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Unread 09-02-2011, 12:00
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Re: [FTC]: Samantha? Like it or hate it?

I guess this is where theory vs reality comes into play.

If you assume that those tiny screw terminals provide perfect electrical contact, and that the students wiring said terminals do a perfect job of stripping and inserting the wires, then you are correct.

However, IMHO the reality of the situation is very different. Many kids will nick a few wires when stripping (there goes a few % in cross section). Maybe not all the strands get crimped tightly under the screw (there goes a few % in cross section). Maybe the wires get compressed and as a result it releases the tension from the screw (there goes a few % in cross section and adds a few ohms of resistance). Before you know it, 12 screw terminals (up and back) make the wire look pretty imperfect.

Every mechanical connection is also a potential failure point (complete or partial) and a less than perfect connection provides less than perfect resistance, inductance and capacitance.

Finally, I personally don't know what's between the power in and power out terminals on the servo and motor controllers (since I haven't pulled a controller apart) so who's to say there isn't an inductance that your meter isn't seeing (but a 40A spike will see).

Since these robots get severly beaten around, the more mechanical connections in a chan, the more it increases the likelyhood of an intermittant connection getting noticed.

Since I can eliminate any chance of the Samantha seeing a power glitch from any one of those (14) connections just by splicing off the main switch cable, seems like no-brainer insurance to me.

Phil.

Quote:
Originally Posted by NalaTI View Post
Have to ask the question here (because I honestly don't know the answer)
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Phil Malone
Garrett Engineering And Robotics Society (GEARS) founder.
http://www.GEARSinc.org

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Last edited by PhilBot : 09-02-2011 at 12:03.
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