homemade timing system

[terry.sc]

Originally Posted by Si Coe

I could have sworn I was talking to someone about 18 months back about a system using the same sort of RF tags shops use for security. The loop would be pricy (AMB/Mylaps type money) but the 'PT' would cost literally pence.

This was discussed when we were sorting out our home made club lap counting system. RF tags are way too slow. As an example RF tags are sometimes used in cycle racing, but for the timing to be effective the riders have to get off their bikes and walk over the timing mat to get it to register. It would need something really complex to activate the tag, then pick up the signal while the car has travelled several feet further down the track.


We went for a home made infra red system to run the lap counting at my club, but we did have the advantage of a few club members being electronics and software engineers to develop the system. The system uses small infra red transmitters that constantly transmit a number, which is then picked up by a receiver at the side of the track with a narrow field of vision. The trickiest part of the system was getting the computer to reliably read the signals from the decoder to count the laps, the system we have developed operates much faster than the AMB system so the software has to keep the first signal and reject around 150 others that it picks up as the car speeds past.



As a suggestion for an automatic system that won't help if there's more than one car on the track, but if you are practising on your own a relatively simple hack would be to use a photoelectric beam sensor or anything that can be triggered by movement to act as a switch to replace a number key on an external keyboard which can then act as an automatic key press on a laptop using one of the available free lap counting programs.

For off the shelf options if you have the money there's the TimeR from Dirtchampdesign, for a cheaper version try the i-Lap timing system.

[Yadayada]

Interesting thread , my local club is now struggling with AMB20 transponder batteries , and insufficient funds to replace the system.

So , I started looking around , and found this thread.

I think a webcam system might be viable.

Consider a DIY transponder equivilent(?) made from LED's.
With 7 LED's...
+---+---+---+---+---+---+---+
! Y | R0| R1| R2 |R3 |R4 | G |
+---+---+---+---+---+---+---+

i.e. One Yellow LED , 5 Red LED's followed by a Green LED.
(The actual colours don't matter , but the outer 2 (Y+G) in example need to be different.

Now each of the R LEDS could be enabled via a PC like jumper switch.
5 LEDS gives 32 combinations.

Each car carries the bug on its roof (bit ugly )..

Webcam(s) focused over start line.

Process the images from the webcam.

Find Yellow + Green pairs within the image , between them should be the Red LEDS. Scan for bright or even red parts of the image , we should be able to deduce a binary code for each bug.

Now if the caputure rate is quick enough we should be good to go ?

Could you make a bug for £2 ?
WebCams £20 ?
RaspberryPi to count £30

[Joe_K]

Could you use blue LEDs between the red LEDs to make sensing the on/off state of the red LEDs easier?

[racingben]

Originally Posted by Yadayada

Interesting thread , my local club is now struggling with AMB20 transponder batteries , and insufficient funds to replace the system.

maplin do batteries that can be modified to fit the amb 20 transponders. hardest bit is digging all of the waterproofing off of the pcb first.

[Ema]

Originally Posted by Yadayada

Interesting thread , my local club is now struggling with AMB20 transponder batteries , and insufficient funds to replace the system.

Originally Posted by racingben

maplin do batteries that can be modified to fit the amb 20 transponders. hardest bit is digging all of the waterproofing off of the pcb first.

Here's a more detailed description of what you have to do .
http://abc123.dowco.com/~tom/rc/amb/index.html

Bye
Ema