audio qualia 2

Blog

rotary encoder

Posted by cat's squirrel on August 9, 2012 at 11:00 AM

 

I've just received my rotary encoder from Hong Kong, it will be used to measure the rotational speed of my Lenco turntables, by connecting to the spindle with a Michell clamp and CNC coupler.

 

Readout will be from a 5 digit rev counter. The problem is, all the necessary info is in Chinese, but I'm sure I can work it out.

 

Here's a pic:

[img]http://img52.imageshack.us/img52/5089/p1014841rotaryencoder.jpg[/img]

 

Inside the encoder is a disc with 1000 slots in it. For each revolution of the turntable platter, it outputs 1000 pulses, which are counted with a rev counter, so 33.333 revolutions/minute should produce 33,333 pulses on the rev counter.


I have  received the tachometer, and hooked it up to the encoder. First look gave a result of 33457, not bad at all. I just need to fit a load resistor, and construct an arm to steady the encoder.


Had a problem with the setup, it would work for about 30 seconds, then the readout would blink. Eventually, I realised that the battery I was using as a power supply was dipping to too low a voltage. Replacing it with a wall transformer (12v 1.2A) kept everything working perfectly. Should be working by the end of the week.


Categories: None

Post a Comment

Oops!

Oops, you forgot something.

Oops!

The words you entered did not match the given text. Please try again.

Already a member? Sign In

2 Comments

Reply David
6:28 AM on August 27, 2014 
It has been a while since I looked in here.... so excuse the late posting...

How did you go with the encoder?

There was a thread on Audiokarma in which Luckydog demonstrated a polar plot method for representing speed stability based on a 3kHz test track...

He synced 360degrees of the polar chart to 1 rev of the platter.... which provided an interesting view of platter/record centering as well as speed stability - you might want to track down that thread.

It also demonstrated the effect of stylus scrubbing / arm low frequency damping on speed stability.

Might be relevant to this particular speed stabilty posting

bye for now

David
Reply cat's squirrel
11:12 AM on August 28, 2014 
David says...
It has been a while since I looked in here.... so excuse the late posting...

How did you go with the encoder?

There was a thread on Audiokarma in which Luckydog demonstrated a polar plot method for representing speed stability based on a 3kHz test track...

He synced 360degrees of the polar chart to 1 rev of the platter.... which provided an interesting view of platter/record centering as well as speed stability - you might want to track down that thread.

It also demonstrated the effect of stylus scrubbing / arm low frequency damping on speed stability.

Might be relevant to this particular speed stabilty posting

bye for now

David


Hi David

the rotary encoder principle did work, and gave a very acceptable readout. The only problem, which was a slight one) was the centring of the interface (Michell clamp and CNC connector). The latter is always a little out of true centre by the nature of its construction. So I have bought another encoder with only 100 segments, and will interface this with the outside of the platter with recording tape. Only thing to make is the 1/10th sized pulley which, hopefully will get me back to the 1000 pulses per revolution of the first one. Then I can use it on any Lenco, while it is running, and no need to take it off after every record!

Why don't you join us here: www.http://audioqualia.prophpbb.com

Kindest regards

Bryan