Over the Christmas break, I finally got around to building a photocell laptimer. I thought I'd like to try to give something back to this forum and share my results..


http://lh5.google.com/roffutt/R4cD31faG7I/AAAAAAAAAOg/4xJZihEFS30/s800/1.jpg (http://picasaweb.google.com/roffutt/TimerBuild/photo#5154092556335324082)

I started with the idea that I wanted to build a laptimer using the joystick port, because I had an old joystick (actually a gamepad) that was no longer needed and I could salvage the cable from it. While rummaging through my junk box, I found a couple of old mice (really old ones with a rollerball, newer mice are optical) one had a 9db serial cable.. so like most people of this forum, I thought I would over build my laptimer with the option to use a joystick or serial connector. Also thought that it might be cool to have a double counter system to double check against mis-counts. I later, learned that the software I'm using (Gregory Braun's Lap Timer 2000 v6.1 (http://www.gregorybraun.com/LAPTIMER.ZIP) ) does not support using 2 counting systems at the same time, so I held off on building the serial interface.

http://lh6.google.com/roffutt/R4cD3FfaG5I/AAAAAAAAAOQ/nBZR4ncu1vU/s800/7.jpg
(http://picasaweb.google.com/roffutt/TimerBuild/photo#5154092543450422162)

I bought the Radio shack components recommend on Mr. Braun's website, as well as a project box and a breadboard. I decided I wanted to connect to the track using standard phone cable using the RJ11 connectors. I felt phone cable was perfect being only four wires (2 for each lane), and it comes pretty flat. Not to mention it's cheap! I hit a bit of a snag when I learned radio shack does not sell a female rj11 phone connector. I originally thought I could buy a phone extension cord and cut it, giving me a female and male cord to work with... but, oddly enough.. I could not seem to find a single line extension cord? All came with a double or triple split. But, I did find a 5 port split cord, that by the looks of it I could take apart and reuse the female ports out of it.

http://lh3.google.com/roffutt/R4cD3VfaG6I/AAAAAAAAAOY/x95QbkoA5a8/s800/6.jpg (http://picasaweb.google.com/roffutt/TimerBuild/photo#5154092547745389474)

The photo-cell collectors sold by radio shack are pretty large.. I originally thought I might have to grind down to get them to fit under a tomy track piece. (Not even sure if that they would work if I did that?) But, After taking apart the old serial mouse I realized that mouse uses a collector and emitter to track the x & y axis of the mouse ball. I disassembled another old mouse with a scroll wheel, it had a total of three collectors & IR emitters. These collectors are much smaller and lower profile then the ones from radio shack.. so, I decided to use these instead. I have not used the emitters.. but I wonder it would be possible to use these smaller components to build a lap timer triggered by the guide pin. I figured it could probably work pretty good for slower pan-cake cars.. but I play with mostly magnet cars. (I might get bored and try this out someday.. writing this has me curious again.)

http://lh3.google.com/roffutt/R4cD2VfaG2I/AAAAAAAAAN4/u-ML4rjC-sM/s800/4.jpg (http://picasaweb.google.com/roffutt/TimerBuild/photo#5154092530565520226)

Top: The extra female rj11 plugs.
Left: Collector comparisons mouse vs radio shack bought one. (The penny is for size reference)
Right: Emitters removed from the mice.

http://lh3.google.com/roffutt/R4cCwVfaG1I/AAAAAAAAAN0/KaEeKIkh_0Q/s800/2.jpg (http://picasaweb.google.com/roffutt/TimerBuild/photo#5154091327974677330)

The smaller size made a perfectly snug fit in between the slot and rail of the under side of the tomy track. I love hot glue! ;) Hard to see in this picture, but I used the dremel to drill a hole so the two tracks can sit flush together and grinded a notches for the wires to lay flatter. I don't currently have a lamp bridge.. I just used an adjustable desk lap that could hover over the photo collectors on the track.

I don't currently have a permanent setup... So, for now I'm content with just laying out a temporary track in the one of our living rooms for a couple of days. I have four kids, ages range from 2 1/2 to 12. I hooked the lap timer to our HTPC (Home Theater Computer) so the lap times and racing results were displayed on the 55" big screen TV. We all had a blast.. My older two daughters really got into who could post the fastest lap time! They are now seriously infected with the slotcar racing bug!

Link to all photos from this project (http://picasaweb.google.com/roffutt/TimerBuild)

-roffutt

Now THAT is cool...
To bad the additional pictures are blocked at work..... : (
But I will look when I get home...

Now THAT is cool...
To bad the additional pictures are blocked at work..... : (
But I will look when I get home...

Thanks. Hmm.. that is wierd, they are all hosting on google? I would think they would all or none would be blocked? Although I think there are only extra 2 pictures missing.. the disassembly of the mouse.

Nice job roffutt.I'm curious as how reliable your setup is.I bought Greg's LapTimer 2000 system and have had nothing but problems with it.I'm not sure if it's his software program or what.It works some of the time and thats the problem.It will count up to about 20 laps and then just stop counting laps all together.I've talked to Greg on the phone about my issues and he just kinda blew me off.Not real happy with him at the moment.Anyway nice job with your work-keep it up!!! :)

RiderZ, What a bummer.. sorry to hear you cannot get it working. Are you using a serial, parallel (printer port), or a joystick port? Are you using photocells or reed switches? If you are using photocells.. is the light source inf-red?

-roffutt

When I was talking to one of the guys in our local group, he suggested that shielded wire must be used between the timing devices and the PC, not sure if that's your issue, but it may be worth checking.

I just bought some stuff today for testing timing on my routed test track :)

Cheers

Richard

Hey guys-i'm using a joystick adaptor that plugs into a USB port.Also using photocells.It works-just not reliably.I still get too many missed lap counts.Cant hardly run a race with four guys without a reliable system.Its just too hard to keep track.Yesterday i ordered some stuff from RadioShack.Namely the matched set of IR emittors & sensors.Also bought some resistors and other goodies.I was in touch with SwamperGene all weekend through PM's trying different things.He suggested to get the matched pairs of the RS equipment.Fingers crossed!!! :) As far as light source goes.I had the four IR led's received from Greg Braun mounted in the bridge.Worked -not reliably-so now i have six 12V incadescent mini bulbs wired in running off two 12V powerpacks.Still works just not reliably. :rolleyes:
The sensor to computer cable is sheided,plus its only 8 ft. long so i dont really think thats the problem. :)

Don't need shielded cables, all we're doing is interfacing some very basic analog switches to the PC.

Don't need shielded cables, all we're doing is interfacing some very basic analog switches to the PC.

Damn - you mean I could've bought cheaper cables?? :(

Oh well ... ! Sorry for the mis-information.

Richard

RiderZ, Still seems odd that it works fine for about 20 minutes.. and then quits working. Sounds like maybe your laptop is going into a hibernate or reduced power mode after 20 minutes of inactivity? A screen saver or some other background process (Virus scanner, files indexing service, etc..) might be taxing the processor. I know the newer laptops drop their processor/bus speed down after so many minutes of inactivity or when full processing power is not needed. They can also turn off the harddisk to conserve power as well. I'd double check your laptop manual.

If your running XP, on the 'Screen Saver' tab of the Display Properties window there is a button to open the power consumption options. I'd check what power scheme it is set to, and try setting it to "Always On".

-roffutt

Damn - you mean I could've bought cheaper cables?? :(

Oh well ... ! Sorry for the mis-information.

Richard

I've got like a 50' dollar store phone cable going from my LPT port to my sensors (ok, it was qiuck n dirty, but works fine).

:freak:

Been there done that roffutt! I like to think of myself as computer savy so i do know my way around a computer.As i stated earlier i have just a guess at 20 hrs. of tinkering around with this trying different stuff to get it to operate consistently.I will try the new sensors and if that dont work i will DEMAND a refund from Mr. Greg Braun!!!!!!!!!!!! :mad:

Well, I wired up my test routed track tonight, and am having similar problems. If I run my cars slowly over the reeds I get a signal and a lap is triggered, but if the cars are running, they sometimes trigger, an sometimes don't (and usually when the cars are running slower, it's more likely to trigger). But running at the closest I can get to top speed on this small track, don't seem to trigger at all.

I've got about 2mm of MDF between the reeds and the track above - does this need to be taken down further??

Thanks

Richard

Frustrating aint it Richard.I dont know alot about the reed switches but i believe they are triggered by magnatism.Your track maybe too thick where you have your reeds installed.

This morning my matched IR emitters & sensors came in from RS.I need to know if there is a positive & negative side to the emitters & sensors? Also is there a positive & negative side to the wires from the junction box to the IR sensors? Also what resistors from the pics below would work best with the IR emitters running off 12V 200mAh power packs? :confused:

Rider, you want the 1/2 watt 470k resistors for a 3.3v input on the LED. Your IR senders should be 20 mA current, but check the back of the package. Here is a calculator for your needs:

http://led.linear1.org/1led.wiz?VS=12;VF=3.3;ID=20

Yes LED's are polarized- it shouldn't matter in the sensor circuit but you will assign pin numbers to those anyway.

http://www.theledlight.com/img-tech/led_dwg.jpg

With 470K they probably won't light.

You have to remember that the sensors are each dropping voltage in the circuit. These particular sensors can "consume" 2V each (vf), so with a 12V source and the sensors in series 4V has to be dissipated. At the rated 40mA current, you'd need a 100 ohm 1/4W resistor.

Just as this calculator shows. (http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm)

Now that's pushing them to the max rating. You could go a little higher in resistance, but if you don't drop the supply voltage plan on lots of heat.

Gene that chart you linked shows a forward voltage requirement of 2 volts for those LED's and is for running them in series. Most IR's and high output LED's have a forward voltage of 3.3 volts and 20 mA forward current. You don't want to skimp on power with the IR senders. I ran one 470 ohm resistor on the + side for each LED on my tower.

Rider, check the specs on the package- I'm pretty sure those RS senders want 3.3 volts and a higher forward current than standard LED's. ;)

I'll look at my tower when I get home... ;)

Heres the specs on the back of the package! This should help you electronics wizzards to get me going with the wiring.

Emitter: (tinted package)-Maximun Voltage & Currents

reverse voltage-5V
continuous forward current-150mA
forward voltage-1.3V typ. 1.7V max.
radiant power output-13-15 mW
wavelength at peak emission-950nm

Rider, you want the 1/2 watt 470k resistors



470 ohm I don't doubt ;)

I spec'd the senders on the RS website, there they list 'em a 2V, close to what the package says.

Gene i just finished up wiring in the new emitters & sensors and i use the 470 ohm 1/2 watt resistors.I checked them with my digi camera and the do "light".I need to pick up some hot-melt glue for my gun so i can glue the sensors into the track openings.I'll have to wait till tomarrow to see if this setup works reliably!

Riderz for testing you might want to use a less permanent method, maybe some of that picture hanging putty if you might have some laying around.

For the record, here's a drawing of the last setup I did, this is a year old now, in a commercial environment, and still works flawlessly. The sensors are simply pushed into the 3/16" holes from under the table and fit nice and snug, no glue needed.

http://i7.tinypic.com/6nvhjpf.gif

Thanks Gene-you are probably right.I could go sparingly on the glue till i figure out if its going to work or not! :rolleyes:

A little dab'll do ya :thumbsup:

Seems as though the old emitters & sensors supplied to me from Greg Braun with the LT 2000 system were the culprit of my problems.After installing the new ones bought from RadioShack i ran a ton of laps in each lane without any missed lap counts!!!!!! :) Finally solved the problem!!!!!! :woohoo:

Rider z it looks like you have a resistor over each IR led. The calculator only shows one in series wiyhall 4. I am about to solder mine up with one but before I do just thought I would ask about this. I am using 4 of the RS IR Led #276-143 with a forward voltage of 1.2,forward current of 100mA, a single 48 ohm 1 watt resistor powered by a 9 volt wall wart.

Rider z it looks like you have a resistor over each IR led. The calculator only shows one in series wiyhall 4. I am about to solder mine up with one but before I do just thought I would ask about this. I am using 4 of the RS IR Led #276-143 with a forward voltage of 1.2,forward current of 100mA, a single 48 ohm 1 watt resistor powered by a 9 volt wall wart.


Good question aelancaster-i was under the assumption you needed one resistor for each led.Is this correct???Maybe you do maybe you dont.Hopefully SwamperGene will chime in on this question-he'll know!!! :p

Thanks for the quick reply I hate doing things twice. I agree, hopefully Swampergene will know the answer.
Andy

RiderZ good to hear it's working...fingers are crossed.

Andy, RiderZ has them wired in parallel, the calculator you are using is likely in series. I've heard arguments on each, and used to do mine in series, now I do them in parallel which allows a lower voltage supply to start with, just gotta make sure it has sufficient mA. Personally I just like the fact that it more or less keeps each LED isolated.

Side note...regardless of what the calc says, I'd temporarily put in a 100-150 ohm first on that setup, see if it works and check the wires for heat. If they are too dim, drop 50 ohms at a time but keep an eye on how hot the wires get.

Gene the wall wart is a RS #273-1667 that says 3-12 volt 800mA. Are you familiar with the RS IR leds I am using? Can you direct to a site that would give me a diagram for the parallel circuit using 4 leds and 4 resistors. I can't drop my resistor value by 50 ohms as I am starting out with 1 rated at 47 ohms. Thanks for the help.
Andy

I have to thank SwamperGene for all his time & effort in helping me solve my issue with LapTimer 2000.As i said thanks a ton Gene!!! Yes my fingers AND toes are crossed that this solved my problem!!! :) :) :) :)

My problems with the lap counter related more to getting the settings in Lap Timer 2000 right and as well as doing a clean install of the OS. Been rock solid for about 6 mos. now. Keep tweaking it and you'll get it right.

Andy I've never had any luck with those LED's but at 12V in parallel you'd want 470 ohms on each, the RS site lists them at 1.2V 29mA. (?)

As to testing, I meant starting with 150 ohms then dropping. Simply put, you could chain three 47 ohm resistors, if light output is too low take one out, if still too low take 2nd one out....just keep feeling the wire for heat (careful tho' it could get real hot).
RiderZ, anytime :dude:

Thanks Gene, any chance of getting a diagram of what you are describing?
Andy

I'll see what I can do tomorrow. :)

Don't need shielded cables, all we're doing is interfacing some very basic analog switches to the PC.

You were right - I replaced mine with telephone cable and it works much better!

Cheers

Richard

Ok roffutt-sorry to highjack your thread.Now that everything "seems" to be working with mine.Hows is your system working for you??? :thumbsup:

RiderZ,

No problem.. I don't feel it was hijacked. ;) Just lots of good information.. I also learned a bit along the way. Glad to see it is working good for you now. I've not had any problems with mine, but still need to build a light gate. I've been more curious about see if the smaller components I'm using, will work in a completely under track system.. Might have time this weekend to build it and test it out. I'm also thinking about writing my own software for lap counting.. as I have a few ideas I'd like to add.

-roffutt

Well, I wired up my test routed track tonight, and am having similar problems. If I run my cars slowly over the reeds I get a signal and a lap is triggered, but if the cars are running, they sometimes trigger, an sometimes don't (and usually when the cars are running slower, it's more likely to trigger). But running at the closest I can get to top speed on this small track, don't seem to trigger at all.

I've got about 2mm of MDF between the reeds and the track above - does this need to be taken down further??

Thanks

Richard

For best results the reed switches should be under the track between the slt and the rail. Oopops routed track. Your reeds should be inside the rail on the slot side. If they are too big you need to get smaller reed switches

Roger Corrie

Well thought it was not working since I could not see any light thru the digital camera. So just for kicks I put the bridge back together,fired up the computer and she works like a champ. No missed laps or false counts. :woohoo: Thanks RiderZ and SwamperGene. Could not have done it without you. :thumbsup:
Andy

Where here to help and get help from all the great info providers on this great hobbytalk board!!!! :thumbsup:

Your reeds should be inside the rail on the slot side. If they are too big you need to get smaller reed switches

Roger Corrie

Thanks Roger - if changing the wiring didn't help, my next plan was to route a slot in the top of the track, as you've suggested. Fortunately this is my test track, so I'm not too perturbed if it's not working 100%

The reeds themselves are called "ultra-micro mini reed switches" are are around 1.8mm diameter and about 1cm length. I've got some pics to post, but I'll do that in our local forum here (in case anyone is interested):

http://neophytte.mine.nu/forum/forum.pl?fid=05&topic_id=1162044390&page=10

And thanks to SwamperGene who made me doubt my initial setup enough to re-wire :thumbsup:

Cheers

Richard

A lot of good info here as I am doing the same thing with Lap Timer 2000.
I about have all the stuff I need. The track power relay Shown on Brahms
site,,I can't find one like it at Radio Shack.

woodman are ya any good a building 'lectronical stuff? You can build a compatible one from RS parts:

http://images.yuku.com/image/pjpeg/12e1554f76fbca982b24a744c628816a3f7bdff.jpg

No man I am a cabinet maker......I need explicit simple diagrams (not schematics).


But have built a 12' wood runabout with a grafted in hull from a jetski (kawasaki 650)
http://s147.photobucket.com/albums/r302/scrawford_photos/
Go to my photobucket and see vidio of the boat and go to sub albums to see the build of that and other boats.

Electronics no.........
Nice neat photo though you must be an electronics wizard..........

Also need a power supply,all I have is a deep cycle batery charger.

Gene,

I ended up buying the relay that Greg mentions at his site, I think even from the same source he mentioned. I tried to find one similar locally, but struck out.

What is the Radio Shack equal?

BTW - that box looks so dang good. I'm rebuilding mine on my next track.

Thanks, Scaf :)

As far as I know, Radio Shack does not have a similar component. Basically, all that's in the box are a couple transistors being used as a relay driver and a RS PCB mounted 10A relay. If RS did stock low power high capacity relays like that, I'd be all over 'em.

Gene, I stumbled across this relay the other day and wondered if it would be a cheaper alternative?

http://www.allelectronics.com/cgi-bin/item/SRLY-18/500/18_AMP_SOLID-STATE_RELAY,_3-15VDC_CONTROL_.html

The control voltage is 3-15vdc, but the switching is rated for AC (18amps @ 240v), I don't understand why it would not work for switching DC as well?

-roffutt

I'd say not roffutt, if you look at the manufacturer's site, they list separate models for AC or DC outputs, and they are based on different technologies internally.