Digital Tachometer - Presentation testing  - Page 1
Forum section: electronics / general

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: August 07, 2010, 10:48:54 am
content: 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.aspPlus 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 testsI got good readings from 2 meters far ..Enjoy the view ..

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: August 07, 2010, 10:50:04 am
content: Photos continued ...Testing 33+1/3 RPM & 45 RPM

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: August 07, 2010, 12:41:15 pm
content: And a nice video about turntable records ..https://www.youtube.com/watch?v=je1QjRbDu1E&feature=player_embedded#!

author: Neilm
author_rank: Super Contributor
timestamp: October 06, 2010, 06:30:29 pm
content: 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

author: Time
author_rank: Frequent Contributor
timestamp: October 06, 2010, 06:48:02 pm
content: Whats the highest rotational speed it can measure?

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 06, 2010, 06:52:15 pm
content: 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?

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 06, 2010, 06:54:14 pm
content: Quote from: Kiriakos-GR on August 07, 2010, 10:48:54 am

author: Time
author_rank: Frequent Contributor
timestamp: October 06, 2010, 06:57:27 pm
content: it can display that but can it actually measure that?

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 06, 2010, 06:59:46 pm
content: Quote from: shafri on October 06, 2010, 06:52:15 pmWell I can verify with it anything like rotation speed with examples :Power Drill speedComputer fan speedTurntable speedOr 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

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 06, 2010, 07:03:07 pm
content: Quote from: Time on October 06, 2010, 06:57:27 pmI 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

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 06, 2010, 07:13:27 pm
content: Quote from: Kiriakos-GR on October 06, 2010, 06:59:46 pmi 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.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 06, 2010, 07:23:17 pm
content: 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

author: sonicj
author_rank: Frequent Contributor
timestamp: October 07, 2010, 12:45:14 am
content: Quote from: shafri on October 06, 2010, 07:13:27 pmtake 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.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 07, 2010, 06:26:03 am
content: Quote from: sonicj on October 07, 2010, 12:45:14 amyup, 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.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 07, 2010, 07:10:22 am
content: Quote from: shafri on October 07, 2010, 06:26:03 amI had post the pictures !!!! I am innocent