Points and DCC

[Cowley]

I keep forgetting to say that this has been very useful. Thanks to those that have contributed.

 

[Belperpete]

The PCU-2 is here. From the picture provided, there is an "AUX IN" screw thing (screw terminal?) which I assume is where the wire from the transformer screw terminal would go, and there is also an "AUX OUT" screw terminal, where I assume the wire back to the transformer would go, thus completing the circuit. Furthermore, I assume I could also attach the wire from the "AUX OUT" terminal to the "AUX IN" terminal of another PCU-2, and then the "AUX OUT" of the second PCU-2 would go back to the transformer? My thinking is that I could do the same as Barrie Davis (as in using the Gaugemaster systems) but as I described in post #1 of the thread - the point control would be separate (electrically) from the DCC train control system, thus making it simpler and easier.

Looking at the photos, I think that the PCU-2 is just a box with seven switches wired to a terminal block. Personally, I would not pay £43 for seven switches in a box. The PCU-2 is designed for use with a PCU-1, which includes a capacitor-discharge unit (CDU). Without a PCU-1, I think you would also need to buy a separate CDU - if you fed the PCU-2 directly from a transformer without a CDU then you might burn out all your point solenoids, depending on what type of switches are on the PCU-2.

The PCU-2 seems to be just an expensive way of buying seven switches wired into a box. There are much cheaper alternatives:

1) probe-and-stud. As explained by SCH117X, this is the simplest and cheapest, and the quickest to get you up-and-running. You can always upgrade to one of the other options later-on. Draw a sketch of your track layout onto a piece of paper or card, and stick it onto a piece of hardboard or ply. For each point, stick two studs into the plan, one to throw the point left and one for right. Solder a wire to each stud, and run it to the appropriate left or right terminal on the solenoid. You then just dab the probe onto the relevant stud and the point will throw that way. PECO make suitable studs and probes, but you can also use brass-headed drawing-pins or screws.

2) push-buttons: you would need two push-buttons for each point, one to control the point left and the other to control it right

3) switches: one two-way switch per point. Throw the switch one way, and the points move left, throw the switch the other way and the points move right. These should be momentary or passing contact switches, so that the power doesn't remain permanently on. You can mount the switches geographically on a layout plan, so that the position of each switch matches the direction its points are set. Or you can mount the switches in a row, like a lever-frame.

4) lever-frame: Triang used to make switches that looked like a lever-frame. You can buy these second-hand for about £2 each - searching for "triang lever" finds loads on ebay. So you could get 7 for £14, as opposed to the £43 for 7 switches in a new PCU-2. Different colour lever-switches are used for different functions - you would need the black passing-contact switches (R44) for point operation, not the yellow or green levers. If the idea of mounting and wiring up your own push-buttons or switches on a panel seems a bit daunting, then this is the option that I would go for. Simply clip as many levers together as necessary, run one wire from the CDU output to the lever-common, and then two wires from each lever to its associated solenoid.

The following page on the Gaugemaster site explains the various options in more detail:
http://www.gaugemaster.com/articles/guides/point-motors-solenoid-basics.html

With all the above methods, and the PCU-2, you would need to run two wires from each solenoid to the control panel. So you could change from one method to another later on. Again, with all these methods, the return terminals of all the solenoids should all be fed back to the negative output from the CDU. You can run individual return wires back from each solenoid. However, the simplest is to connect them all together on a terminal or bus-bar under the layout, and then just run one wire back from that to the CDU.

If you have two points that can always be operated together, such as a crossover, then you can simply wire the second solenoid to the first solenoid (A to A, B to B, C to C), so that both solenoids operate together from the same control.

 

[Peter C]

Looking at the photos, I think that the PCU-2 is just a box with seven switches wired to a terminal block. Personally, I would not pay £43 for seven switches in a box. The PCU-2 is designed for use with a PCU-1, which includes a capacitor-discharge unit (CDU). Without a PCU-1, I think you would also need to buy a separate CDU - if you fed the PCU-2 directly from a transformer without a CDU then you might burn out all your point solenoids, depending on what type of switches are on the PCU-2.

The PCU-2 seems to be just an expensive way of buying seven switches wired into a box. There are much cheaper alternatives:

1) probe-and-stud. As explained by SCH117X, this is the simplest and cheapest, and the quickest to get you up-and-running. You can always upgrade to one of the other options later-on. Draw a sketch of your track layout onto a piece of paper or card, and stick it onto a piece of hardboard or ply. For each point, stick two studs into the plan, one to throw the point left and one for right. Solder a wire to each stud, and run it to the appropriate left or right terminal on the solenoid. You then just dab the probe onto the relevant stud and the point will throw that way. PECO make suitable studs and probes, but you can also use brass-headed drawing-pins or screws.

2) push-buttons: you would need two push-buttons for each point, one to control the point left and the other to control it right

3) switches: one two-way switch per point. Throw the switch one way, and the points move left, throw the switch the other way and the points move right. These should be momentary or passing contact switches, so that the power doesn't remain permanently on. You can mount the switches geographically on a layout plan, so that the position of each switch matches the direction its points are set. Or you can mount the switches in a row, like a lever-frame.

4) lever-frame: Triang used to make switches that looked like a lever-frame. You can buy these second-hand for about £2 each - searching for "triang lever" finds loads on ebay. So you could get 7 for £14, as opposed to the £43 for 7 switches in a new PCU-2. Different colour lever-switches are used for different functions - you would need the black passing-contact switches (R44) for point operation, not the yellow or green levers. If the idea of mounting and wiring up your own push-buttons or switches on a panel seems a bit daunting, then this is the option that I would go for. Simply clip as many levers together as necessary, run one wire from the CDU output to the lever-common, and then two wires from each lever to its associated solenoid.

The following page on the Gaugemaster site explains the various options in more detail:
http://www.gaugemaster.com/articles/guides/point-motors-solenoid-basics.html

With all the above methods, and the PCU-2, you would need to run two wires from each solenoid to the control panel. So you could change from one method to another later on. Again, with all these methods, the return terminals of all the solenoids should all be fed back to the negative output from the CDU. You can run individual return wires back from each solenoid. However, the simplest is to connect them all together on a terminal or bus-bar under the layout, and then just run one wire back from that to the CDU.

If you have two points that can always be operated together, such as a crossover, then you can simply wire the second solenoid to the first solenoid (A to A, B to B, C to C), so that both solenoids operate together from the same control.

Thanks very, very much. For some reason the idea of having the layout diagram with switches in didn't cross my mind, despite seeing it a lot on other layouts! I think I'm going to go with your option 4. It's the option which looks easiest for me and it removes a lot of the wiring which did seem a bit daunting to begin with! There are loads of signal levers on eBay which are on there for relatively cheap and I can see the appeal of having easy-to-wire levers which can be formed into signalling frames. I like the idea of having my own little "signalbox" (if you could call a row of levers on a baseboard a signalbox) on the layout, and it also provides the option of easily expanding the signalling system if I ever need to, which I may need to in the future.

Sorry for such a late response. I appreciate the effort everyone on here is going to just to help me with my little model railway - it's places like this which make the Internet so brilliant. Just people discussing model railways and the best way of making them work.

Thanks,

-Peter