How would you drive two LED's per turnout (straight and divert) when you have just a downward pulse for each direction? I.e. the control lines are permanently high (5V) and pulsed low for the desired turnout direction. I am thinking of using a flipflop (7400 NAND gate, two gates per turnout) but any alternatives are most welcome.
If your turnout is power-routing (the de-selected route is not powered), then you can use the power status of the two routes to indicate the switch status. Also consider how your circuit will be initialized when turned on, to reflect the current turnout state. The biggest problem with using digital logic gates to make a flipflop is that they are notoriously susceptible to electrical noise.
Here is an alternative- I use an Arduino UNO for this function. The change of state is detected by the UNO input, the program takes action based on the last state conditions. The UNO drives a Quad or Octo relay board that flips two relays at a time, each one controlling a red and green LED with a 2.2 or 2.7kOhm resistor to +5V. Since red and green LEDs turn on at different voltages (about 0.5V difference) I connect the reds to the +5V with 2.7k, and the greens with 2.2kOhms. The relays act to ground one or the other LED, turning it on. I wire them so the relays are in the Normally Off state favoring the most used switch state to minimize the power. I have a bunch of 5V/5A supplies around the layout to feed power to relays and LEDs.
Are you using the eeprom memory to save the state when it is on and off? I've never used it but need to look into it more. Sumner
Hi Sumner I just use a state counter in the program. 0 or 1. Each loop of the program reads the states of N switches. If the state value changes, then that switch, LEDs and signal lights are changed accordingly. Some times when I power up the whole system, states are changed, but the indicators show the "mis-match". A tap on the pushbutton(s) clears this.
From reading the above posts I can't help but get the feeling of a Rube Goldberg concoction. Being a devotee of the K.I.S.S. method I like to avoid complication whenever I can. I use a DPDT slide switch connected to the point rails with one side of the switch used to change the frog polarity and the other side to change the color of a bi-color LED. A slide switch (hand thrown), a bi-color LED, two resistors and some wiring is all that is needed. There are several You Tube videos on the subject.
Power routing switches with DCC, require only a rectifier (half- or full-wave), dropping resistor & LED for each of the two routes from the switch.
LOL Spoiler: Or the K.I.S.S ++ method Deluxe Under-Table Switch Machines? but at $20+/pop perhaps not the most economical . .
I think his "$20+/pop" was referring to the Deluxe Under Table Switch Machine he mentions if you clock on the "Spoiler" button.
The Walthers turnout machines I use have two lever switches that are operated by a cam on the servo that throws the turnout. It operates two entry and exit signals at the Oberrittersgrūn station. Can't think of anything easier than that for signal operation on a turnout.
