Low Cost Encoders
 

Recently a number of encoders have popped up on ebay like this and this with excellent prices (<15$)! Considering the cost of some name brand rotary encoders they look like a excellent option for applications that do not require perfectly calibrated sensors. They are also available for purchase in small quantities unlike a number of other encoders. Does anyone have any experience with them?

Re: Low Cost Encoders
 

Not yet but I soon will :confused:.
I will let you know when they arrive.

Re: Low Cost Encoders
 

Great, I would grab a few for myself to review but It will be a while until I get purchasing access. Most of the items I order from china take about 2-3 weeks to arrive.

Re: Low Cost Encoders
 

Got the encoders today.

5 wires each
A & B
Vcc / System ground
Shield ground

Color code in Mandarin Chinese.
Actually not a problem.
http://mandarin.about.com/od/vocabulary/a/colors.htm

Black = system ground
Red = Vcc
Shield ground is black higher gauge or bare
White, Yellow, Green are A & B

Will power them up tomorrow.
These are likely too big for AndyMark gear boxes without shaft couplers and spacers.

Re: Low Cost Encoders
 

I would rather pay little more and buy from someone who has designed and made the encoders (or anything or from any country for that matter) as long as they own the intellectual properties for the product. It's unfortunate that many companies steal designs or copy products from others and make quick buck.:mad:

Re: Low Cost Encoders
 

No offense but optical encoders have been around for decades.

As much as I too would like to take the 'high road' here:

First let us start with a basic question: who invented the first shaft encoder?
You are tossing around the suggestion that they stole it.
So let us demonstrate from whom.
Consider this a lesson for the students.
Hint: Look up Murray Hill, NJ....Dr. John Northrup Shive....Bell Telephone Laboratories.

I take some issue with the use of non-American parts to operate U.S. FIRST as well.

Then again ask National Instrument to catalog where their parts and assembly come from.
The $2,000+ 8 slot cRIO myself and another mentor bought was shipped to us from Turkey.
That doesn't sound like 'Made in America' to me.

So why is it okay to use labor unknown from one country but not another?
Can you prove that abuses of labor are any less in one place than the other?
Have you personally checked?

Keep in mind when I bid on the 2015 control system I was going to do *all* the assembly in the United States.
I flatly stated in writing that the additional cost was irrelevant to the potential quality control issues.
Never mind the potential language barrier (my Chinese is laughable).
I did not suggest these other countries were thieves without evidence.
Here's your chance show your evidence.

I note that in the topic about the RoboRio you never asked where that product came from but did admire the cost savings.

Further *who am I* to decide that teams with deep pockets are more entitled to working encoders than teams just managing to show up? Why should those with less in their purse not buy parts probably made by those with less in their purse?

Now I have encoders to test you seem relatively new here you might want to take note:
Of all the people you could try to insert your politics with >I am the last person on Earth< to do it with.
If I think your case is questionable I will poke holes in it.
It is not personal nor is it about whom you are with politically or otherwise.
It is merely my scientific method which is quite incompatible with politics.
Do not assume that as a member of Team 11 they control me either or that I speak for them.
I am me and my choices are my own.

Sorry if that's a little rough but when you end on an angry emoticon you should recognize the types of response you might get back.

Re: Low Cost Encoders
 

Have not forgotten about this.
Dealing with a Linux bug that has some urgency.
Will have an answer before Sunday.

The A&B outputs appear to be open-collector.
So I will set these up and turn them with a motor then sample the output quality and provide it.

I will also work up a circuit to divide the output down to encoder resolutions more common to FIRST.

Re: Low Cost Encoders
 

These look a lot like the encoders made by 1114's sponsor Industrial Encoder Corporation.
Interesting.

Re: Low Cost Encoders
 

I will be glad to take one apart and photograph the guts.
At that point it should be clear if these are actually a knock off.

Re: Low Cost Encoders
 

If you google "rotary encoder" you'll find 100's of companies that produce encoders that look nearly identical to these ones. Who copied who? No one really knows.You pay a premium to buy from American companies like Industrial Encoders because they don't just sell encoders they sell a product that comes with technical support and the guarantee that you'll get a perfectly calibrated encoder that will last years. This is great for a company like HAAS but not necessary for most teams. The end product is almost entirely different.

Re: Low Cost Encoders
 

I wouldn't be so quick to say a lower quality encoder is sufficient for our use.

If the lower quality means an increased failure rate, we'd pass on that. The encoders we get from us digital aren't crazy expensive, and we'll always pay to not lose matches due to preventable failure.

Re: Low Cost Encoders
 

We have no way of knowing the quality of anything until tested.
Even then even it's maybe 3 encoders out of who knows how many lots.

Frankly there are way more ways I can think of ruining encoders in general in FIRST than there are ways I can imagine these are complete junk from my first examination.

There is literally a bag of ruined U.S. Digital encoder parts floating around our workshop.
Each has a story.
However one way or another we have limited our exposure to the U.S. Digital encoders.

Not saying it's U.S. Digital's fault.
Just saying we'll be using sealed encoders where possible in the future.
Though they may or may not be the encoders in this topic.

Re: Low Cost Encoders
 

Interesting, we've run at least 2 (and as many as 8) Us Digitial s4's on every robot since 09 without a single failure. Practice bots and multiple offseason bots included.

Re: Low Cost Encoders
 

Glad they are working out for you.
We've not been so lucky.

Sometimes it's how they were installed.
Sometimes it's how they got damaged during play.
Often times it's adjusting the disc.
I personally destroyed a pair because of a wiring error with the tiny connectors (my fault and I admit it).
We've had a few that no matter the encoder wheel read unreliably (confirmed with an oscilloscope).
They are often in places that it is just plain hard to work on them.

Plenty of that is us and some of that is just the issue of something delicate in the midst of something not very delicate.

Finally last year we got fed up and ordered some sealed encoders from Digikey and had better success.
They cost more but like you said sometimes it's not worth the savings.
They had 0.1 inch spaced header pins so that reduced the tooling, the connectors and the tails.
Never mind the aggravation of remembering to haul around that extra stuff.

Would I use a U.S. Digital encoder on my own professional stuff?
Sure but my professional stuff is not designed, installed or treated like this.

Re: Low Cost Encoders
 

These encoders aren't really the same as the s4. They're weather sealed and the shafts are supported by ball bearings. The price of an equivalent Industrial encoder corp encoders is 200$<.