When Louise's cousin Herman visited a few weeks back, he knew of a much more reliable detector component that acts as its own transmitter and receiver i.e. it sends a beam out and detects when it gets reflected back. Herman kindly wired up four of these sensors onto a relay card. They arrived from Malta a few days ago and I linked Herman's card to the interface card I cobbled together from a gamepad.
The sensors are about 20mm deep so as well cutting holes in the track, I had to cut openings in the table to fit them under the track. All the wiring is out of the way under the table (except a single USB cable to plug into the laptop) so this is all you can see from the track...
...and from above...
I've got two pairs of sensors installed in the track - the first pair are wired up to detect laps as the car passes and the second pair act to refuel the car when the software is in fuel management mode, when you stop your car over the top of them.
This setup is a huge improvement. Some of my cars have shallow slot guides that didn't always trip the mechanical switch. And some of the cars were so fast, they could sometimes drive straight through the mechanical switch without triggering it. I've seen other sensor setups but they usually have a light bridge over the top - sometimes quite subtle, but sometimes (like my first attempt) with halogen lamps burning down on to the track. These self-contained sensors do away with this, look much neater, and work much better - so many thanks to Herman!
Wow! This is really neat. Could you explain in a little more detail the cons/problems you were/are having with these sensors? I failed to catch what type of IR sensors these are; could you tell me what Herman used? Or perhaps even get me in ouch with Herman? My email is abimaelleon @ gmail.com Thank you for your good work. I hope to hear from you soon.
ReplyDeleteThe IR sensors I used are made by Baumer Electric but I think there are cheaper ones available. I've posted the circuit diagram and data sheets for a couple of the components on Slot Car Illustrated. See http://slotcarillustrated.com/portal/forums/showpost.php?p=533039&postcount=27
ReplyDeleteHi James, what a good job! Congratulations! I want to build a similar detector for my track (although I'll build a speed trap) I'm just wondering how reliable your detector is : or how likely it is to miss a detection. Thanks
ReplyDeleteThanks for the feedback. It's proved extremely reliable with one exception. With very fast cars, they will be driving over the refueling sensor a split-second before the lap sensor, and very occasionally the lap is not recorded.
ReplyDeleteI think that this is either that the USB Gamepad electronics can't cope with processing the two signals so close together, or that the car is going through the lap sensor so quickly that the software doesn't do a proper detect. I think it's the former because I've reduced the incidence of this problem by having the refuelling sensor and lap sensor at other ends of the start-finish straight to maximise the distance between them.
I guess I could check this out properly by wiring the refuelling sensors up through one USB gamepad, and the lap sensors through a different one. Now that's an idea...