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Old 2006.02.15, 10:04 AM   #1
Blackranger3d
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Help Building a Lap Counter

Purpose: To build a cheap (relative to the $600 counters people are using) reliable lap timer / counter.

Application: My race track in my basement.

Option 1 – Wired to Keyboard
Option 2 – Wired direct to LPT port
Option 3 – Use 4 – 6 TOMY LAP COUNTER DIGITAL TIMER

Generic Apparatus:
- 6+ laser source (laser pointers)
- 6+ light detectors (phototransistors)
- PC Software to record laps and times (there are lots out there, this is not a problem)
- wood / plastic etc to build gantry
- flags for car antennas


Option 1.
Option Specific Apparatus
- keyboard
- PC


Method:
Wire phototransistors to a key board so that when their source of light is broken a keystroke is registered on the keyboard. The PC Race Software will then take this keystroke and record a lap. For most of the programs I have seen a keystroke from 1 - 10 will register a lap in the corresponding lanes (i.e. 1- 10). Each phototransistor will be wired in at increasing height along the gantry. Each car will have a flag on its antenna, the height of which corresponds to the sensor.

Pro
Will allow race to be recorded on laptop, with sound effects etc.
Lots of wiring (I like building this stuff)

Con
Lots of wiring (lots to go wrong)
Have to figure out how to trigger keyboard

Option 2
Option Specific Apparatus
- Keyboard
- PC
- DB25 plug

Same as above, except wire direct to PC though DB25 plug (LPT port).
Pro
Simple

Con
I cannot get it to work. I don’t have an LPT port on my desktop PC, and I have not been able to figure out how to turn the LPT on my laptop on. I assume the laptop port works since the laptop is about 2 months old.


Option 3
4 –6 x TOMY LAP COUNTER DIGITAL TIMER HO AND ALL SLOT+RC CARS

Take 6 of these brake them apart and then mount them in wood or plastic at every increasing height. Follow this tutorial to extend the range. Then put flags on the cars and race.

Pro
Simple.
Electronics already done.

Cons
Too easy.
Display too small, no cool sound effects. Cannot print out results.


My dream would be to use the core system. But good god almighty I am not paying $600USD + for it.

So I guess my main questions are.

What are you thoughts on the options?
How do I wire a phototransistor to trigger a keyboard keystroke?
Is there a way to wire direct to a keyboard port (I don’t have a joystick port on my desktop or my pc)?
How do I turn on my IBM R51 LPT port?
Any other suggests for counters?

I have posted this in a few forums to see if I can get some good advise.

Thanks for reading.
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Old 2006.02.15, 10:30 AM   #2
Spoon
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I think option 1 may be your best bet. The wiring would be pretty easy to test and debug. Once you got one working, the rest should be identical.

Without actually trying it, here are my thoughts.

1. You are going to need to dismantle a keyboard and see how the keys are actually triggered. I suspect it's some sort of electronic contact (i.e. a switch)

2. You are going to have to find an IC (integrated Circuit) that can be triggered by the voltage change (or resistance change) of the phototransistors.

3. You are going to have to figure out how to make that IC activate the appropirate switch on the keyboard. This is where you would wire directly into the keyboard. From there, the keyboard and computer could figure out which switch you depressed, you don't have to deal with that "translation".

I don't know off hand the characteristics of a phototransistor. I am sure you can find a datasheet or do a simple test. I think it's actually a voltage change...some google searching should reveal some answers.

It sounds like a fun project. If I come up with any ideas or find anything specific, I'll let you know.


One more thought...can you buy an LPT card for your desktop? I think I have seen timing systems that are wired to an LPT port. If you can get a card, that may be easier than trying to hack a keyboard and make a control circuit.
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Old 2006.02.15, 10:48 AM   #3
Blackranger3d
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Thanks, this is the best advice I have seen so far.

I don't really want to involve my desktop since it is in my office which is now where near my track.

I am hoping to connect the lap counter to my Laptop throught either the LPT port (can not get it to work so far) or through an external keyboard.
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Old 2006.02.15, 10:51 AM   #4
Blackranger3d
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I have found this, http://aticatac.altervista.org/schem...e_keyboard.pdf I don't fully understand it.

But my first thought is that I can build a circut board to just out put keystrokes 1 - 10.

I then still have to figure out how to get the transistors to activate the keystrokes.
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Old 2006.02.15, 10:58 AM   #5
rmfroyd
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My experience.

I just built a laptimer using the following program

:http://www.gregorybraun.com/LapTimer.html

I used 4 lasers and a printer cable to hook up to a laptop. If you look around the sight it will show you how to wire your ir recievers to a printer cable so you can hook it up to your computer.

It works very well, however you need bright lasers. I searched the internet and many people recommend the cheap keychain lasers that you can buy at dollar stores. These did not work for me. I ended up have to puchase lasers that are used for laser sights for guns from Walmart.($20 each) Once I installed those it works real well. If you have any questions let me know.
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Old 2006.02.15, 11:37 AM   #6
Spoon
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Quote:
Originally Posted by Blackranger3d
I have found this, http://aticatac.altervista.org/schem...e_keyboard.pdf I don't fully understand it.

But my first thought is that I can build a circut board to just out put keystrokes 1 - 10.

I then still have to figure out how to get the transistors to activate the keystrokes.
Could you attach the pdf, I can't get to the link.

The problem with outputting the keystrokes without the keyboard, is that you don't know what a "1" looks like to the computer. It's a possibbility, but it's another bit of research required.
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Old 2006.02.15, 02:14 PM   #7
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Nevermind I can get to the pdf.

The more I think about this the more I think it can be done.

First, the schematic. It's basically showing you which combination of control wires generates which keystroke. It's sort of like a telephone. For a basic keypad there are 3 columns and 4 rows. Each row and each column have a wire associated with them. When you press the number 1 current travels from the wire at row 1 to the column at row 1 so the phone knows what number you are pressing. I don't know exactly if it works that way, but that's the general idea.

That keyboard schematic is just showing you which control wires have to intersect to get that particular key.

So I think what you are going to need is some sort of transistor circuit. It's been a while since I have done any circuit design, so I can't give you specifics.

Do some transistor research. You will find that a transistor is basically a switch with three inputs. Actually one input, one output and one control.

For you timer you would connect the input and output of the transistor to the intersecting wires. For example, to control the "1" keystroke on that schematic, you connect A11 to one end of the transistor and A8 to the other. Your phototransistor would control the switch.

You will have to figure out the specifics to control the transistor but I am sure there are circuit diagrams out there.
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Old 2006.02.15, 02:19 PM   #8
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http://www.hiviz.com/tools/triggers/makeown.htm

Check that out for a diagram that's similar to what you are trying to do. It triggers a buzzer when the light is broken.
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Old 2006.02.15, 02:34 PM   #9
rmfroyd
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Lap Counter

Just my 2 cents worth. The lap counter I made that I mentioned before cost about $150, a large portion of that being the lasers. What you guys are proposing with the keyboard is cool and would be a fun project, but there are easier ways to go about doing it. Almost all lap counting program on the web usually have schematics for wiring inputs to your computer,(printer ports, joystick ports, etc), that aren't complicated and require basic soldering skills, most don't need transistors, or resistors. If you are doing it for fun go for it, but there are easier ways out there.
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Old 2006.02.15, 02:43 PM   #10
Blackranger3d
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Thanks rmfroyd. But in my first post I said this.

>>>>>
I cannot get it to work. I don’t have an [b[LPT[/b] port on my desktop PC, and I have not been able to figure out how to turn the LPT on my laptop on. I assume the laptop port works since the laptop is about 2 months old."
>>>>>>
I want this counter to be usable on my laptop (which has LPT issues).

All the diagrams that I have seen are for LPT (does not work on my laptop) or joystick ports (don't have one on my laptop).

So I figured the best option would be a keyboard based solution.
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Old 2006.02.15, 02:55 PM   #11
Blackranger3d
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Spoon, thanks for the help you have set me in the right direction.

I have posted a question in a DIY electroinc forum. I love the internet, there isn't anything that you cannot learn if you try.

http://www.electro-tech-online.com/v...=127105#127105
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Old 2006.02.15, 03:38 PM   #12
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Quote:
Originally Posted by Blackranger3d
Con
I cannot get it to work. I don’t have an LPT port on my desktop PC, and I have not been able to figure out how to turn the LPT on my laptop on. I assume the laptop port works since the laptop is about 2 months old.
I had the same issue, but I figured it out: 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.

Give it a shot, its very simple and works pretty well. The main issue is the quality of laser, I'm using the cheap laser pointers (4 for $9 shipped off ebay), but they dim after a few minutes. I might have to try the gun lasersight idea... at least for my primary counter. You can see my build thread here:
http://www.epoch1-43.com/forums/show...?p=758#post758
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Old 2006.02.15, 03:43 PM   #13
Blackranger3d
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Thanks for the BIOS tip. I didn't even think about looking in there.


Quote:
I'm using the cheap laser pointers (4 for $9 shipped off ebay), but they dim after a few minutes. I might have to try the gun lasersight idea...
Are you running off battery, or AC adaptor?
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Old 2006.02.15, 04:15 PM   #14
cdog4w
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Quote:
Originally Posted by Blackranger3d
Are you running off battery, or AC adaptor?
Tried both. Even my regulated PSU.
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Old 2006.02.16, 01:15 AM   #15
cdog4w
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Put my RCP back up (it hogs pretty much the entire living room when up, and in an apartment, thats hard to deal with for long), and finished adapting my lap timer. Works wonderfully. The dimming didn't seem to be an issue, I ran 2 50 lap trials w/o dropping a single lap powering the laser on 3AAA. Using lap timer 2000. I still need to fix up the rest of the lasers (you can see them dangling), but once thats done I can run up to 4 cars (with the current rig).

pic

pic2
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