[TriEmbed] Pinewood derby help

[Glen Smith]

I realize half the fun is building it yourself, but if you any of the pack
Dads are more interested in software than hardware, an LED driver board
might work:
http://www.mtnelectronics.com/index.php?route=product/product&path=67_117&product_id=663
 Built in FET, plus a 7135 linear driver for the low end.
The way the driver is designed, you can re-flash the onboard ATTiny. It
would be interesting to see what different ramping curves of the output
current would do for acceleration.

Glen

On Tue, Jan 10, 2017 at 11:51 AM John Vaughters via TriEmbed <
triembed at triembed.org> wrote:

> Craig,
>
> Sounds like an interesting physics optimization problem. If I am reading
> this right. Still go down hill, but now you have a motor and not just
> gravity as a force.
>
> - When does the weight become a mass drag to the motor?
> - How to use the motor torque speed curves to find optimum gear ratio?
> - All the while trying to optimize acceleration within the race distance
> to make sure motor does not reach max speed and become a drag.
> - Keeping the car straight to not drag the edges by creating optimum
> weight distribution to prevent front back torque caused by motor drive.
>
> I am sure there are more factors, but it sounds like fun to try to
> calculate the physics first and then test the ideas with all the great low
> cost sensors and computing devices we have these days. Or take another
> track and create a statistical study of design parameter method to find the
> optimum, or join the physics and study of design.
>
> All in All Great Fun!!!
>
> The motor drive problem being the the easiest thanks to the great folks on
> this list. For me, I prefer the optical isolated drive methods, but that is
> because I am intellectually lazy and just use what works and is easy to do.
> It is always nice to see the talented folks on this list analyze this ever
> reoccurring question on motor drive circuits. I always learn more, every
> time it is brought up.
>
> Let us know how you do in the competition and how the final design looked.
>
> Thanks,
>
> John Vaughters
>
>
>
>
> On Monday, January 9, 2017 8:47 PM, Craig Cook via TriEmbed <
> triembed at triembed.org> wrote:
>
>
> That is very helpful.
>
>
> Just changed my order to add some TIP120's.
>
> The current motor has a .1 uF cap soldered to both terminals.
>
> I'll make the changes you suggested.
>
>
> Now I need to figure how how to add a "Micro Limit Switch Lever Arm
> Subminiature SPDT Snap Action" into the picture.  When the starting gate
> drops this should activate and turn everything on.  I'll be working on that
> waiting for my order.
>
> Appreciate everyone's help.
>
>
>
> Thanks
>
> Craig
>
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