Rolling my own electronic finish line

redlinederby Tuesday, 6/22/2010
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Okay, I know we've been questing for an all-mechanical DIY finish line, but my laziness got the best of me and after some easy convincing from some co-workers, I caved and bought a microcontroller with plans on building my own electronic finish line.

The controller itself was $30 or so, but the components - the LEDs, resistors, sensors - are all pretty cheap, so I think I can make a kit for less than $50. I'm still waiting on some more components to be shipped before I can do a full two-lane prototype, but so far a one-lane test with a photocell sensor looks promising. I am also going to try the IR sensor again to see which works better. Now that I have control over how the thing works I feel more confident in finding a good balance.

One problem I had with the IR sensor finish line in the past is ambient light. Well, I've accepted the fact that ambient light is a problem I just need to account for. My first attempt at a solution is building in a sensitivity dial that you change based on your environment, high for lots of light, low for darker room. To my surprise it actually worked.

So I'm diving into electronics head first and so far it's turning out pretty well. I'll see what happens when it gets time to solder and actually get all the parts into a nice package, but I'm hoping for the best.

If any of you guys are experienced at soldering or packaging together electronics, please reply or PM me. I might need to pick your brain soon.


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markkaz 6/22/10

Sorry, my knowledge about electronics is pretty limited. That's why
I went with The Judge at to have EFL's made to
fit my size track.

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Bandeezee 6/22/10

Glad to hear someone is making progress on a finish line. If it works well outside in a lot of light I'll need a guide That's the one thing we're missing now (a finish line). Good luck on finishing it, hope it works out.

We finished the starting gate, it's not the best looking thing, but it does it's job. Got some Plexiglas through some metal tubing that goes through a block of wood. We have a screw going into the tubing at the end to act as a lever. When I have a proper wooden support for the track, then I think the starting gate is going to have to be different, but it works for now. I'll try to remember to submit pictures later.

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JDC442 6/22/10

Glad to hear you're pioneering the DIY electronic finish Brian! Once you get your prototype up and working, i'm sure a lot of us will be interested in DIY directions like you gave for the awesome folding track

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Jobe 6/22/10

Yes, electronics and electrical diagrams are a black art to me!

As much as I'd like to go full digital, I kind of like the low-key track I have. It's all Mattel parts!

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JDC442 6/22/10

As much as I'd like to go full digital, I kind of like the low-key track I have. It's all Mattel parts!

I do fully approve of the 'stock' Mattel track!!

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redlinederby 6/23/10
Site manager

I don't mind mechanical or all-toy parts either, that's what I'm running now. But I've found my two-lane finish line to be getting quite a beating. Just from the cars hitting the mid-post or rubbing it. Then if the track is a little off sometimes they careen right into the side, causing crashes. I think my issue with the V-drop finish line is that it's the END of the track instead of the track running through it, which I would prefer.

If I have my way and get this electronic one to work like I want, there will be two outcomes, possibly three:
1) At least, a guide for building one yourself with a parts list and so on
2) A small blackbox kit, similar to this, that you can buy and then add to your setup the way you want
3) At most, a full retail-style setup that you can just add to your track and be done (a la The Judge)

I'm shooting for #2 because I think that will be useful to everyone. I'm not trying to re-invent a Judge type finish line, I'm trying to make something between a parts guide and a retail product...because that's what I was looking for an couldn't find. I don't have the money to buy a $150 Judge, but I also didn't have the electronics knowledge to build one from scratch. If I can create a DIY kit that is $50 or under I'll be very happy.

Worst case, if I can't manage to package it into a nice DIY kit, I'll certainly have the schematic and parts list that I'll post on the site. This electronics stuff is new to me, but the microcontroller is computer programming, which I know very well - so it's a mix of what I know best and what I don't know at all. Pretty fun to learn and figure out in both cases.

I skipped all the silliness and went with another judge. The $300 is worth it in headaches and time savings alone. I got my custom two lane finish line with computer timing, start gate switch, all cables and Sunlight Max (works in full sun) and had it on the doorstep within a couple of days.


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markkaz 7/11/10

Agreed! I'm very happy with the performance of The Judge EFL's.

Sure, they ain't cheap but they work and they last forever as long
as you take care of them. I want to get me another one that has
the E.T. function that has the LCD's that show the elapsed time.

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EconoCarl 6/13/12

I know thisis an old thread, I did an internet search for an "electronic finish line" and this thread pops up! I too would like to find an electronic finish line that just tells you which lane won. I don't care about times, my brain gets tired easily! Anybody out there figure out anything?

We briefly talked about it over here.

As I think about getting a four lane electronic finish line and knowing how much they cost, this looks more and more tempting.

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redlinederby 6/14/12
Site manager

Building your own with something like the Arduino is a whole new box of challenge and fun. I might be cheaper when it comes to dollars but not so when it comes to time investment. A DIY finish line is a project in itself that could take weeks/months to learn, understand, build and program. Don't get me wrong, it was a lot of fun learning about the electronics and seeing something that *almost* worked but it was exhausting (I have zero EE experience).

But when it comes to the Arduino, my mind started racing into things that I could do with it on a web/programming side. Sure, it can detect a winner and light a light, but then I started looking for a big picture that integrated results directly into my laptop and pulled from databases and all that fancy stuff. It's a typical problem for me...think big, get excited and then give up because rather than start with a teepee, I'm trying to build a mansion.

The finish line that comes with the Expert Drag Track is exactly what I want but I just want to be able to buy that separately. When I reviewed the track last year I asked guy if he could sell those alone or if that was in his plan and he basically said No, which is too bad.

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