Afforable rotory optical encoder found

L

leftyretro

New Member
I've spent several months looking for nice industrial grade quality rotory optical encoders on E-bay but just not found anything at nice hobby prices avalible. Finally I stumbled upon B&G micro and they seemed to have a nice price on one without a lot of details provided. I went ahead and ordered two and they arrived today.

They are marked made by OAK/Grigsby, part # 91Q128-43-00410. I assume this means 128 steps per rev.

It has kind of a useless 4 pin connector on the end of the 5 inch 4 conductor solid wire flat cable. I just lopped off the connector and soldered the bare wire ends to a 4 pin header. I placed ground on pin 1 (marked with a stripe) and +5vdc on pin 4. Channel A & B are pins 3 & 2 respectively. I put my two channel scope on pins 2 & 3 and could see very nice quadurture square waves being generated as I turned the knob in either direction. Being optical there should be no contact bouncing like with mechanical encoders and the pules seemed nice and square to me.

The encoder has a nice feel with a solid drag and no detents, feels just like a quality hi-fi volume control feels. The body is 1" square and about 1/2" thick. It uses standard 1/4" knobs, so that is nice.

All in all this is quite the steal for $5 each (or $4 if 4 or more) in my opinion and as I said I've been looking for quite a while. Now I need to decide if owning just two is enough. ;)

Lefty

OPPS, forgot the link: http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12916
__________________
Measurement changes behavior
 
Last edited:
M

MPep

Senior Member
Just had a look at the BGMicro site. It is certainly 128 steps per revolution so that also answers Manie's question, I hope. :D

Although, on the site they ask,
What else could you ask for?
Click to expand...
.
Simple answer: a datasheet!!!:confused:
 
M

manie

Senior Member
Lefty: Any more news on the use/implementation of your encoder ? Would like to know please.
Manie
 
L

leftyretro

New Member
manie said:
Lefty: Any more news on the use/implementation of your encoder ? Would like to know please.
Manie
Click to expand...
Well I can say I'm very pleased with them. I have not posted any actual application testing code that I've been writing to check them out because I'm using an Arduino AVR board, and it uses the C programming language.

I have been able to wire up and read my two encoders at the same time, sending two position integers back to my PC, using just 4 digital input pins. This is using the two hardware interrupt pins the Arduino I/O has available. If I set the interrupts to trigger on rising level I get 128 steps per revolution. If I set to interrupt on change of level I can get 256 steps per shaft revolution. If I just use one encoder and interrupt on both it's two channels I can get 512 steps per revolution.

Today I modified it to also output direction digital outputs and step command digital outputs, one set for each encoder. The plan is to drive a stepper motor & controller I have on order. This should allow me to turn the encoder knobs and have the stepper motor follow in direction and speed, but I'm not sure if I can make it be a one to one step relationship yet till I get to play with it.

All I can add is these are incredibly nice small industrial quality encoders that I'm sure when they sell out will not be available again at the current price if at all. That's what surplus buying is all about, pounce when you have the chance. ;)

I was not happy with the low cost mechanical rotory encoder I bought and tried out. It had pretty bouncy contacts and the mechanical detents didn't seem to stay in sync with the switching action, and they sounded and felt cheap.

Let me know if there is anything more specific you would like to know or have me try.

Lefty
 
Last edited:
M

manie

Senior Member
Lefty: Firstly, my sincerest sympathy with regard to your "C" usage.... I know the pain...
LOL LOL !

So basically you monitor two outputs from the encoder by counting pulses and depending on which one = high or low you know the direction, am I right ? I currently use a wirewound pot to read a car/truck throttle position. It works very well, but it is mechanical and prone to severe wear as used on a throttle pedal. This sounds ideal as there are no wear items, difference is not reading analogue V's, but counts etc. Do you think it can work in this application ?
Manie
 
L

leftyretro

New Member
manie said:
Lefty: Firstly, my sincerest sympathy with regard to your "C" usage.... I know the pain...
LOL LOL !

So basically you monitor two outputs from the encoder by counting pulses and depending on which one = high or low you know the direction, am I right ? I currently use a wirewound pot to read a car/truck throttle position. It works very well, but it is mechanical and prone to severe wear as used on a throttle pedal. This sounds ideal as there are no wear items, difference is not reading analogue V's, but counts etc. Do you think it can work in this application ?
Manie
Click to expand...
Mechanically and electrically it would most likely be an improvement. These are sealed units so no dirt or dust to worry about and as you said no mechanical contacts or wear points other then the main sleeve bearing.

However you would have one challenge and that is what to use if anything as a reference position when you first turn on to establish that the throttle is at a zero position. Without some kind of additional sensor to set what is the starting point of the throttle travel you would have to ensure you never power up and start the processor with your foot on the pedal and your program would have to assume that the throttle position is at 'zero' on start up. That make sense?

Lefty
 
M

manie

Senior Member
Lefty:
The same applies to a potentiometer. You don't know the pedal position at startup so must set high/low limits during Init: As the values change, the max/min values are updated until you know the extremes, but you are sensing voltages so any reading is either higher or lower than setpoint. One will have to carefully read direction and update the correct "limit" value with the encoder.... I think I see some real application for a linear light sensor and LED source. Futurlec sells a linear light sensor, I think I'll use that.
Manie
 
K

krypton_john

Senior Member
retrolefty said:
I've spent several months looking for nice industrial grade quality rotory optical encoders on E-bay but just not found anything at nice hobby prices avalible. Finally I stumbled upon B&G micro and they seemed to have a nice price on one without a lot of details provided. I went ahead and ordered two and they arrived today.

They are marked made by OAK/Grigsby, part # 91Q128-43-00410. I assume this means 128 steps per rev.

It has kind of a useless 4 pin connector on the end of the 5 inch 4 conductor solid wire flat cable. I just lopped off the connector and soldered the bare wire ends to a 4 pin header. I placed ground on pin 1 (marked with a stripe) and +5vdc on pin 4. Channel A & B are pins 3 & 2 respectively. I put my two channel scope on pins 2 & 3 and could see very nice quadurture square waves being generated as I turned the knob in either direction. Being optical there should be no contact bouncing like with mechanical encoders and the pules seemed nice and square to me.

The encoder has a nice feel with a solid drag and no detents, feels just like a quality hi-fi volume control feels. The body is 1" square and about 1/2" thick. It uses standard 1/4" knobs, so that is nice.

All in all this is quite the steal for $5 each (or $4 if 4 or more) in my opinion and as I said I've been looking for quite a while. Now I need to decide if owning just two is enough. ;)

Lefty

OPPS, forgot the link: http://www.bgmicro.com/index.asp?PageAction=VIEWPROD&ProdID=12916
__________________
Measurement changes behavior
Click to expand...
That site is a gold mine. Thanks for the post, Lefty!
 
You must log in or register to reply here.
Top