Laser pointer based lap timer

[cdog4w]

I posted my progress over at ripper originally, but I think people here would be interested too.

I'm using this as a guide:
http://www.schumacher.clara.net/laptimer.htm

some software:
http://www.i4style.co.uk/vrs/
http://users.skynet.be/bk274532/pc_lap_cou...esentation.html

most recent update:
Sensor problem solved! Before everyone asks how it works now, I didn't get a chance to test the system out, track is currently in a pile (ie. not assembled) and we're going on vacation tonight so I won't get a chance to play until next week. There are also a few gremlins left that I need to work out, but I will detail those below.

Anyway, the issue was that the parallel port was setup in mode "ECP" in the bios of the laptop's motherboard. So I jump into the bios and the settings are "Normal", "Bi-directional", "ECP" and disabled. Once I set to normal and rebooted, sensors worked fine. Tested it out by running various objects thru the laser to simulate the flag on the car antenna and it seemed pretty solid using the Virtual Race System software. Counted up 40 some laps of varying length and it seemed to catch them all. Will have to test with a real car to see if it drops any of course.

Now on to the remaining problems:
1. Lasers dim after 2-5 min of use. I'm currently investigating why.
2. Lasers are difficult to aim using the wire mount setup. I plan on fixing this by using some leftover PVC pipe and mounting it to the gantry so the pointer is inside of it. Next I will insert screws at 6 and 9 o'clock on the pipe so that I can adjust the x and y axis of the aim independantly. At 1:30 I will put a piano wire spring that will push towards both of the screws to make sure the pointer adjusts with the screws properly. I'll see if I can find some cheap thumbscrews somewhere if it works.

[arfin]

Nice timer! That tile is gonna be a straight piece right :p. I really want to do this, just have to get a track started first.

[arch2b]

i see you've put alot of work into that :D

there are numerous tutorials out there for making your own laser pointer timing system. latency had one at one time on his site; http://www.latencyproject.com/

have fun on your vacation

[cdog4w]

Properly mounted the first laser! Adjustable separately on 2 axis' and firmly mounted to the frame. Also redid my laser solder job by pulling the board out of the mount in the head (which holds the focal lens) and soldering both connections directly to the chip. Before I had soldered 1 wire pretty unsuccessfully to the case of the pointer since that was how the pointer was wired stock. Next up is the actual track test with one laser/sensor.

I'll let the pics do the rest of the description:

[arfin]

When you solder the connections to the chip, did it fix the dimming problem?

[cdog4w]

Not entirely no, tho it is certainly a much better electrical connection than before. Soldering to aluminum just doesn't happen w/o special solder and I didn't have any :| I'm hoping that with the perfect aim this rig should afford, that it won't matter if it dims a little, it seemed enough to keep the sensor "on" when dimmed anyway. The shoo goo set overnight so I should be able to test once I get home tonight.

[cdog4w]

I will say that it requires that the pointer be aimed dead on into the phototransistor (tho its possible a LED mount with angled metal edges could make an easier target by reflecting the laser into the led if its not dead center), but the new aiming system seems to work and in my rough testing (2 2x2 tiles running back and forth past the lap timer), it didn't drop a single lap! I could see how it would be finicky due to aiming the laser, but if that portion stays on, it counted all laps accurately. I even bumped the framework and it didn't throw off the aim.

Next up is multiple car testing, but that means I need to build more of the new accurate aiming mounts.

[epoch1-43]

Cool; what is your investment in hardware and time so far approx? :)

[cdog4w]

Cost:
$9.00 - 4 laser pointers (price was for shipped off ebay)
$6.36 - 4x phototransistor @ $1.59 each
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=276-145
$2.20 - 10' PVC pipe + 2 T + 2 L joints (lowes)
$1.89 - male solder parallel port
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F003%5F006%5F000&product%5Fid=276%2D1547
$1.79 - parallel port cover
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F003%5F006%5F000&product%5Fid=276%2D1549
$free - cat5 cable (liberated from work spool)
$free - some 2mm screws for laser adjust
$free - some foam to provide centering force for laser so screws will adjust in both directions

total: $21.24 + tax on RS parts + labor

using a 5V power supply, can be powered from any 5V source
used a vice, hacksaw, soldering iron, drill

Time: maybe 5-10 hours, but mostly figuring out lasers and mounting. Soldering to aluminum w/o the proper solder is just a nogo, but I figured out more how the laser diode board works, so now its all board level and working fine. Laser aiming setup probably took the most time as I've gone through a few different ideas before settling on this. Gonna try some of these:
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F011%5F006%5F001%5F000&product%5Fid=276%2D080
to see if it aids in pickup by reflecting a slightly off laser into the phototransistor. Also want to go to a microplug setup so I can swap lasers/sensors in/out really easily. Need to stop by an electronics store to try to make those plugs LBRC uses.

[epoch1-43]

Cool, do you have pics of a car w/ flag installed?

[cdog4w]

Have a small video of me running back and forth, would that do? Not a real track setup but hey. You cant really see the flag, but if you pause and check around 11 sec in, you can see the laser above the car where it hits the flag (which is just a chunk of masking tape). The vroom sound effect is the lap timing software counting a lap. Also, the video is kinda dark, sorry.

http://www.putfile.com/media.php?n=laser_lap_timer_test

[epoch1-43]

Hehe, I had the video loading in another window and all of a sudden heard this sort of alarm sound and wondered what was going on! How does that antenna flag affect your ability to remove the body etc., or do you just tear it off each time?

[cdog4w]

So far I have only needed to take the body far off enough to change xtal, so up to the flag. Masking tape is cheap so you could easily pop it off and replace it. I think I'd get a perm marker and mark the spots on the antenna for the flag so that you could put it back on again w/o using the laser to judge where to put it. The guide I used suggested flag "templates", I assume something you hold next to the car to set the height for each car number.

[cdog4w]

pic of epoch w/ flag

EDIT: (forgot to rotate, sorry :)

[epoch1-43]

Cool; I assume the masking tape is light enough not to affect the CG?

[cdog4w]

Yea, doesn't roll any more than normal. Will try to figure out a way to maximize the software and build a decent track to video the system in action, but my cam only shoots 320x240. Might be a little tough to squeeze it all in frame and have the lap readout well.... readable.

[cdog4w]

I'm looking for a little help from those engineering/building oriented. I need a way to accurately aim the laser and mount it to one side. The pic called vicedup (attached on page 1) shows the current method, but its not as exact as I want. Its also a pain to build. I guess I could get more accurate by going to a 4 screw design to aim the laser, but it seems like I should be able to achieve the same results with 2 (but I can't get a good counter resistance on the other side of the laser...).

Since I might soon be getting a real RCP track and won't have to deal with my ghetto-tastic track, I will be happy to start really using the lap timer to start profiling my driving and to race with friends.

Any input will be appreciated!

[cdog4w]

Got some RCP track and the current design of the lap timer just wouldn't do. The lanes are wider so I'd need a longer cross piece. Instead of doing that (a bit unwieldy too), I chopped off all but the lasers and the sensors and mounted the T joint to a shelf from an ikea book case (cd/dvd shelving). Much more compact!

http://cstanleyw4.home.comcast.net/rc/lap_timer_base.jpg

[cdog4w]

1 car version: FINISHED!!! One pic shows the car flag breaking the beam, the other shows the beam hitting the sensor. Ran a 50 lap race and it didn't drop a single lap. You can also see the lap timer software up on the laptop in the background, I'm using lap timer 2000 and its pretty nice so far. It could do with a bit more configurability etc. but not bad for free :)

http://img112.imageshack.us/img112/1016/laptimer09vy.jpg

http://img116.imageshack.us/img116/1807/laptimer12fp.jpg

[arfin]

Sweet setup! Nice track ... do you feel the RCP track is worth it? I might look into it. Now all you need is some competition. So in the end how much did the lap system cost you?

[cdog4w]

Well, I got the RCP as a bday/xmas gift from my wife. I will say this, its very expensive, but if you can get over the money, the track is simply amazing. Very high quality stuff, very easy to setup and breakdown. I setup the track in ~20 min (the borders were already on from first time up), breakdown is like 10 min. You might be able to make a nice setup for cheaper, but RCP also combines with other RCP with no fuss. This gets to be a nice feature if you can talk a bud into buying one for himself, then you have a 2x size track when the 2 of you get together.

Anyway, final cost on lap timer was ~$25. I did a bit of scrounging, but not too much. You can probably save in some areas, but not more than $5 unless you happen to have laser pointers and phototransistors handy :) You might be able to save more if you have a local electronics store that is cheaper than RS?

If you want any details or help on building just let me know and I'll try to help.

[teambluegroove]

yes i need some help, here is where i'm at i have soldered 4 lasers to a 4.5v power source they are working fine and i soldered one photo transister to the connecting wires that connects to a 9 pin serial port then to a serial to a usb converter i'm not sure on the wiring to the 9 pin serial port i followed the wiring diagram from here
http://72.14.207.104/search?q=cache:e-PjiwPkFcMJ:www.hoslotcarracing.com/LapCounter.html+vrs+lap+&hl=en&gl=ca&ct=clnk&cd=8&client=firefox-a
but it says its for track mate i was goning to run lap timer soft ware like you suggested how should i wire it,do you a wiring diagram for a 9 pin
my lap top doesn't have a db25 port what should i do
and will my computer recognize a 9 pin serial port - to usb adaptor being pluged in to a usb port and if not how would i configure it thanks, for any help you can offer please dumb it down for me as computers aren't my area of expertise

[cdog4w]

So you don't have either the gameport or the parallel port? I'm not sure if the Serial to USB converter will work, but go to http://www.gregorybraun.com/index.html and email the author, he should be able to tell you yes/no pretty quickly. I'd say if the converter emulated a serial port so that lap timer 2000 saw a serial port, then it'd probably work, otherwise, probably not. Good luck!

[LBRC]

Found an old laser pointer so I scrounged up an old printer cable for the connecter and decided to see if I could make a single car version with them for fun this weekend, it works and all for a grand total of $1.59 + tax :cool: the one part I didn’t have was the photo transistor.

Alignment was simple since it’s only for a single car, I took the laser diode and driver module completely out of the pointer and inserted them into a ¼” hole drilled into one side of my old track and then drilled the small photo diode hole where the beam shown on the other side, no flags needed since it’s just a single car version, as a car body goes by it breaks the beam nicely. So far I've tried a Epoch, Mini-Z, and ZZSE and all have worked without a glitch.

One thing I really like is that since the laser and diode are imbedded in the foam wall of the track with micro connectors you can hardly tell thay are there at all when unplugged.

[cdog4w]

Laser lap timer got a track test last night with 2 cars, failed miserably. Two main issues, I need a better way to align them and two, I need modules that don't overheat and dim. I'm currently using cheap laser pointer modules that I pulled out of the case. With just one I am able to get consistent races, usually two 50 lap races before the modules dim and poop out, but last night they were showing their frail nature. So time to replace the laser side!

http://cgi.ebay.com/650nm-5mW-laser-module-3VDC-full-brass-case-650-nm_W0QQitemZ110050895062QQihZ001QQcategoryZ53141QQ cmdZViewItem

Picked up 3 of those after asking the seller if they would be able to hold up to long term constant on time when using a regulated power supply and he said that it should be fine and not overheat.

Anyone have a suggestion on how to mount them? I got the full brass case just to ensure that they'll stand up to some abuse and hopefully to also make them easier to mount.

My other thought is to try using these (http://www.radioshack.com/product/index.jsp?productId=2062559&cp=2032058.2032233.2032297&parentPage=family) to mount the phototransistors as a focal mechanism to lessen the need to hit them dead on. More fault tolerant. Hopefully the new lasers will also make it easier.

[cdog4w]

got the lasers, but haven't had a chance to test yet.

[PaulBoth]

Hi,

I've built a few Laser based lap timing bridges for myself as well as other people before. A couple of things that I have learned:

1.) With the cheap laser pointers, limit there input voltage to 3.5V. By doing this they will never fade out. I've had some even operate as low as 2.8V. I typically use a 12V power pack. Then to limit the lasers I use some 7805's (usually one for every 4 lasers) which gets me to 5V +/-. So to get the voltage even lower, I use some 1watt resistor's of the appropriate value. Ultimately, the lower the module will run, the better in terms of less heat...

2.) The laser needs to be adjustable (completely) in 2 different Axis'. I typically accomplish this by making a triangular shaped plate and then using JBWeld to attach the laser diode module to the plate. Then to provide resistance to the three screws (one in each corner of the triangle) I use fuel tubing that is about .125" longer than the exposed threads. This keeps the laser pointed where I need it and takes any shock applied to the system.

3.) Add-on cards typically are better made - thus allowing you more lanes to work from (8 rather than just 5). However, with that being said, you need to be running Windows 98SE or older in order to apply legacy port addresses.

Your project looks good so far... if you have any questions, let me know as I may have run into the same problem myself.

PB

[cdog4w]

The lasers I got are spec'd to 5V source so I can use a 7805 w/o any extra bits. They also sell 3.5V lasers, but I figured its easier to source 5V. Not sure what they'll need cooling wise, but I was assured that they would be able to be run constantly on indefinitely with proper cooling. Worse comes to worse I just drop a fan on the assembly.

I'm really interested in your mount. Sounds like it would be able to adjust left to right pretty easily, but I'm not positive on the up/down. Post a pic?

Thanks for all the tips, always good to get more info!