single lane derby car timer with optical start - stop

[Tonytee]

Hi, I am trying to build a derby car timer. I need a circuit diagram (Probably something like what that guy is using for his boats) The difference is that I need an optical clock starter at the top of the track, and an optical clock stopper at the bottom of the track. I also need the display to show 1 digit full second display, as well as 4 point second accuracy (Ex: 1.2635 seconds) I am going to use this as a development tool to build the fastest car I can, so that any small modifications would be noticed.

Any Ideas

Thanks,
TT

 

[ronv]

What is the maximum time requirement. Since you are only looking for faster or slower could it just measure in say 1/100 of a second (example 120 = 1.20 seconds) rather than seconds and 1/100 of seconds?

 

[InventionUnlimited]

Why does it need to be optical? I have a simulated qtr mile scaletrix track (slot car?) and just used hot melt glue to stick tiny reed switches to the base of the track and the magnets that are built into the cars trigger them. Works great.

 

[Tonytee]

What is the maximum time requirement. Since you are only looking for faster or slower could it just measure in say 1/100 of a second (example 120 = 1.20 seconds) rather than seconds and 1/100 of seconds?

The total race time length is about 2 to 3 seconds. The track is about 25 ft long. Yes, I guess I could read the time as suggested. I would need to be able to read four digits say 1201. The reason I would like to measure thousands of a second is that slight modifications, like a small angle change might only have a very small change in total time, but I would be able to see if it increased or decreased the total time. Every one thousand of a second reduced eventually adds up to a hundredth. In this type of racing the cars are very close at the finish line because everybody has to use a standard build kit, and all the cars must be very close in weight + - 5 grams. We are allowed to shave the wooden body for aerodynamic advantage, but then we have to add weight to meet the minimum spec.

Thanks for getting back to me.
Much appreciated.

TT

 

[Tonytee]

Why does it need to be optical? I have a simulated qtr mile scaletrix track (slot car?) and just used hot melt glue to stick tiny reed switches to the base of the track and the magnets that are built into the cars trigger them. Works great.

Hi and thanks for your reply.
The derby track is about 25 Ft long, and is basicaly a one shot deal. 4 cars down the track, and the first one at the end wins, then second , and then third. forth place is bumped.
The main track already has a monitoring device at the finish line to show 1, 2, and 3 place.
The times at the track are not important, just the finish places.
I am building a test track at home to monitor my elapsed time, so any mods I make on the car can be seen on the timer, to see if the mod increased or decreased my time. Every ten-thousand of a second I can reduce will add up to a hundredth and so on.

I am interested in doing the computer setup. How, and what do I need.

Thanks,
TT

PS These cars are gravity cars not motorized.

 

[ronv]

TT, Lets see how this sounds to you.
1- single lane
2- start and stop time detected with photo cell
3- 4 digit resolution.
4- AC powered (wall wart)

You will need to be pretty handy. It will be a lot of wires to hook up. Do you have any equipment for troubleshooting?
If not it might be better to get most of it off the shelf.
Pinewood Derby Track, Pinewood Derby Timer Headquarters
I would have to do it with hardware cause I'm a Microprocessor illiterate. Maybe a u guy will come up. It would be better.

 

[MrDEB]

25 foot track in 4-5 seconds --YOU NEED MORE SPEED!!
I have a pinewood derby car and a 50 foot track. Start gate is 5.5feet high with about a 45 degree slope.
straight flat length is 35 feet aprox.
Have gone 2.8 seconds from start to finish. NOTE this is a STOCK car weighing 5 oz w/extended wheel base.
easiest method to display/record et is using a microcontroller and either an LCD display or LED. could even use a computer.
our cub pack has a pinewood derby race every year. my challenge is if you beat my car you get to put a cream pin in my face. hasn't happened yet.

 

[Tonytee]

TT, Lets see how this sounds to you.
1- single lane
2- start and stop time detected with photo cell
3- 4 digit resolution.
4- AC powered (wall wart)

You will need to be pretty handy. It will be a lot of wires to hook up. Do you have any equipment for troubleshooting?
If not it might be better to get most of it off the shelf.
Pinewood Derby Track, Pinewood Derby Timer Headquarters
I would have to do it with hardware cause I'm a Microprocessor illiterate. Maybe a u guy will come up. It would be better.

Ya, sounds pretty good to me.

 

[Tonytee]

TT, Lets see how this sounds to you.
1- single lane
2- start and stop time detected with photo cell
3- 4 digit resolution.
4- AC powered (wall wart)

You will need to be pretty handy. It will be a lot of wires to hook up. Do you have any equipment for troubleshooting?
If not it might be better to get most of it off the shelf.
Pinewood Derby Track, Pinewood Derby Timer Headquarters
I would have to do it with hardware cause I'm a Microprocessor illiterate. Maybe a u guy will come up. It would be better.

Hi,
Did you ever get a circuit diagram?

Please get back to me.

THanks,
TT

 

[ronv]

Sorry Tony, some computer problems. It really would be easier with a micro. Give that section a try and come back if you don't get a response and I'll put something together for you.
Do you have a solenoid for the starting line? This would eliminate a sensor if you do.

 

[Tonytee]

Thanks,
I'll check into it

BFN
TT

 

[4pyros]

TT have you ever seen the movie Down and Derby? The kids are suppost to make the cars not you! You are going over board and give the race a bad rap. Stop it YOU take all the fun out of it and let the kids have fun!

 

[MrDEB]

Do a search for MAXIMUM VELOCITY PINEWOOD DERBY
They have a race once a month where you send in your car/cars to race. There's like 7 different classes
Cost is $5 per entry. At the end of the year who ever has the most points per category you win $$$
no small chump change. I recall several years ago the winner in one of the categories won $800
This is not child's play anymore.
Races are put up on the web.

 

[gabeNC]

I always like the outlaw divisions, the crazy stuff people come up with... like this

YouTube - World's Fastest Pinewood Derby Car

 

[4pyros]

Sorry I jumped to the conculshoin the OP was working on his kids car. You are not right?