I've been knocking this around now for a couple of weeks and can't come up with it on my own. I have an Atlas double slip switch for O gauge. 3 wires, middle is ground, outsides are hot. I'd like to have a train run up to this switch and throw it automatically so the trains cross over automaticall every time they approach the slip switch. I'm trying to do this by using insulated track pieces and making the ground side make the connection. Yes, a cross over would have worked nicely,but I cannot find one that would have worked into the game plan like the double slip switch. I can make the switch worked automatically if I wire up only one hot terminal on the switch, but that only throws the switch one way. As soon as I wire up the other hot lead, the switch acts as if it's full of glue ( which of course it is not ). If I push the switch by hand, it will try to work back the other way, but again, as if it's full of glue. 16-18 volts on the switch, so I can't figure out why this is happening. Any ideas? Thanks to all, Jake
I am using a DSC system, can't it be programmed to do this work for me each time a train approaches?
When you say, "3 wires, middle is ground, outsides are hot", do you not mean that there are two coils, that the "middle" wire is connected to both coils, and that each of the other wires is connected only to one coil? If that is the case, the middle wire is not or should not be considered "ground". Connect it to the center rail or, if you want, to an accessory voltage that has its return in common with the outside rails. Then connect each of your control rails to the appropriate one of the other two wires.
Bob Nelson
Connect the turnout common, which is the wire that is connected internally to both the coils and apparently is the wire in the middle, to the supply voltage for operating the coils. Connect each of the other two wires, each of which is connected internally to only one of the coils, to a control rail, that is, an insulated section of outside rail, located where you want to sense an approaching train that is going to switch the turnout.
As for that supply voltage, it should be returned to the outside rails generally (those outside rails that are not control rails). This can be (1) the center rail of the track, or (2) an accessory voltage on the same transformer that you are using to run the trains, or (3) a voltage from another transformer or DC supply that is returned to the outside rails generally, or (4) a capacitor.
Dale's point is valid, that if you use (2) or (3), the train could stop on the control rail, operating a coil continuously and burning it out. You can avoid this problem in most cases by using (1), with the idea that, when the train stops, there is no voltage available to the coils. (This is the approach that Lionel took with the O27 turnouts.) He suggests (4); and that is what I use. However, no relays are needed. Just hook the turnout common to the capacitor and return the capacitor to the outside rails, as if it were a power supply. You then need to provide a way to recharge the capacitor. You can do that with a 100-ohm 10-watt resistor connected between the capacitor and a single rectifier diode, like a 1N4001, in series with that. If you ground the negative terminal of the capacitor, the diode's cathode (the striped end) should point toward the resistor, which will connect to the positive capacitor terminal. The other end of the diode, the anode, will connect to an accessory voltage like you might have used in (1), (2), or (3).
If you want to go this way, why don't you tell us what transformer(s) or supplies you're using or have available, so we can tell you more precisely what to connect to what.
Dale, I would suggest putting a little resistance in series with the charging circuit, to limit the inrush current through the contact when the relay releases.
I don't see the point of using relays for this. Think about the resistor that I just suggested. It can actually be quite large, since there is no great hurry to recharge the capacitor--a few seconds is fast enough. But, if the resistor is that large, there is no real need ever to disconnect it from the charging supply, since the recharge current that continues to flow after the capacitor is discharged but still connected to the coil is small enough to be harmless. With the need for the normally-closed contact gone, the control rail can perfectly well be used directly to connect the coil to the capacitor, eliminating the need for the relays, bridges, and the smaller capacitor.
Reducing the charging current also makes it easy to obtain from a simple single-diode half-wave-rectifier circuit powered from any convenient AC accessory or track voltage.
I have found that an incandescent lamp suitable for the recharging-supply voltage (I now use a regulated 16-volt DC supply), like a number 53, recharges the capacitor faster than a resistor, for the same recharge current through the coil. This is helpful to me since I now use a single capacitor to throw up to 7 turnouts at once, requiring a substantial increase in the capacitance, but still need to keep the recharge current low when only one turnout in the group is thrown.
Jake, I've been wondering how you are planning to use this slipswitch. It must have two states if it has two coils. I imagine that one of them configures it to act like a crossing and the other one doesn't, that is, it makes it act like two overlapping curved track sections. Am I right? And where will you locate the control rails and how will they arrange the slipswitch?
None of this has anything to do with the way you power the coils. But I'm just curious about what the grand scheme is.
Bob, this thing is blowing my mind. I cannot figure out how to make it work. I'm not sure just yet exactly how this will work, but if we can invent a device for nailing studs, trim, space travel, living underwater, jet travel, parachuting, etc, I HAVE to be able to make this switch work this way! Jake
Any and all ideas you toss my way are most appreciated.
Fred- Get a hold of Atlas, they will tell you how to wire that swtich so it works properly. The only thing that is wrong with that print is that you have to have the switch throw. (the power that moves/throws the turn out) seperate from the power throw. which will swap the center rail power from one rail to another That will become more clear when you get the print from Atlas. I belive this will get you started on the right track. If you need further assistance make a reply and I will try to get a hold of you. phone or e-mail,
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