind the design.
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I will stay in the surface saying that the light speed its 300.000 km/ s .
If this item can count the 99.000 reflections at 3 meters per second , its good for the money :D
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About the how ? check and evaluate the picture of the PCB ;)
i dont have to check the PCB, only the sensor. what i can see is perharps a photoresistor. so it has to be some light emitting or reflective part on one part of the outer rim of the rotating device for the PR to detect. if its the IR/laser LED, then i dont get how its going to sense. the keypoint is the theory behind the design.
take a IR emitter + IR collector and aim in parallel. if the object you are trying to measure naturally reflects, put a black dot on it and measure the low pulses. if the object naturally absorbs, place a reflective dot and measure the highs. difference in radius will not affect rpm, only the duration of the pulse.
(http://www.trextuning.com/images/IMG_9929-s.jpg)
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take a IR emitter + IR collector and aim in parallel. if the object you are trying to measure naturally reflects, put a black dot on it and measure the low pulses. if the object naturally absorbs, place a reflective dot and measure the highs. difference in radius will not affect rpm, only the duration of the pulse.
yup, the only problem is i dont see the device in the posted pics. except in the 3rd pic, maybe the cylindrical gold and silver shaped device is the laser emitter (at the top of photoresistor) that could be the way. but Kiri did not mention we have to put a light reflective or absorbant somewhere.
however, the 40 pins Atmel AT89S52 processor seems overkill.
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but Kiri did not mention we have to put a light reflective or absorbant somewhere.
I had post the pictures !!!! I am innocent :D :D