Yet another Arduino based track timer...

DIY timing systems
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Vitamin K
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Re: Yet another Arduino based track timer...

Post by Vitamin K »

Indy, it's been a hot minute since you've posted this, but do you think you could share some more details on the foam supports you use for the phototransistors for the finish line? I'm getting right to where I need to start building the timer for the track (Our race is in just over a month :eek: ) and I need to figure out how I'm doing it.
Indy wrote: Sun Nov 06, 2016 3:57 pm
Vitamin K wrote:Very cool! I also heard you were onhand to help with the Guinness Book world record attempt, so props for that too!
Thanks! It was a lot of fun to be involved in that effort. Here's a picture of the timer I built for them:

Image

A few interesting notes of the build:
  • the timer could measure up to 9 minutes, 59.99 seconds
  • a filtering circuit was added to the start gate input to handle spikes induced by the 1,800 feet of wire
  • a 1x4 matrix of displays was utilized on both sides to show times as 1:16.7, unused portions of displays were masked by enclosure
  • building the enclosure took the most time (by far)
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Re: Yet another Arduino based track timer...

Post by gpraceman »

Vitamin K wrote: Mon Jan 13, 2025 7:02 am Indy, it's been a hot minute since you've posted this, but do you think you could share some more details on the foam supports you use for the phototransistors for the finish line? I'm getting right to where I need to start building the timer for the track (Our race is in just over a month :eek: ) and I need to figure out how I'm doing it.
Indy wrote: Sun Nov 06, 2016 3:57 pm Thanks! It was a lot of fun to be involved in that effort. Here's a picture of the timer I built for them:

Image

A few interesting notes of the build:
  • the timer could measure up to 9 minutes, 59.99 seconds
  • a filtering circuit was added to the start gate input to handle spikes induced by the 1,800 feet of wire
  • a 1x4 matrix of displays was utilized on both sides to show times as 1:16.7, unused portions of displays were masked by enclosure
  • building the enclosure took the most time (by far)
Looks like the foam packing material that many products come with. In that case it looks like several layers of that foam glued together.
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Vitamin K
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Re: Yet another Arduino based track timer...

Post by Vitamin K »

My timer is almost finished, and...wow, that's a lot of wires all over the place.

Does anyone have any suggestions on what I could use to make an easily detachable plug to connect/disconnect the phototransistors at the base of the timer from everything else? Right now I have a bunch of leads going into a breadboard and that's not great for letting anyone who doesn't know how I've got it wired up to use.

I've got 5 lanes on the timer, so it seems like I'd need a plug that's got 6 pins? (5 signals and one shared ground).
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Re: Yet another Arduino based track timer...

Post by exoray »

Vitamin K wrote: Wed Feb 05, 2025 7:45 amDoes anyone have any suggestions on what I could use to make an easily detachable plug to connect/disconnect the phototransistors at the base of the timer from everything else?
Not sure how it's designed, there are a lot of PCB to PCB plugs out there nowadays, if you make each sensor a plug in module and put the opposite plug on the base, so they could simply be plugged in to the fixed base, if you want the entire base to be removable, may I suggest an RJ45 jack on the timer and base and just use a short network cable to interface them, or even a DB9 serial cable, or even cleaner a 10 conductor ribbon cable where you could alternate signal/ground...

A picture or two might give me more ideas, I did freelance electronics design as job for many years so my mind if full of solutions...
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Re: Yet another Arduino based track timer...

Post by Vitamin K »

exoray wrote: Wed Feb 05, 2025 3:11 pm
Vitamin K wrote: Wed Feb 05, 2025 7:45 amDoes anyone have any suggestions on what I could use to make an easily detachable plug to connect/disconnect the phototransistors at the base of the timer from everything else?
Not sure how it's designed, there are a lot of PCB to PCB plugs out there nowadays, if you make each sensor a plug in module and put the opposite plug on the base, so they could simply be plugged in to the fixed base, if you want the entire base to be removable, may I suggest an RJ45 jack on the timer and base and just use a short network cable to interface them, or even a DB9 serial cable, or even cleaner a 10 conductor ribbon cable where you could alternate signal/ground...

A picture or two might give me more ideas, I did freelance electronics design as job for many years so my mind if full of solutions...
Image

Kind of a mess, as you can see...

The RJ45 jack sounds like a solid idea.
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Re: Yet another Arduino based track timer...

Post by exoray »

My biggest word of advice, since there are so many PC board group buy sites now where it's easy to get a custom-made PCB, I would get rid of that stab to connect breadboard and do all solder joints on a custom PC board because trust me as that thing sits in storage and is moved around those stab to connect will start to oxidize and you will get intermittent issues or total failure on connections... Breadboard and solder!

I know the horrors of wire messes all too well, I built a large light tree for my races and when I was done, I'm like where do all these wires come from!

RJ45 is honestly great for the DIYer vs other proprietary jacks, I used it in a lot of my designs, perfect for low voltage interfacing and everyone knows how to plug it in and if the cable is lost even if longer a replacement cable can be had easily... For me it was really ideal in my low production runs as I could almost always find an over the counter network cable in the correct length vs having to make them, saved a lot of time...
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Re: Yet another Arduino based track timer...

Post by Vitamin K »

Would you have a recommended part for an RJ45 socket?
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Re: Yet another Arduino based track timer...

Post by exoray »

Vitamin K wrote: Wed Feb 05, 2025 6:25 pm Would you have a recommended part for an RJ45 socket?
As to not overwhelm you with options like Mouser or Digikey, try https://www.jameco.com/ if you plan to make your own PC board, if you want to keep it more simple for now, hit up Amazon and search for "rj45 breakout" all sorts of flavors of breakout boards that might appeal to you...
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