Bryan Bonahoom | 7 Jan 04:47 2011
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Brickworld 2011 - Registration Open

Hello everyone,

We are happy to announce that Brickworld registration is now open. We have been
hard at work performing a complete overhaul on the registration process. In
response to your feedback in the survey after last year's event, we have done a
couple things to the event. Some items that impact registration:

1.There are now 2 types of registration: Full and light. These are described on
the web site. But, essentially, full registration is for someone that is
contributing to the event and partaking in the workshops and presentations.
Light registration is for families that want to show up Friday afternoon, see
the event hall without the public, participate in weekend non-public activities,
and learn from the AFOLs and TFOLs.

2.The full registration will be capped at 650 people to keep things from being
unmanagable.

3.When you register for the event, you aren't considered registered until you
pay (the new process leads you through this)

4.The event will start on Wednesday evening with opening ceremonies later in the
evening. This will lead to having most of the display space available for MoC
setup starting on Thursday morning instead of Thursday evening. Essentially, we
are spreading the event out a bit so it is more relaxing for everyone. The
survey feedback indicated there was too much happening in too small a space in
time.

Don't forget to sign up for your hotel rooms too. Last year the hotel filled up.
And, if you are a first time attendee, everyone will tell you that it makes the
event a lot more fun to be at the hotel.
(Continue reading)

Philippe Hurbain | 12 Jan 11:02 2011
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Motors comparison page updated

My [<http://www.philohome.com/motors/motorcomp.htm motors comparison page>] now
includes tests of the E-motor from <http://www.brickset.com/detail/?Set=9688-1
Renewable Energy Add-On Set (9688)>.

<http://www.philohome.com/motors/motorcomp.htm
<http://www.philohome.com/motors/motors4.jpg>>

Enjoy!

<http://www.philohome.com/index.htm Philo>

Brian Davis | 12 Jan 21:40 2011

Re: Motors comparison page updated

In lugnet.announce, Philippe Hurbain wrote:

> My motors comparison page now includes tests of the E-motor...

Thank you! Surprising that with as easy as it is to backdrive, that the
efficiency is as low as it is.

Out of (not idle) curiosity, is it possible to drive even more current-hungry
devices safely from the NXT? I need a way to drive a 120V AC, 15 amp device
under NXT control (I need to be able to cycle it on/off rapidly with a variable
duty cycle, to control average power output).

--

-- 
Brian Davis

Philippe Hurbain | 13 Jan 09:31 2011
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Re: Motors comparison page updated

Hi Brian,

> Thank you! Surprising that with as easy as it is to backdrive, that the
> efficiency is as low as it is.

I was surprised too. I suspect a relatively high internal resistance of the
windings, rather than mechanical friction, as the source of losses. No, (shame
on me!) I didn't checked yet with an ohmmeter.
>
> Out of (not idle) curiosity, is it possible to drive even more current-hungry
> devices safely from the NXT? I need a way to drive a 120V AC, 15 amp device
> under NXT control (I need to be able to cycle it on/off rapidly with a variable
> duty cycle, to control average power output).
This is clearly outside of my own SOA there
(http://en.wikipedia.org/wiki/Safe_operating_area)! Are you sure that duty cycle
modulation works with this kind of AC motor? You would need to synchronize with
mains... Or - to keep it simple and safe - you might try to control the dial of
a powerful light gradator with a NXT motor?

Philo

Brian Davis | 13 Jan 13:59 2011

Re: Motors comparison page updated

In lugnet.robotics, Philippe Hurbain wrote:

> This is clearly outside of my own SOA there!

I've been operating outside my personal SOA for years now :)

> Are you sure that duty cycle modulation works with this kind of
> AC motor?

It's actually not a motor - it's a small electric hot water heater element. When
plugged in it produces 1300W, but if I want less than that I need to figure out
some way to reduce the current, or the voltage... or, alternatively, cycle it on
and off very rapidly. 1300W on for 1 sec and then off for one sec should
simulate a power output of 650W, for example. But if the cycle time starts
drifting up above 1 sec, it will induce thermal oscillations in the system I
don't want... so switching something like this off/on rapidly seems to be a good
option.

> ...to keep it simple and safe - you might try to control the
> dial of a powerful light gradator with a NXT motor?

That was actually my first thought (in fact using a "dimmer switch" manually
would be good enough... I really just need a way to set the power output, no
absolute need for NXT control). The problem is nobody needs to "dim" 1300W light
sources, and worse, most of these dimmers work by dissipating and dropping the
power in the dimmer, not the light... meaning in this case you don't save power,
and the dimmer gets... really warm.

What I've got now is a wall switch in a small wooden box, with a LEGO framework
pinned to it with an NXT motor. The motor is used to simply throw the switch
(Continue reading)

Philippe Hurbain | 13 Jan 15:02 2011
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Re: Motors comparison page updated

> It's actually not a motor - it's a small electric hot water heater element. When
Good thing, the load is not inductive.

> plugged in it produces 1300W, but if I want less than that I need to figure out
> some way to reduce the current, or the voltage... or, alternatively, cycle it on
> and off very rapidly. 1300W on for 1 sec and then off for one sec should
> simulate a power output of 650W, for example. But if the cycle time starts
> drifting up above 1 sec, it will induce thermal oscillations in the system I
> don't want... so switching something like this off/on rapidly seems to be a good
> option.
OK, with a 1 second cycle time, and pure on/off, it is simpler. All you need is
a solid state relay.
>
>> ...to keep it simple and safe - you might try to control the
>> dial of a powerful light gradator with a NXT motor?
>
> That was actually my first thought (in fact using a "dimmer switch" manually
> would be good enough... I really just need a way to set the power output, no
> absolute need for NXT control). The problem is nobody needs to "dim" 1300W light
> sources,
Looks like some people do:
http://www.amazon.com/Leviton-61500-I-Single-Pole-Electro-Mechanical-Incandescent/dp/B003AUDF0Y/ref=sr_1_1?ie=UTF8&s=hi&qid=1294925232&sr=1-1

> and worse, most of these dimmers work by dissipating and dropping the
> power in the dimmer, not the light... meaning in this case you don't save power,
> and the dimmer gets... really warm.
>
Fortunately no, they are not dissipating all the power not going in the load! (a
triac controls load as on/off at mains frequency for a fraction of cycle) But of
course there are somme losses - 2 to 3 V drop at 15A gets a small box quite warm
(Continue reading)

Steve Putz | 13 Jan 19:10 2011

Re: Motors comparison page updated

In lugnet.robotics, Philippe Hurbain wrote:
>> It's actually not a motor - it's a small electric hot water heater element...

Interesting thread, even if a bit off topic of LEGO motors.  I'm not an expert
on power circuits, but a google search turned up this web site with a number of
interesting power supply circuits (there is a search option).

    http://powersupply.circuitelectronic.net/

Steve Putz
http://www.RoboticsLearning.com

Brian Davis | 15 Jan 04:29 2011

Re: Motors comparison page updated

In lugnet.robotics, Philippe Hurbain wrote:

> Good thing, the load is not inductive.

No, purely resistive. Although it does have a "boot up" time, I think it's just
due to heating up the element. I'm not completely sure if the element will
respond better to a "dimmer" type set-up (running it at less than normal
voltage) or a "pulsed" set-up with a relay... but with the relay I'd have
all-electronic NXT-based control, which I really like.

> Looks like some people do:
> http://www.amazon.com/Leviton-61500-I-Single-Pole-Electro-Mechanical-Incandescent/dp/B003AUDF0Y/ref=sr_1_1?ie=UTF8&s=hi&qid=1294925232&sr=1-1

Wow! Thank you, I didn't realize they made those (although they aren't cheap...
but it's at least viable).

> Fortunately no, they are not dissipating all the power not going
> in the load!

Thanks for that tidbit as well... I wasn't aware of that, and was worried about
it.

--

-- 
Brian Davis

opals | 18 Jan 07:13 2011
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Re: Lots of gratitude


Dear Brahm,

We know we are not supposed to do this on this forum, but we shall do it
anyways because our gratitude towards you is more intense than just a 5 star
rating. We have been trying to make our RIS 2.0 software and hardware work
for many and many hours. Your tips , combined with other patches and apps,
have finally led us to achieving our goal. We will now be able to power our
insane robot project and be able to program it. 

Many thanks from Montreal, Canada, and we wish you the best for 2011!

Felix and Laurent

--

-- 
View this message in context: http://old.nabble.com/Asking-for-RIS-2.0-patch-under-Windows-XP-tp18298813p30697519.html
Sent from the LEGO Robotics mailing list archive at Nabble.com.

Dave Curtis | 25 Jan 01:09 2011
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Anyone else tried the Firgelli actuators?

I decided to spring for one of the expensive Firgelli actuators, and just gave
it a quick try.  I either got a broken unit, or it is the worst piece of junk
anyone has ever made for NXT.  First of all, you command it to move a distance,
not command it to a set location like you would expect for a servo.  OK, I can
live with that, but if I command it to move 10mm, some times I get 7, sometimes
I get 12, sometimes I get 20mm, and sometimes it just goes all the way to the
end stop.  Totally el-flako useless. 

Anyone else had any experience with these things?  Did I just get a lemon?


Gmane