My layout will use physical panels to set turnouts, with switches, DPDT. With two wires, one for straight, one for divert (and of course the common wire). My question is: what is best in terms of reliable, fail-safe operation? A. MTS223 type (ON)-OFF-(ON) momentary with central rest or B. MTS202 type ON-ON, this is the classic up or down switch. In case A there will continually be a default 5V on both wires except when toggled for turnout action, on one of the two wires. Advantage: easy fault finding when a wire is broken or short circuited In case B there is straightforward always an opposite signal on both wires. What is preferred? And why? Thanks for your help! EDIT: the switches will not drive relays or motors or... just straight into a digital high impedance input on an electronic module.
Neither is necessarily more reliable, but there are other things to consider: With a non-momentary switch, you do not need two inputs and you only need a SPST switch. Normally you would have the input tied to +5V through a resistor and the switch would short it to ground. When the switch is open you get a 5v input and set the turnout one direction, when the switch is closed you get a 0v input and switch the turnout in the other direction. With a momentary switch you do need two inputs (unless you want the single input to toggle the turnout), but you only need a SPDT. Each side of the double throw would connect to an input with a pull-up resistor and the common would connect to ground. The advantages of the non-momentary switch is the switch would show the turnout position and it would only take one input. The advantage of the momentary switch is if need be you could throw the turnout from multiple locations using multiple momentary switches.
I used a momentary push button switch with a bicolor led to indicate the turnout position. If you want to stay with a toggle switch, a standard ON/OFF switch should work. When open ,the turnout will be in one position, then when closed the turnout will change to the other position. This may or may not work depending on what your electronic module is. I use an Arduino so any switch can be programmed in.
I'm no expert in this specific application, but I have plenty of experience in electronic systems and human interfaces for them. Option A does not continuously, physically indicate present desired state of the track switch, whereas Option B does. If your turnouts are at any time automatically controlled, regardless of the physical panel switch setting, then A is better. The physical panel switches can request that the switch be closed, but do not continue that request once the operator takes their finger off the momentary switch. If not, and the system always throws/closes the track switch in accordance with the panel switch position, then B is better. This means, at power-up, the system will read the current panel switch positions, and command the track switches accordingly, whether you intended that or not.
Many thanks for these great answers!! I had not even thought about the control from different locations, excellent ideas!
I'm also using non-Arduino or DCC controlled turnouts with servos. Using simple switches with LED route indicators. Could be used on a DC or DCC layout and no computers, Arduino's or much wiring experience needed. A switch box is shown above with one of the tops that can be printed but the switches could be on a control panel with a number of switches. One can have the servo, servo controller, switches, LEDs and other parts for less than $10 a turnout. Recently someone wanted to use the parts to control the servo/turnout from two locations and I came up with the following wiring diagram.... I haven't used it yet but feel it will work fine. The servo controller needs to be wired as per the instructions on my site though (this isn't a universal solution)... http://1fatgmc.com/RailRoad/Servo Control/Servo Control-Index.html Sumner
Yes.... .... in this case with the limit switch that is on the servo bracket shown bottom right in the image above. You can also print or use a bracket that can hold two limit switches (one on each side) if you want to operate something else such as signaling or if you are operating the servo from two locations like in the wiring diagram shown above. The second limit switch could then be connected to route indicating LEDs at both locations. A number of the mechanical (non-servo) switch machines I've designed can have limit switches either at/on the switch machine under the turnout or on the switch machine control at the edge of the layout. Much more info on all of that here.... http://1fatgmc.com/RailRoad/Trackwork/Trackwork-Index.html Also if you are only controlling the servo location you would use the wiring diagram here and not the one above..... http://1fatgmc.com/RailRoad/Servo%20Control/page-7.html Sumner
