QUOTE (BEEJAY7 @ 3 Nov 2004, 18:47)Excellent, and it could not have come at a better time, as I'm now committed, (more or less) to building one and I know JP is wavering.
Could you describe in more detail the "dead" strips and how you will include timing, as this is one area, (among many others!), that I haven't got a clue about.
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Regards
Alan
<{POST_SNAPBACK}>
The "dead strip" is essentially a switch. It is a 4" length of braided track with 1" gaps in the braid at each end. The power braids are jumpered across this 6" gap (I also use this connection as one of my power feed points) One side of each of the dead strip braids are connected, in common, to the ground return on the lap counting/timing system. A separate wire runs from the other side of each of the lanes to the timing inputs on the system. As a car passes over the dead strip, it effectively shorts that input to ground and triggers the counting/timing function. This is a common type of input for most computer based systems. Any other trigger, such as a light bridge/photodiode combination will accomplish the same end. The only really critical dimension is the gap. It must be long enough so that the braid on the car cannot close the gap and feed power into the computer input. One inch is long enough. The length of the dead strip needs to be long enough to fit the response time of the computer input board. None of the systems that I have seen needs more than 4". The calculation looks something like this (imagine the back of an envelope or a slightly soiled napkin) A fast lap might be 60' in 5 seconds - that's 12'/second - assume that the straigtaway speed is 2X the lap average or 24'/ second. A 4" strip will close the contact for 14 milliseconds - pretty long time in the computer world! I see no apparent "lurch" or hesistation as the cars cross the dead strip - just don't stop on it!
Jim Butt (Subdude 01) and I built our tracks as a joint project. We have both made the same singular observation - to achieve the same apparent speeds that we saw on our Scalextric tracks, we have turned the power down. This may be an illusion due to the very smooth operation or it could be that the braid/braid interface is a more efficient power transfer system than braid/rail or that the hefty cross section of the braid and the lack of joints avoids some power loss.
My overall reaction - Why didn't I do this years ago? - There is simply no comparison. BTW - mindful of the vagaries of life, my track is designed to come apart into 5 pieces, the largest of which is 5' X 8' - the size of a full sheet of MDF.
Happy routing!
EM
PS - If one has the manual dexterity to erect the top on a Healey, one can rout a track!
Could you describe in more detail the "dead" strips and how you will include timing, as this is one area, (among many others!), that I haven't got a clue about.
Regards
Alan
<{POST_SNAPBACK}>
The "dead strip" is essentially a switch. It is a 4" length of braided track with 1" gaps in the braid at each end. The power braids are jumpered across this 6" gap (I also use this connection as one of my power feed points) One side of each of the dead strip braids are connected, in common, to the ground return on the lap counting/timing system. A separate wire runs from the other side of each of the lanes to the timing inputs on the system. As a car passes over the dead strip, it effectively shorts that input to ground and triggers the counting/timing function. This is a common type of input for most computer based systems. Any other trigger, such as a light bridge/photodiode combination will accomplish the same end. The only really critical dimension is the gap. It must be long enough so that the braid on the car cannot close the gap and feed power into the computer input. One inch is long enough. The length of the dead strip needs to be long enough to fit the response time of the computer input board. None of the systems that I have seen needs more than 4". The calculation looks something like this (imagine the back of an envelope or a slightly soiled napkin) A fast lap might be 60' in 5 seconds - that's 12'/second - assume that the straigtaway speed is 2X the lap average or 24'/ second. A 4" strip will close the contact for 14 milliseconds - pretty long time in the computer world! I see no apparent "lurch" or hesistation as the cars cross the dead strip - just don't stop on it!
Jim Butt (Subdude 01) and I built our tracks as a joint project. We have both made the same singular observation - to achieve the same apparent speeds that we saw on our Scalextric tracks, we have turned the power down. This may be an illusion due to the very smooth operation or it could be that the braid/braid interface is a more efficient power transfer system than braid/rail or that the hefty cross section of the braid and the lack of joints avoids some power loss.
My overall reaction - Why didn't I do this years ago? - There is simply no comparison. BTW - mindful of the vagaries of life, my track is designed to come apart into 5 pieces, the largest of which is 5' X 8' - the size of a full sheet of MDF.
Happy routing!
EM
PS - If one has the manual dexterity to erect the top on a Healey, one can rout a track!
