broadbent Posted September 20, 2017 Share Posted September 20, 2017 I expect the answer (if there is one) will be more complicated than the question, which is I would like to have 2 input wires and 1 output wire. One input wire comes from the frog and the second comes from one side of the track. If they are the same, then the output wire will also be live, if not then there is no power to the output. Link to post Share on other sites More sharing options...
RMweb Gold Colin_McLeod Posted September 20, 2017 RMweb Gold Share Posted September 20, 2017 What is the question? Link to post Share on other sites More sharing options...
broadbent Posted September 20, 2017 Author Share Posted September 20, 2017 How do I do the switching? Link to post Share on other sites More sharing options...
Pete the Elaner Posted September 20, 2017 Share Posted September 20, 2017 Brian Lambert's site is often referred to on here for electrical diagrams. It contains a lot of good information & a google search will find it quickly. I prefer to use micro-switches than either Peco's PL-13 or Gaugemaster's included switch, because I have found both unreliable, so you need to know how the switch works. A multimeter set to resistance will show you which connections to use much more easily then I can explain it in words. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted September 20, 2017 RMweb Premium Share Posted September 20, 2017 I expect the answer (if there is one) will be more complicated than the question, which is I would like to have 2 input wires and 1 output wire. One input wire comes from the frog and the second comes from one side of the track. If they are the same, then the output wire will also be live, if not then there is no power to the output. If you are trying to switch power to the frog, the common terminal on the switch goes to the frog and the two rails go to the normally open contact & normally closed contact. http://www.brian-lambert.co.uk/Electrical%20page%202.html Link to post Share on other sites More sharing options...
Crosland Posted September 20, 2017 Share Posted September 20, 2017 This is difficult in the DC world. Imagine your inputs are from rail A and the frog. If the frog and rail A are at the same potential then it could mean: (1) They really are the same, e.g. frog is connected to rail A and rail B is at a different potential. (2) They are different, the frog is connected to rail B, but the controller is turned down low enough that the detection circuit doesn't detect the potential difference between rails A and B. An explanation of what you are trying to achieve (the why?) would be useful, rather than just asking how?. Link to post Share on other sites More sharing options...
broadbent Posted September 20, 2017 Author Share Posted September 20, 2017 As a fail safe, I am trying to stop a train getting derailed if a point is set against it. The idea is to have a length of rail next to the frog having no power if the frog has the same polarity as the opposite rail and thus preventing a short-circuit. I had thought of a micro switch, but I would like to do this as simply and cheaply as possible. Link to post Share on other sites More sharing options...
RMweb Gold Enterprisingwestern Posted September 20, 2017 RMweb Gold Share Posted September 20, 2017 Apologies if I'm not understanding the question, but if you're attempting to switch different bits of track from one or more inputs, then you need to investigate relays. Mike. Link to post Share on other sites More sharing options...
DCB Posted September 20, 2017 Share Posted September 20, 2017 As a fail safe, I am trying to stop a train getting derailed if a point is set against it. The idea is to have a length of rail next to the frog having no power if the frog has the same polarity as the opposite rail and thus preventing a short-circuit. I had thought of a micro switch, but I would like to do this as simply and cheaply as possible. With Live frog points it is very difficult to derail a loco by setting the points wrong as unless there are additional isolators both rails will be at the same polarity. A dead section of one rail adjacent to the frog when the point is set against the train is a good idea (DC and DCC) as a loco bridging an isolator against the frog can cause a dead short. Switching the frog with a microswitch is easy enough but isolating the other rails is more complicated and I can't see any way apart from a Microswitch / relay combo or maybe 3 micro switches. Link to post Share on other sites More sharing options...
Pete the Elaner Posted September 21, 2017 Share Posted September 21, 2017 An explanation of what you are trying to achieve (the why?) would be useful, rather than just asking how?. That is always helpful. The best solution can sometimes be vastly different from what the asker ever considered. Link to post Share on other sites More sharing options...
RMweb Premium Ray H Posted September 21, 2017 RMweb Premium Share Posted September 21, 2017 Could you use a double changeover relay operated by what ever you plan to use to switch your frog polarity. Rail A is (say) linked to the normally open terminal (n/o) of one changeover sets and Rail B is linked to the normally closed terminal (n/c) of the same changeover set. The common terminal of that changeover set is connected to both the frog and the common terminal of the other changeover set. The n/o terminal of the second changeover set is connected to the isolated section that is a continuation of rail A and the n/c terminal of the second changeover set is connected to the isolated section that is a continuation of rail B. We use something similar to avoid a head-on over a diamond crossing on our club layout. Link to post Share on other sites More sharing options...
NinOz Posted September 21, 2017 Share Posted September 21, 2017 I expect the answer (if there is one) will be more complicated than the question, which is I would like to have 2 input wires and 1 output wire. One input wire comes from the frog and the second comes from one side of the track. If they are the same, then the output wire will also be live, if not then there is no power to the output. I would try connecting the track and frog wires to inputs of an AC optocoupler (or two normal ones). If the same potential on the inputs then no output from the optocoupler if different potential then there will be an output. The output from the optocoupler could drive a relay, power transistor or provide a digital signal. Would require at least a volt or two DC to get it operating but if you have locos moving about will be no problem. From memory the H11AA1 (or equivalent) would be suitable. Regards, CFJ Link to post Share on other sites More sharing options...
broadbent Posted September 22, 2017 Author Share Posted September 22, 2017 Any chance of a diagram? I am a complete electronics dunce. Link to post Share on other sites More sharing options...
Pete the Elaner Posted September 22, 2017 Share Posted September 22, 2017 (edited) Oops. Answer posted on wrong thread. Edited September 22, 2017 by Pete the Elaner Link to post Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now