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1  Topics / E-Textiles and Craft / Light Emmiting Fabric on: January 16, 2012, 03:03:19 am
Hello

I wonder if light emmiting fabric exists. Or Light emmiting  paint? Where could I found thoses? Because I'm afraid that leds won't fit the purpose as a whole fabric could.

Thanks
2  Topics / Robotics / Re: Position of a servo on: January 11, 2012, 04:57:28 am
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I didn't mean to a servo's internal pot, just an external normal standard pot if I wanted to measure a rotational angle position. A servo has maybe 180 degree travel, a pot has 270 degrees or so. What does using a servo to read a mechanical angle position have over using a standard linear pot? Actually a optical quadrature encoder is my favorite device for measuring angle rotation.
I almost agree with you BUT, external pot means that I'll have to mechanicaly link the servo to the pot. And I don't want to do that. I don't want to do anything that involves my shaky hands.   smiley-grin

Note: I bought a servo GWS 136L STD: 80N.cm 0.33/60°
Very powerful for my application. In fact,.. too powerfull
I now understand:
Quote
Note that you can potentially damage a servo by turning the servo horn by hand
it was so hard (too hard) to turn with my hands.
I think that at last I will do my own servo motor with my own pot, motor,..
That way I'll have all my desire except good looking.

Thanks

3  Topics / Robotics / Position of a servo on: January 09, 2012, 04:39:55 am
Hello,
Last week I asked about knowing the position of a stepper: http://arduino.cc/forum/index.php/topic,85616.0.html . Now I'm interested in servos.

I have a servo motor driving a shaft with a coupling (unknown for the moment, but doesn't matter). The shaft turn of about 90°, but not exactly.

I'd like to register the max and min position of the shaft, by moving it by hands.

Is there a way to know them with the servo or will I have to had an encoder or any position sensor?
What happens on the command pin of the servo (not the 5V, not the ground one), if I supply my motor with current, and turn the shaft?

Have a nice day
4  Topics / Robotics / Re: Position of a stepper motor on: January 03, 2012, 01:34:51 pm
Ok i solved the solution, I'll use something like that: http://www.bourns.com/data/global/pdfs/3382.pdf .1 000 000 turn will be enough

Have a nice day
5  Topics / Robotics / Re: Position of a stepper motor on: January 03, 2012, 11:30:51 am
Quote
Does the sytem sees any different between coil beeing face and static to the right magnet or not and still static? or does he sees any difference only when moving BEMF (like the sensorless brushless motor)?

Quote
I recognize most of those words, but not in that order. Sorry.

Ok sorry, I'll try again.
If you supply a coil with current, the motor will spin since the fields of the coil and the magnet are face to face. I call this position: "coil beeing face [...] to the right magnet".
Now you block the shaft of the motor. If you supply a coil with current, the motor will not spin since the fields of the coil and the magnet are face to face. I called this position:"[...] or not"
In both these cases, nothing turns, then there is no evolution of of the magnetical field, then no evolution of the current in the coil, then unuseful... this is how position is known in brushless motor, without sensors.

My question is: Even if there is no difference in coils, is there any difference anywhere that could be used.

Idea n°1 but which needed added hardware:
Rotary encoder: quite expensive If I want to be almost as precise as the stepper

Idea n°2 but which needed added hardware
Hall effect sensor: Because I don't need an absolute position but a relative one. Do any stepper motor have build-in hall effect sensors ? (need to get at least 2 to be as precise as stepper)

PS: I assumed the system was static beacause of the slow rotation speed of hand moving.

I hope this will be more understandable than previous post.
6  Topics / Robotics / Re: Position of a stepper motor on: January 03, 2012, 10:26:53 am
Thank's for the answers.

What if I supply one coil with a low  (or very low current), I'd be able to turn it with hands.

Does the sytem sees any different between coil beeing face and static to the right magnet or not and still static? or does he sees any difference only when moving BEMF (like the sensorless brushless motor)?

This is damn annoying to be able to be very precise but still beeing blind smiley-confuse

7  Topics / Robotics / Position of a stepper motor on: January 03, 2012, 09:42:56 am
Hello

I have a stepper motor driving a shaft with a coupling (unknown for the moment, but doesn't matter). The shaft turn of about 90°, but not exactly.

I know i can know the position of a stepper motor, but it's always open-loop.

I'd like to register the max and min position of the shaft, by moving it by hands.

Is there a way to know them with a stepper or will I have to had an encoder or any position sensor?

Have a nice day
8  General Category / General Discussion / Re: How many? on: September 01, 2011, 03:09:15 am
This is finished!

BUT 2.6Mo

I'll make a pdf print. If someone need the excel I can send it.

Have  a nice day
9  General Category / General Discussion / Re: How many? on: September 01, 2011, 12:23:15 am
sorry
number of subscribe
10  General Category / General Discussion / Re: How many? on: September 01, 2011, 12:18:28 am
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How is the list of names, many of which just look like gibberish, at all helpful?
I'm not looking for real and precise numbers. But number of inscription gives a tendancy.

About privacy, I would agree with you If I'd use the names, adresses,.. But I just count. I count users and messages.

I'll put different charts:
-Brutal chart: nb of inscription per day
-Brutal monthly chart: per month
-Not so stupid chart: keep only those who post message.

As I may have not explained before, I'm looking for the tendancy of OSH, and not only Arduino. Number of active Arduino users is less significative than users registered I think.

Nice day
11  General Category / General Discussion / Re: How many? on: August 31, 2011, 06:55:24 am
Actually I'm doing the chart manually. I'm  in  2010 - 05 - 14. I made a first chart. I'll post it when finished, with some questions. You'll see it's very interesting.
Good day
12  General Category / General Discussion / Re: How many? on: August 31, 2011, 02:10:21 am
I'll answer robtillart his first question:
This is both personal AND commercial interest information. I'd like to explain the evolution of OSH for a Businees plan I'm sitting at a "contest" (can't find a better word sorry). As I think OSH carries a spirit (like I said before: knowledge sharing, reasonable design), which goes a better way (for people and environnement), than classical design. I think we can all agree about that. So OSH business have nothing to be ashamed of, in fact the more there is the better.


Now you showed me the list of members, i tried to copy paste into a spred sheet. But there are about 1700 sheets to copy paste. So after a litlle try it you take me around 10 hours to have the full list (without crashes ... ). I wonder if any moderator could send me, or everyone interested in fact, the full list? In fact a few informations are needed: date of incription, number of posts, name or number of identification, last post if possible, localisation if possible.

About the poll, I think only a few would answer it and they won't be representative of the whole OSH community (to my mind, but i can be wrong)
 

Have a nice day
13  General Category / General Discussion / How many? on: August 29, 2011, 05:28:44 am
Hello,
I'd like to know if anyone around here have any idea of how many we are?
By we I meen, hackers, arduino users, electronic junkies, designers, artists, engineers,...

I think nobody can have any idea about that, but a first approximation would be to know how many arduini (can i write that? Italian isn't it?) have been sold during last years. Knowing how many arduinos have been sold each year might been interesting too, to know how OSH, and knowledge sharing, spread.

I may have another way too to know how much we are: maybe counting the number of projects would be a first approximation too.

Have a nice day, and if you have any numbers I'm talking about, I'd be VERY interested.
14  Using Arduino / LEDs and Multiplexing / A third interrupt on UNO on: February 21, 2011, 03:46:15 am
Hello,
I'd like to know If there is a way to add a third interrupt on UNO.
Thanks
15  Using Arduino / General Electronics / Max amperage on: February 14, 2011, 07:14:08 am
Hello
What is the max the max amperage the arduino mini 5V pro used? I want to put a Polyswitch before the supply od the arduino in order to protect it.
Thanks
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