Post by Deleted on Mar 26, 2017 3:49:31 GMT -5
Greg, You wrote in a former topic (thank You again for that idea) that the contacts in the turnout can be burnt very quickly ; I understood the problem, and found an additional post about this subject : www.khpost.net/home/Tipps_Info/w.html (in german). In fact, I don't know if the problem is related with the higher voltage of DCC, or if it can occur with "normal" DC too. I will not use power routing, the tracks will be switched through a relay and "insulators" will be put directly on the turnouts (due to the length of the trains, it will not be possible to use an additional piece of track and put the "insulator" to its end, as it was suggested in the German topic) ; unfortunately nothing can prevent a train running into a turnout which didn't switch properly, and so create a short-circuit with the frog or the "mobile part". I think that setting the "little screws" in their respective holes does not solve anything, because current is still flowing through the 4 springs, it seems only to put a permanent "bridge" to the switch. So, my question is : does the power come to the moveable part and the frog through the "slider" (unfortunately on the first picture in the German post it seems to be so), or only via the contact established between the mobile part and the rails ? In first case, I don't see any solution to remove the springs ; in the second case, I could remove the springs, solder "feeders" into the "square holes" (or the circular holes left from the springs) and connect them under the plywood ... and so simulate the "bridges" which exist im Märklin turnouts ; so the only possibility of a short would be with the frog, and I think it is "stronger" than the springs. In first case, I will have unfortunately to rely on the electronic protection : I will use an "ordinary" switching power supply, set to 7.5v or 9v (and the transistor in the PWM provides an additional voltage loss of 0.6 to 0.7v), and the reseller said that the power supply has an electronic short-circuit protection, which triggers in a few milliseconds (I hope he did'nt mean 1000 ... 
). Perhaps it's sufficient ... But I can't understand the problem of the German modeller : I was always thinking that DCC power supplies had a very (or perhaps too) fast and efficient short-circuit protection !
To my great shame I must add that I didn't yet try to look inside a turnout ... I only saw pictures !
The only idea that I could have follows : as far as I could understand, the turnouts are controlled via a mobile "sled", containing 2 magnets of opposite "polarity", which moves back and forth in front of the coil. Perhaps a reed switch under the turnout near to one end position of the sled would be closed in only one position of the turnout (if the "amplitude" of the sled's movement is sufficient) and could so provide a reliable feedback to the control system ; because every turnout or group of 2 turnouts will be controlled by one bit, a digital comparison between all control bits and position feedbacks of the turnouts could, in case of a difference, trigger an alarm condition (after about 0.5 s). On my layout there won't be more than 10 or 12 turnouts, so the solution could perhaps be interesting.
Thanks for any answer ...
PS : this a supplementary argument for fixing the tracks with screws and not to glue them : if I have to replace a turnout, I will have to remove some adjacent sections of tracks, and this is easier with screws than with glue !
). Perhaps it's sufficient ... But I can't understand the problem of the German modeller : I was always thinking that DCC power supplies had a very (or perhaps too) fast and efficient short-circuit protection !To my great shame I must add that I didn't yet try to look inside a turnout ... I only saw pictures !
The only idea that I could have follows : as far as I could understand, the turnouts are controlled via a mobile "sled", containing 2 magnets of opposite "polarity", which moves back and forth in front of the coil. Perhaps a reed switch under the turnout near to one end position of the sled would be closed in only one position of the turnout (if the "amplitude" of the sled's movement is sufficient) and could so provide a reliable feedback to the control system ; because every turnout or group of 2 turnouts will be controlled by one bit, a digital comparison between all control bits and position feedbacks of the turnouts could, in case of a difference, trigger an alarm condition (after about 0.5 s). On my layout there won't be more than 10 or 12 turnouts, so the solution could perhaps be interesting.
Thanks for any answer ...
PS : this a supplementary argument for fixing the tracks with screws and not to glue them : if I have to replace a turnout, I will have to remove some adjacent sections of tracks, and this is easier with screws than with glue !
