Search found 272 matches

by SlartyBartFast
Wed Feb 12, 2014 1:53 pm
Forum: Do-It-Yourself
Topic: State of the art in timers?
Replies: 6
Views: 13045

Re: State of the art in timers?

gpraceman wrote:Ah, you were talking about electronic timing without using a microcontroller.
Sorry for not being clear.
by SlartyBartFast
Tue Feb 11, 2014 4:05 pm
Forum: Do-It-Yourself
Topic: State of the art in timers?
Replies: 6
Views: 13045

Re: State of the art in timers?

Just revisiting, in the past I had a few discussions where people were concerned about the errors that might be induced by poorly written firmware and interrupt handling. Taking a good look at the Swan-Tech timer I realise that even that is a PIC microcontroller based timer. Guess even when computer...
by SlartyBartFast
Tue Feb 11, 2014 8:24 am
Forum: General Topics
Topic: Weight Placement
Replies: 38
Views: 48493

Re: Weight Placement

pitching axis and CoM axis: I don't mind admitting that there is far more theory and math in the link than I care to try to wrap my head around. But my mind screams out when I read "CoM axis". Just the simple physical reality of the car/track interface, in my mind, shows the impossibility...
by SlartyBartFast
Thu Feb 06, 2014 9:04 am
Forum: General Coordinator Topics
Topic: Have you seen issues with fixed axle location rules?
Replies: 13
Views: 30447

Re: Have you seen issues with fixed axle location rules?

The car can be any length just not over 7". The unnecessary wood behind the rear wheels is moved to the front to take advantage of the "Front End Extension Effect". Shifting the wheelbase moves the CM higher up the arc. Always struck me as odd that maximum nose and tail length from t...
by SlartyBartFast
Wed Feb 05, 2014 10:43 am
Forum: General Topics
Topic: Weight Placement
Replies: 38
Views: 48493

Re: Weight Placement

I have followed usual practice of analysis ... first analyze the energies as the components of the car rotate about the car's (moving) CM, then, second, analyze the energies as the car's CM rotates about the track's center of curvature. If you choose a point on the car other than its CM, then the s...
by SlartyBartFast
Wed Feb 05, 2014 9:27 am
Forum: Do-It-Yourself
Topic: State of the art in timers?
Replies: 6
Views: 13045

Re: State of the art in timers?

Anyone try a Rasberry Pi? Sounds yummy. I haven't heard of anyone using Raspberry Pi as a timer. The Arduino plans posted by Indy are a good option for the DIYer not looking to reinvent the wheel. http://www.derbytalk.com/viewtopic.php?f=5&t=6216" target="_blank Oh come on gpraceman! ...
by SlartyBartFast
Wed Feb 05, 2014 8:48 am
Forum: General Topics
Topic: Weight Placement
Replies: 38
Views: 48493

Re: Weight Placement

Here we go again, I come back from a long hiatus and get sucked in to thinking these things through and I start jumping in on threads (probably half-cocked). I often wonder if these discussions are using terms in way that I am familiar and whether the armchair physicists have it right and my brain i...
by SlartyBartFast
Tue Feb 04, 2014 3:09 pm
Forum: Do-It-Yourself
Topic: State of the art in timers?
Replies: 6
Views: 13045

State of the art in timers?

What's the latest preferred flavour for DIY timers? I see Arduinos mentioned. Anyone try a Rasberry Pi? Traveling down memory lane, I remember preparing the circuit diagram for an expandable latching counter. Each sensor latched a counter for that lane. It was modular and simple. Can't remember if I...
by SlartyBartFast
Tue Feb 04, 2014 12:19 pm
Forum: General Topics
Topic: Two Year Hiatus, Anything New?
Replies: 5
Views: 7867

Re: Two Year Hiatus, Anything New?

FatSebastian wrote:Please define "bridge free".
No "over the track" structure for the timing electronics.
by SlartyBartFast
Tue Feb 04, 2014 11:27 am
Forum: General Topics
Topic: Two Year Hiatus, Anything New?
Replies: 5
Views: 7867

Re: Two Year Hiatus, Anything New?

So you actually bothered to check? I'm surprised anyone remembers my ramblings. Guess I posted enough (quantity over quality?) to leave a mark with one or two regulars. But my old derby cars are on a shelf in my kitchen and never far from mind. I lament that there is no derby in my son's scouting gr...
by SlartyBartFast
Tue Feb 04, 2014 8:58 am
Forum: General Topics
Topic: Two Year Hiatus, Anything New?
Replies: 5
Views: 7867

Two Year Hiatus, Anything New?

It has been two years since my last post. So, what's new and exciting in the world of derbies? All the latest topics look eerily familiar. ;) Still have a soft spot for derby cars and tech, so when I came across the following sensor I thought "Derby finish line!". http://www.walkeremd.com/...
by SlartyBartFast
Sat Mar 10, 2012 3:04 pm
Forum: Do-It-Yourself
Topic: Adding a Friction Brake to an Old Track
Replies: 48
Views: 71519

Re: Adding a Friction Brake to an Old Track

Has no one thought about using gravity to slow the cars down?

If the track curved upwards in the stopping area, gravity would help stop the cars.
by SlartyBartFast
Thu Oct 14, 2010 2:14 pm
Forum: Do-It-Yourself
Topic: Wireless Timer to Computer Connection
Replies: 0
Views: 10910

Wireless Timer to Computer Connection

haven't been around here in along time, but looking at electronics again made me think of derbytimers...

Seems that a pair of these would make a good wireless interface between a timer and a USB equipped computer.
http://ladyada.net/make/xbee/index.html" target="_blank
by SlartyBartFast
Thu Oct 14, 2010 12:33 pm
Forum: General Off Topic
Topic: Applying my PWD experience to a robot
Replies: 6
Views: 11049

Re: Applying my PWD experience to a robot

Post the rules! Any PWD racers knows that the first step is to find the loopholes! My university had robot sumo wrestling. Two robots in a circle, one needs to put the other outside the circle. I got banned from competition after reading the rules and explaining my planned entry to the people in cha...
by SlartyBartFast
Sun Jan 03, 2010 11:33 pm
Forum: Car & Semi-Truck Construction
Topic: How come no one puts aerodynamic "fenders" on cars?
Replies: 69
Views: 63913

Re: How come no one puts aerodynamic "fenders" on cars?

SlartyBartFast, The Cavity is fully exposed to air flow either way the Wheel faces. The consensus is that when mounted normal the Cavity picks up air turbualnce off the car body and slows the car down. Without tests and data, I find this one hard to believe. :paperbag: I'm trying to come to terms w...