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dead strip lane counter

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  • dead strip lane counter

    I'm readying to wire my layout snd would liike feedback from anyone who has tried dead rails on HO. It seems like the easiest way is to cut the wire terminals from each end of a 3" piece and combine it with two 6" to distribute power. Drilling through the track made a mess, maybe if I knew someone with a drill press so I could hit the track rails themselves with lik a 1/8" bit. Otherwise, I literally snapped a pair of wire cutters in two trying to cut the steel rail on this thing.

  • #2
    I made a dead section by simply cutting the end connections from a section of Tomy track, I used a cutting disc in a dremel. Just be careful to cut the end of the metal rail and not go into the plastic track. 17850662-38B6-41E9-942C-F926C80F57C2.jpeg


    • #3
      dont know if this would help you but what about the small dead track section from a autoworld dragstrip


      • #4
        It is not difficult to remove the power rails from a piece of plastic track if you have a Dremel tool.

        Grind away the tabs underneath the track and the rails will pull free easily. Then you can cut the rails into sections. The dead strips can be 3 or 4 inches (75mm to 100mm) long. Cut those out of the middle of the rails. Trim the end pieces by 1/8" (3mm) so you can leave an electrically insulating gap. Reinstall all the rail sections using superglue to retain them. Wick the superglue from underneath using the gaps in the plastic.

        Finally you need to solder wires to the underside of the dead strips. Again, use the gaps in the plastic underneath to make the connections. You may need to wire-brush superglue away from the rails locally to get a good solder connection.

        It would be good practice to epoxy the wires to the underside of the track to provide mechanical strain relief. I'd do that away from the solder connections on the off chance you might need to service them for some reason.

        Ed Bianchi


        • #5
          Thanks everyone. I have a couple of squeeze pieces I won't use so I experimeted on that and it's really difficult not to leave the track looking gnarly. If I need a 3" gap I'm thinking of doing it thusly, having a 6" piece before and after (to help straighten the car) then a 3" dead track then another 6". I'll have a lot of 6" sections for power ​​I don't get it. zBoth my previous posts seem to be removed, but I had no links and just talked about the track. What did I do wrong so I won't do it again?


          • #6
            Timely thread.
            I was thinking of doing the same on a small track that I have in the planning stage.


            • #7
              OK that wasn't as difficult as I anticipated. One half down, half a dozen more to make. Thanks again. 20210611_102853.jpg


              • #8
                Screenshot from 2021-06-08 00-12-32.png
                A lot less work than operating on 6" straights AND 3" straights not to mention buying another 20 pieces of track.


                • #9
                  Round the edges of the rail at the start and end of the dead strip. You want to minimize pickup bounce. It don't count if one or more pickups are in the air. The following is taken from my Siberia Racing Tech Pages article on testing lap counters.

                  For a dead strip installation, the lap counter system is tested by taping over more and more of the dead strip rails until the lap counter becomes unreliable. Like the optical system test the car is driven as fast as possible. I start by taping half of the length of the dead strip over. I start taping from the end of the dead strip working toward the beginning of the dead strip to check if pickup bounce was causing a problem. I would then run the fastest car I had over the counter for a minimum of 20 laps in each lane. If all laps are detected, I consider the system to be reliable. I would then repeat the test with more and more of the dead strip taped over until the system became unreliable.

                  The last successful test provides the minimum update time (or distance) required for the system to operate. I would then run a separate test where the center half of the dead strip was taped over to verify that the system did not double count. This second test was done at various speeds. At the end of the second test the car is going around at a speed that just allows it to coast across the dead strip without stopping.

                  With a dead strip an important item to look for is the transition from the track rails to the dead strip section rails. You don’t want the pickups to bounce over this transition as this can lead to problems. Floating pickups do not provide an input signal to the lap counter. Likewise, bouncing pickups shorten and reduce the quality of the signal provided to the lap counter.

                  The purpose of the test is to determine for is how much of a time (or distance) margin exists between the time required for the car to pass through the detector and the last successful test. For example with the Magic Raceway test car I have a safety factor of five as the wings are one fifth the length of the car. With a dead strip that operates successfully with 80% of its length taped off the safety factor would also be five. I want my lap counter systems to have a minimum safety factor of three when all lanes are triggered simultaneously. Obviously, I am quite happy with a safety factor of five.

                  Unfortunately the dead strip method only tests one lane at a tine. With an optical system it is possible to test multiple lanes simultaneously. Testing multiple lanes simultaneously rings out the entire system and identifies any weak links. I had a weak link in my latest lap counter design that only showed up when three cars crossed the line simultaneously,
                  Last edited by Maddman; 06-11-2021, 05:56 PM.


                  • #10
                    This counter system will not bounce. Thanks to $3 microcontrollers, A 16 input track presence detector will cost about fifty bucks. I've looked at a LOT of web pages devoted to these things and, quite frankly, I haven't seen a single design that makes sense in the dead track interface. Because the track is built in sections, each of three sections will have its own counter circuit that communicates track events via an MQTT server/client based on an arduino and a raspberry pi. Because this is "portable" the only wires connecting the three sections will be ten pin bournes connector: 2 wires for each lane, plus 12V for track power. each section has one of these wifi modules in it, so no sensor wires to keep track of - just keep the sensor wires paired, connect the track to the board, and setting up the track once wired will simply involve making one pass in each lane. This will tell the rpi the order to watch for event numbers. It can also track times for diffferent sections of the track. As you can see from the track layout, the middle section has only one detector per lane but the laft section has three, requiring 12 of the 16 detector inputs to a board.

                    As a retired hardware engineer and systems consultant, I'm dead sure this thing won't "bounce" except, of course, if I jigger up the mechanicals of it. It uses wifi to send each event to an MQTT broker. The pi also is a client of that broker and the arduinos are all set to have a timing counter accurate to about 5 decimal places so they are all in sync. Duplicated events will simply be ignored - if you pass detector 3 in blue then it won't register another time unless it's coming from detector 4 blue. How they are wired is meaningless just so long as one dead rail detector is wired to one input channel. The entire thing is optoisolated and you don't have to worry about track polarity for a detection event. Because there are three sections, there will be three of these circuits, all talking wirelessly to both the track and the pi will collect the data and control the track speed based on a wired controller frankensteined from the little afx controller; the 120 resistance actually works better in this as it's easy to pump a 10mA current source and get 0 to 1.2v wihich is easy peasy for an A/D to monitor.Screenshot from 2021-06-11 19-37-18.png

                    I really do appreciate the feedback. I went to the Siberia Racing website and couldn't find an article about dead strips. It's an interesting site, just not helpful here based on what I've found there..


                    • #11
                      The original Aurora Electric Lap Counter used a fully powered 9" straight as the lap counting track. The track looked like a normal terminal track except it was electrically isolated from the rest of the layout (the ends of the rail came up about 1/2" or so short of the end of the track). Of course the lap counter itself was designed to handle the 20 volts or so that was running through it.

                      I am no electrical guru, but I'm guessing it might be possible to do the same thing with a PC as long as you reduce the voltage getting to the PC.



                      • #12
                        Ya wanna know how to power the dead strip without zorching the computer? Stone age technology! Install a electromechanical click-clack relay in the circuit to feed a switch closure to the lap counter. Use the current going to the slotcar to trip the relay.

                        You might need a longer dead strip to give the relay a long enough pulse to close -- but no matter -- the dead strip is powered so it can be longer.

                        Better yet, every time a relay closes you'll get an audible click. Some of that 1950's pinball techno-ambiance!

                        Ed Bianchi

                        PS - I had two of those Aurora electromechanical lap counters for my 1969 routed HO slot track. I bumped up the power to them with a 6-volt lantern battery so the added resistance of the lap counter relays wouldn't cause the cars to slow down on the detector track section. You might want to juice your 21st Century rig like that too.
                        Last edited by HO RacePro; 06-12-2021, 03:43 AM.


                        • #13
                          You don't have to solder wires to the rails, try this:


                          • #14
                            Isn't the point of a dead strip to GET power from the motor? The motor acts as a generator, which powers the bridge rectifier (which I have never seen in any schematic for some reason.), which gives a positive pulse to drive the led in the optoisolator. Current drawn by the led is a few milliamps.

                            I have the schematic of the one afx lane detector that slides under the track. My guess from the ttl technology is it came out in the early 80s. It uses a hall effect for each line which will, of course, work so long as you have a strong magnet and go through the lane straight. I know dead strips work, frankly I'm surprised no one has stepped in to make them!

                            Can you tell me what I am doing wrong? I can't get the rail to always go back to the nearly flush level it was when it came out. I filed a couple of the prime offenders, but I'd rather make something that doesn't look such a kludge.


                            Attached Files
                            Last edited by boxxofrobots; 06-12-2021, 07:52 AM.


                            • #15
                              A lot of people don't understand how dead strips actually work, which is OK until something goes wrong. As long as a car's motor is turning it will produce a voltage, but that is not what triggers a count when a car crosses the dead strip. Just a short across the rails will trigger a count. See this article on dead strips:


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