Electronics are the black magic voodoo child of some evil sorceress born to confuse me, and based on the comments from many people while I was searching for a way to time a race, I believe quite a few of them feel the same way I do. Looking through post after post of DIY articles with computer control boards, a spaghetti bowl of wires, and computer programming language made my head spin. Of course every single one of them says it's not that bad, but I would like to respectfully disagree. Now, I would love to just buy one and be done with it, and I would too, if I could find one that would just hook up and work. The only one I've seen that did that was the one 3DBotMaker was selling, but I missed out on those, and apparently there aren't any more. So, while contemplating throwing away a big chunk of money on a pile of electronics that I knew I'd never be able to put together and make work, a thought hit me. Why not make it mechanical?
So, here was the thought. Instead of using light beams to trigger the timers, why not just use a mechanical switch? So, I bought a bag of momentary Switches $7, a spool of wire $7.50, and a cheap stopwatch $8. And then I set out for a few frustrating evenings of failure.
1. Wire up the stopwatch - This wasn't that big of a deal. There are articles on here about a DIY timer that shows you how to wire up the stopwatch. All I did was pull the housing apart, and solder a wire to each side of the switch. Then, drill a hold in the casing so you have a place to run the wires through.
2. Make the watch start - Again, this was very easy. I'll tie the two wires to a switch and mount it to the track so that the starting gate activates the switch.
3.Make the watch stop - Aha! So here is where I ran into the problem. The switches are too stiff, and their throw is too long. I tried various ways of mounting the switch, under the track, through the track, on the sidewall of the track, and none of it worked. The cars don’t have enough weight to trip the switches, so mounting underneath is a no go. I tried it with just the switch, then with a hinged ramp the car would roll on to try and give it some leverage against the switch, but there just isn’t enough weight in the cars to do it. Next I tried mounting the switch on the side of the track, hoping the car’s momentum would help it trip the switch, but there is too much throw in the switch and it’s too stiff still. Some cars would be wide enough to trip it, but others wouldn't, and none of them really had the power to do it anyways. I tried making my own easier to move switchs, but that was an epic fail, and that led me to my current iteration.
I made a swinging gate, here out of a popsicle stick and a duct tape hinge. I did have to bend the arm on the switch to get the movement correct. The added length of movement from the popsicle stick makes the switch activate with any car, and there is a leverage advantage that makes it easier to push the switch, and it actually works, but not perfectly, and so far only in prototyped practice. Because of the hinged gate, cars of different shapes will have slight advantages over others. I can actually live with that, but the switch is still fairly hard to push. The cars do trip it, but they have to be going at a decent speed, and some of my cars just manage to crawl across the line. So, this is where I need the help of the electronic wizards. Is there a better switch or a better way? Heck if you are a non wizard, can you think of a better way to activate the switch? I think this would be great way for all of us non-electronically minded people to be able to cheaply and easily time races, if I can just get it to work.