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1  Community / Bar Sport / Re: I want to get into 3d printing... on: November 20, 2012, 05:09:26 pm
This guy has some pretty reasonable full kits: http://printrbot.com/shop/  What's your impression of his machines?
2  Community / Bar Sport / Re: Genius behind resistors stripe code and electrolytic cap wire length? [rant] on: November 19, 2012, 04:50:46 pm
I can read the resistor color codes just fine... EXCEPT when they decide they're going to use all pastel shades for the codes and put them on 1/8th watt resistors...  Hmmm, is that lavender or gray?  I mean if you're going to use a color code, make the colors easily distinguishable, especially if the part is really small.  Of course at my age the extra light and magnification thing is a must as well.
3  Community / Bar Sport / I want to get into 3d printing... on: November 19, 2012, 02:50:54 pm
...but I haven't the foggiest how or where to get started.  I'm in the United States and if possible, I'd like to purchase domestically (if for no other reason than to cut down on shipping costs, increase the ease of support and such).  I understand there are three options for this.  1.  Build everything yourself from scratch, 2.  Buy a parts kit and assemble it (preferably one with all the parts as opposed to having to source some unobtanium here locally) -or- 3.  Buy a fully assembled unit.  But I have issues with each approach.  The first approach infers a level of knowledge that I do not possess.  I'm probably MacGiver-ish enough to cobble together a serviceable Cartesian table complete with steppers and driver circuitry... but the print head and control circuitry, yeah that gives me the willies.  I just don't know enough.  The second and third approach suffer from a common malady...  Either I'm too dense to find places that offer them or they are rare as hen's teeth.  The third approach seems to lead down one of two trails... Either too danged expensive or too danged expensive and very proprietary.  Unfortunately I haven't any spare body parts to part with.  The second approach is probably the most practical for me, if only I could find a good reputable retailer that offered kits.  Could someone with knowledge provide me with the Cliff's notes for how to get started with this and where to source things?  Also can someone give me kind of an intro into the software tools that one can use?  (I have some 3d modelling experience) I would greatly appreciate any help and pointers that you can give.
4  Using Arduino / Sensors / Re: Mouse traps on: October 31, 2012, 06:02:11 pm
LOL! I was thinking of a catapult to flick them into the neighbor's yard, not some fancy electrocution device...  But that's just how I am!
5  Using Arduino / Sensors / Re: Mouse traps on: October 31, 2012, 05:40:27 pm
That's pretty sweet.  Ever consider using an emitter/detector pair to trigger the trap?  Perhaps you could use that as the trigger for a longer series of events that would not only trap the mouse, but also remove it from the attic; thus totally eliminating your need to visit the attic.
6  Using Arduino / Sensors / Re: Sensing the impact of a projectile on: October 31, 2012, 05:33:59 pm
The problem here is an issue of false positives.  It would be a torso sized target attached to a mobile base.  The issue gets more complex in that the base should be remotely controllable... Allowing for realistic engagement scenarios (a fleeing suspect, a dodging suspect, etc...)  This means that not only do we have to detect the impact of the projectile on the target, but also billboard the target to the firing-line; always presenting the striking surface to the shooter.  I was hoping to divide and conquer.  Handle the detection first then the billboarding issue second.

I have setup a piezo element on a static target with the hopes that I can fire a few rounds through it and graph what is returned from it with an arduino... however weather and work have been conspiring against me.  When it's nice enough to go shoot, I have to work and when I don't have to work, it's been hideous out.

So As I've been mulling this issue over in my head, I thought of something... ballistic chronographs (such as this one).  These devices detect the passage of a projectile between two sensors and thus cab calculate the projectile's velocity.  Perhaps a similar sensor could detect the passage of the projectile into the face of the target...  So now to figure out how those gizmos work...
7  Using Arduino / Sensors / Sensing the impact of a projectile on: October 16, 2012, 04:44:16 pm
I was speaking with a friend of mine who is a police officer. The topic arose of a need for a moving target on their practice range.  I thought it would be a neat idea to mount a pop up target on a RC controlled mobile base.  It would be best if we could detect the impact of a projectile on the target surface and in response, drop the target.  The target surface would need to be disposable/replaceable and the electronics should not be destroyed when detecting the impact.  How might one accomplish such a thing?  Clearly, the mobile base would need to be armored against unintentional bullet strikes as well.
8  Community / Bar Sport / Inverse Kinematics on: February 03, 2011, 04:04:22 pm
I'm interested in learning more about inverse kinematics.  Does anyone know of any good online resources for studying the topic and the underlying mathematics that are involved?
9  Using Arduino / Motors, Mechanics, and Power / Re: Using a solenoid to kick a ball on: January 28, 2011, 04:07:55 pm
What about using mechanical advantage to increase the speed of the blow delivered to the ball.  If the solenoid were attached to the shorter side of a pivoting arm (a lever), then the longer free end of that arm were used to impact the ball, you might get better kicking distance because of the increased speed. 
10  Forum 2005-2010 (read only) / Interfacing / Re: Running LCD display and tlc5940 simultaneously on: December 03, 2009, 08:56:55 pm
The TLC5940 has an SDI interface.  Therefore the TLC5940 library probably references the wire library directly -or- has inherited large portions of it via copy/paste coding or uses the same tactics and techniques to deal with the same issues.
11  Forum 2005-2010 (read only) / Interfacing / Re: Running LCD display and tlc5940 simultaneously on: December 03, 2009, 07:43:36 pm
I'll bet you're dealing with the same issue I am.  There seems to be a conflict between liquidCrystal.h and wire.h.  Here's my thread on the issue.
12  Forum 2005-2010 (read only) / Interfacing / Re: Non-linear resistance in a digital potentiometer on: January 07, 2011, 05:11:05 pm
Um, dumb question for newbs like me...  What's the difference between a potentiometer and a rheostat?
13  Forum 2005-2010 (read only) / Interfacing / Re: detecting obstructions on the sea on: December 08, 2010, 07:25:46 pm
I seem to remember reading somewhere that capacitance could be used to detect nearby bodies in water...  Somewhat similar to a the way a theremin works.
14  Forum 2005-2010 (read only) / Interfacing / Re: unable to read ir sensor value on: November 24, 2009, 07:14:48 pm
Use a digital camera to tell if the IR LED is functioning at all.  The CCD is sensitive to IR wavelengths and it will show you the LED lit if it is.
15  Forum 2005-2010 (read only) / Interfacing / Re: unable to read ir sensor value on: November 24, 2009, 06:43:33 pm
Could it be that you've placed the IR LED in the place of the IR Transistor?  In a lot of cases they do look similar.  
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