If I can stop the train in front from resetting the signal behind to green until he has left the section this won't happen.Ī circuit that produces a 0v output when the train in front 'leaves' the insulated section is what I am looking for.
Sometimes if one driver is fast enough, when he sees a signal go to green (the train ahead has triggered the system and set the signal behind him to green) the driver moves off, if his train has cleared the short section before the train in front has cleared his then the train in front sets the rear signal back to green when the rear train is in the section. I have recently removed a large number of proximity sensors as they are not reliable enough for us and replaced them by insulating a small section of one rail, connecting a wire and earthing the other rail.Ĭonnecting the insulating section to the present circuit as described earlier allows the present circuit to function quite well. If I can add small units to make a better job of the running of the system I feel that will help. I am using latching relays because the circuit has been in existence for many years, is quite large, has worked fine most of that time, most of the people on the maintenance team don't understand much about electronics and I am trying to make improvements without losing them in electronic systems they won't touch. The present system has LED's that light whilst the train is on the 'short track' and work quite well. The circuit voltage is 24v DC but as the resistor and the coil are similar resistances (about 680 ohms) the potential divider leaves me with 12v below the resistor and 0v below the coil. The signal then resets a latched relay by earthing the point between a resistor and the relay coil or sets the relay by being connected between the other end of the coil and one of its contacts.
This occasionally results in two trains in one section if the second train is moved fast enough. If I don't get an output until the input has disconnected again I can use that to close a relay after the last wheel has left the short section and change the signal light to green to let another train pass, at present the moment the train hits the 'short section' the light changes allowing the train behind to move. It is not 'very clean' because the signal is earth and is picked up by one wheel which through the axle reaches a short section of the other rail that is insulated from the rest of the rail and is connected to the input. The input is derived from connecting it to one track of a garden railway. Or, are you simply trying to make the LED show anĪverage Input-State over a defined Time-Period ?
What will the "One-Second-Pulse" Indicate ? It would make understanding what You are trying to do much easier. If you would just state the overall problem that you are trying to solve Or just one LED indicating the new "One-Second-Pulse" ?
Will You still need an LED Indicator that flashes in response to the "Noisy" Input ?ĭo You want an additional LED that Indicates the new "One-Second-Pulse" ?, How much Current will the Output-Pulse have to Source or Sink ? What specific Voltage is considered to be "High" or "On" ?ĭo you want a Positive, or a Negative, Output-Pulse ? What specific Voltage is considered to be "near-zero" ? How long of a Time-Period must it remain "near-zero" before you want a "one second Output" ? What are the Voltage Levels that are considered to be "High, and "Low" ? Is it a Binary Signal ?, (either Off or On), or is it an AC Voltage ?