Electronic circuits & projects forum - Need help with electronic circuits & projects?

[DROz]

I am building a slot car lap counter as a companion to my own design of a grand prix starting light sequence tower.

I want to keep track of which lane is leading, which lane is in second place, and which lane is third (podium finishers).

I can't think of how you can take four inputs, increment each one as the cars cross the line, rank the totals of each lane, and then display the corresponding lane number on a designated readout like they do on timing towers.

Let's say lane 4 is leading, lane 1 is second, and lane 3 is in third place, then the first display should show a '4', the second a '1', and the third a '3'. If lane 1 and lane 3 pass lane 4... then the first display would show '1', the second '3', and the third '4'.

If anyone has any ideas on how to do this.. I would be interested.

The counter itself is no probs - just using IR/emitters in the start tower, and IR detectors in a modified track feeding straight into 4026 counters connected to 7 seg displays. Just had some spare space on the display board and a few extra displays - and thought a leaderboard would be a good idea... but couldn't work out how to do it.

[pebe]

You need to give some thought about how the results will be displayed. Until the laps for each channel are different there can be no result, so presumably there will be no display until the first three cars have completed the first lap. And how do you display the results when one is in the lead and another is trailing but the other two in the middle have an equal number of laps?

I think your best bet would be to use a microcontroller. That could do the lap counting for the four channels, and compare them for display in the way you want. You only need 4 inputs and 6 outputs so a PIC with a 4bit and an 8bit port would do.

[wartnose]

Bought my kids (and me) an ho slot car set for Christmas. Decided it needed a lap counter. Found a design using phototransistors that connects to a computer, but wanted a stand alone unit. Until then, I knew nothing about electronics. To me, the lap counter itself is quite a challenge, but you ask an interesting question. At the risk of sounding ignorant, is there such thing as a timer that can start at the start of the race and time each lap, add the cumulative time, and the car with the lowest cumulative time is shown as the leader. I don't think you can just count laps and show the leader, since they are often on the same lap.

[DROz]

Good point... forgot that.

As far as a lap counter is concerned - all you need is 2 4026 I.C.s and 2 7 segment displays per lane (99 laps is enough, if you want more you can run it in stages).

I am using IR emitting LEDs (in the Grand Prix start light tower), and IR detectors from old mice mounted in a 3"track (drill holes for the IR detectors to be able to detect the IR LEDs, then use flat ribbon cable to a small instrument case, and a syuitable cable and plug to connect to the counter).

You can find my Grand Prix Starting Light design at Silicon Chip (Australia) magazine website. If you want the URL - I'll hunt it up for you. Or I could email the Circuitmaker2000 file of the design. The lights recreate the two rows of five lights that come on in pairs, hold, then all extinguish.

http://www.siliconchip.com.au/cms/A_30628/article.html

If you really want timing - the only way is with those PC based software programs, and the special joystick port, printer port, or serial port cables that some places sell that are wired to a detector track.

I use IR because it's not affected by ambient light, and by placing the sources in the start tower (an AFX lap counter that has had the mechanics ripped out and interior baffles removed to fit the circuit and display boards) so that fraudulent triggering can't easily occur.

[wartnose]

Starting light tower is impressive. I don't suppose you have a schematic for your lap counter do you. I'm pretty new to this.

[DROz]

Tried to find a link to a counter for you - but no luck.

It's simple enough though, use a 4026 IC and 7 seg display for each digit (for 2 digits per lane, 2 4026 ICs and 2 7 seg displays are needed, you connect the carry out of the first counter to the clock in of the second). repeat this arrangement for each lane of the set. For a reset button - use a momentary pushbutton connected to the reset pins of all the 4026 chips.

Google for the 4026 IC datasheet and download.

The track sensors depend on what IR detector you use, but their output should be fed into the clock input of the relevant first stage 4026 counter for each lane.

It's really as simple as .. IR detector>>>4026 IC>>>>>7 seg display

[wartnose]

I'll try. One more newbie question. I want to use a larger LED (2.3). Is that possible with 4026. Thanks.

[DROz]

any 7 segment common cathode LED display can be used with the 4026.

[samaste.march]

Micro controller is lap counting for four channels. It need four inputs and six outputs . The laps for each channel are different.

[jonyroger]

It is quite simple, although the use of IC 4026 and 7-segment displays for each digit . Repeat this provision each band in September For a reset button - to use a button connected to reset pin of all the 4026 chips.

[calatheamartinez]

The sensors will depend on the infrared detector mode to use, but their production must be introduced into the clock input of the first stage of 4026 cons for each channel. Micro tower cash control for four channels. It has four inputs and six outputs.