lap counter set up

[rwfoote]

I am new at this electronics stuff and want to be sure I get it right. The material says to buy a Honeywell SDP8436-003 infra red sensor. I find that part number but it lists photo transistor and a couple of other items all with the same code. Can someone tell me specifically what to buy in the US and if you have a good place to buy it, that would help also.

The same questions for the light source for the infra red sensors. What do I buy and from where? Thanks for the help, I know these are dumb questions.

[Nemesis]

RE Lapcounter setup

Hi,

When I made my sensor bridge, I used a couple of Osram SFH4550 Infrared LEDs (1 per lane) together with two Optek OP550B phototransistors (again 1 per lane).

Should be able to find them in the US by searching on the part numbers.

Regards

Edward

[rwfoote]

Perfect, thanks for the help

[rwfoote]

How did you power the SFH 4550?

[Nemesis]

I bought a cheap PC USB cable and wired the IR LEDs to the my laptop 5V USB supply along with a couple of suitable resistors. USB pinout available on the net.

Can't remeber the value I used now but resistor value = (5V-LED forward voltage) divided by the LED forward current. You can find both these values on the LED datasheet.

Ideally you want one resistor per LED both run from the 5V supply for even lighting.

[tonesua]

do you lay the photo resister flat or upright

with the photo resistor you list, do you have it pointing upright? or Flat, with the bubble of the resistor pointed to the IR?

Tony

[Nemesis]

The 'bubble' needs to be pointing at the light source - the IR LED.

I drilled a hole in the track and glued the photo-transistor (not photo-resistor) to the back of the track so that the 'bubble' sat in the hole I drilled pointing up through the track towards the IR LEDs mounted above the track.

Regards

Edward

[tonesua]

The 'bubble' needs to be pointing at the light source - the IR LED.

I drilled a hole in the track and glued the photo-transistor (not photo-resistor) to the back of the track so that the 'bubble' sat in the hole I drilled pointing up through the track towards the IR LEDs mounted above the track.

Regards

Edward

Thanks for the advice. I was able to get two lanes working, the other two didn't as I didn't place the sensor with in the hole area that I had drilled. What glue did you use? Hot glue gun? And how did you glue them? I am looking for something less permanent until I can test. Has anyone glued plastic tubing or plastruct to hold the photo transistors in place?